Storm News Blog Archive

430PM, Thurs, 01/20: More problems....and wondering if "bait and switch" will be the motto this year

for our weather models in the DC area. The storm track continues to adjust north today, which takes us

into the warmer sector and reduces our already reduced estimations for snowfall....a recurring theme

this year. For everyone who has to drive through it....a good thing....but shooting forecasting skill

numbers in the foot. Because of this northern track adjustment...any chance of snow is on the backside

as it passes during the early morning hours and doesn't become a factor for tonight. So...only during the

early morning hours do we have a chance to see a few flacks....and a dusting may be optimistic.







630AM, Thurs, 01/20: The track of tonight's system takes the surface low through our vicinity, which

introduces temperature and precipitation challenges. For the most part this won't change our forecast,

although we'll lower the higher end of the banc and go with 1-2 inches as the general rule across our

area. Snow starts just a little later than first thought...likely closer to 10pm, and finishes tomorrow

morning by 7am. Late this afternoon/early evening we'll start providing updates on it arrival...it's

coming along as expected with little surprise (so far).







800PM, Weds, 01/19: Models are coming down today again which takes us back to where we were

about 36 hours ago....1-3 inches. No changes to timing from previously mentioned. Snow should finish

right around 7am Friday. A quick hitter with no real "big" snow attached...however...it is ushering in

another shot of Arctic air and temps for the next few days after Friday will reflect it. Next Tuesday

event still a small event. No "biggies" on the near horizon.







630AM, Weds, 01/19: Overnight runs have adjusted down slightly for the Thursday night into Friday

system, but not by much. We're thinking 2-4 is a good compromise for the day. Snow moves in from

the southwest after 8pm (like below), becoming moderate after 1am, and tapering off towards

daybreak. Our friends to the north and east, like they have all season, get more as the system begins to

wind up as it passes us. NYC - Boston is in the crosshairs again. Not as big as the prior systems...but

nothing to sneeeze at either... 8-12 would be a good estimate at this time. With confidence increasing

and this Thursday system seems well behaved right now, we're back into the red status. The 1/25

system track has been adjusting to a warmer track the past 24 hours, and looks at this time to be more

of a minor system with small impact.







700PM, Tues, 01/18: Interesting tidbit tonight. Both US models, which can be interpreted to estimate

snow down to the tenth of an inch, are predicting the exact same number for Dulles Thursday night into

Friday morning.... 4.5 inches. Usually you will see them swing a little bit but they are synchronized

tonight.

Meanwhile rain is approaching from the west tonight...and we might run the risk of some of it being

freezing again...as temperatures presently are only 32.2 degrees F. So areas north and west might have

to watch it again tonight for some ice.







630PM, Tues, 01/18: We'll have to go back to orange mode as Thursday night is shaping up to be

another fast moving, but decent snow system. The amounts have generally increased in our model

runs, with ranges from 3-6 inches in the models. This will be another overnight system leaving us a

mess for the Friday morning time period. I don't expect the snow to start until after 8pm Thursday

night. A better write up in a few hours.







0600AM, Tues, 01/18: Except for the northeastern sections the event is over and its time to figure out

how to get out of this mess. 0.22" of snow/ice at Stormy's location, which makes it just under ice storm

criteria...but amounts to the east will be higher. Roads are icy and nasty this morning, so take it easy on

the commute. We'll go into detail this evening on our Friday system.







1100PM, Mon, 01/17: Could be tough commute tomorrow....Freezing rain/sleet overnight and

snow/freezing rain north and west. No real changes or updates tonight...but after this passes (I'll

update in morning we'll also have to watch the Friday system.









830PM, Mon, 01/17: Heavier precipitation now entering our area. Sleet/Freezing rain in the District

and points south and east. Still snow north and west. Changeover to sleet/freezing rain occuring faster

than the models predicted, but as we've been hinting past few hours. If driving tonight...be

careful...road conditions are heading south quickly.







800PM, Mon, 01/17: Seeing more signs we'll have to become concerned with an ice event

tonight...model totals are crossing the 0.25 inch threshold and forecasters at the storm prediction

center are advising the DC area could see continuous freezing rain tonight. Keep your eyes on the

warnings for potential upgrades tonight. If this pans out the commute will become much more difficult

and would expect more school issues.







730PM, Mon, 01/17: A few stray flurries right at 7PM in Ashburn, plenty of virga overhead (meaning it's

precipitating aloft, but melting before hitting ground). Radar is filling in very fast now and

snow/sleet/freezing rain is just around the corner. I've added a few stations to the front page so you

can see the temperature contrast in our area (and Norfolk). We'll likely stay below freezing for at least

six hours, before attempting to rise. Model estimates of ice precipitation continue to rise

tonight...approaching 0.15 to 0.20 inches....of which an ice storm warning would be created for a

forecast in the vicinity of 0.25 inch. It may take a little longer to melt this off in the morning...so pay

attention to the temperatures on the front page. By 9pm we should see steady precipitation across our

area in many different forms. Sleet already in Fredericksburg and Manassas, snow at Reagan.







530PM, Mon, 01/17: A little slower moving in...rain as far north as Richmond at 5pm. Some late model

indications that warm air aloft is moving in faster, which would reduce the amount of snow and increase

the amount of sleet/freezing rain. Something we'll have to watch tonight as potential ice totals start

creeping up to the 0.25 inch range...which would like make NWS consider raising the ante with a

warning regarding the ice. A little early for that, but we've got a few hours before it gets here...now

looking at 7-8 pm.







300PM, Mon, 01/17: Rain is moving into eastern NC and extreme southeastern VA at this time, and

cloud ceiling heights are falling across the state of VA. Showers will begin to develop across eastern VA

over the next hour or so and move to the North. The rain/snow line will be roughly 60 miles south of

the DC area to start. As you can now see with the charts to the right, NWS has increased values

slightly....Stormy will still be calling for amounts to approach an inch for the western areas later tonight.

Also note the probability chart for freezing precip has changed thresholds from .01 inch to .10 inch...and

the probabilities for the western areas for that amount are in the 60-80% range. Everything else is

coming along as forecast. 1000AM, Mon, 01/17: On course, on schedule...although the snow may

start closer to 6pm instead of 7pm. All other aspects of the forecast remain unchanged as the system is

developing right now in the Gulf and looks impressive (for a winter warm system). Should note that the

southern areas of the immediate DC complex will have only a brief period of snow before the

changeover commences before midnight....







0645AM, Mon, 01/17: Happy MLK day! We've added a few more probability charts to the right, which

are NWS forecasts for snow and ice amounts. Stormy believes the snow amounts are slightly

underdone, but the overall pattern is representative of the expected event later tonight.







We're sticking with the game plan that light snow moves into the area, from the south, starting around

7pm tonight and remaining snow until midnight. Snow amounts will be in the 0-1 inch range. Around

1am, snow will begin to change and evolve through a brief period of sleet, followed by a brief period of

freezing rain, before becoming rain by 4am. Sleet/Freezing rain accumulations will be less than 0.1

inch, with the possible exception of areas west and north, which could be around 0.1 inch...and will take

an hour or so longer to change over to rain. We'll then see overcast skies with light rain off and on

during the daylight hours Tuesday, tapering off in the evening, and then restarting early Wednesday

morning for another 8 hour period. No changeover back to frozen is anticipated....colder air will move

back in, but after the precipitation has left us. For the Tuesday morning commute, the changeover may

be early enough to prevent ice related delays, but we're only talking about a timing difference of a few

hours to make it a bigger mess....so stay tuned in here. We'll update throughout the day as new info

comes in.







Another system comes in Friday....it does not look significant at this time, but subject to change as the

pattern shows itself.







700PM, Sun, 01/16: We're sticking with the gameplan as briefed this morning....snow starting after

sundown Monday evening, eventually changing over to sleet, freezing rain, and then rain. Snowfall

accumulations will be up to 1.5 inches, but predominantly around an inch or less. Changeover should

start in the early morning hours, with up to 0.1 inch of frozen precip...enough to put a glaze on exposed

surfaces. Towards dawn the temperatures barely make it over freezing, and a cold rain, worth an

additional 0.25 inch will fall. Total precip should be in the vicinity of 0.4 to 0.5 inch. The system is

splitting up into several pieces...so we'll see some more activity (light) on Wednesday, and another shot

on Friday with the next system, which may bring significant weather once again to the Northeast.



930AM, Sun, 01/16: Good morning! We'll go to red because we're certain of a precipitation forecast

which will include some of the frozen stuff...yet the exact mix is still a matter of debate. And there are

timing differences as well. I've seen model output which starts the precipitation as early as the

afternoon on Monday, and other data supporting a start time after midnight Tuesday. Taking a

compromise at this point...I'm thinking we'll see some light precipitation move in sometime after 7pm

Monday night. This will start in the form of snow and should last into the 3-5am timeframe, when there

is enough warm air aloft to change this to more of an ice mixture. Freezing rain/Ice Pellets (sleet) would

occur for a few hours and then hopefully switch over to a plain cold rain. Estimates of the snowfall are

around 1-2 inches, with another tenth of an inch of sleet/freezing rain, followed by a quarter inch of

rain. Total precip values right now appear to be on the order of 2/3rds to 3/4th of an inch. What does

become clear at this point is the Tuesday return to work commute may be a bit of a challenge. New

runs are coming in as I type this...so I'll update a little more frequently now (however an afternoon Caps

game may get in the way).







Note the charts on the right...there is some potential yet based on track to turn this animal into a

significant ice event...so stay tuned. Stormy

900PM, Sat, 01/15: We will continute to have to watch a the Monday night/Tuesday system closely

over the next 24 hours, as we've seen several different "alternative endings" being written by our

favorite models. The predominant story continues to be some snow moving into the area late on

Monday, which eventually changes over to rain during the morning hours on Tuesday. Whatever snow

does fall is quickly melted away by the rains. The tricky part here becomes the termperatures during

the day on Tuesday. One model suggests that indeed, termperatures aloft will become warm enough to

change the snow over to the liguid form, but for the western counties it suggests termperature may not

break 32 degrees, which means it becomes freezing rain instead of a cold rain...and we get caught up in

an ice storm. Whether we get anything this time is not really in the question...precipitation will fall, but

the question of the timing of the track will dictate what type we get. Tuesday at this time has the

highest probability to be a rain day, but there is a small chance we see some ice, particularly west and

something to watch out for. The eastern sections of the DC complex at this point are only looking at a

brief snow changing to rain scenario.







Fri, 01/14: We have a system coming in Monday night which will bring snow changing over to rain into

our area. This weekend will be cold once again as a southern stream system moves through the desert

Southwest. As the system begins to swing up to the northeast on Monday it will bring a significant

amount of precipitation, which will overrun some cooler air left over from the weekend. As a result we

expect snow to start Monday evening which will last through the night and begin changing over to rain

towards daybreak on Tuesday. Several inches could fall before changing over and being washed away

during the day on Tuesday. This is a western storm track at this point and confidence is high we will

see this change over to a rain event. The question is how much time the system will snow during the

overnight period.







900PM, Tues, 01/11: Another couple of hours of snow and then we're done for this system, which will

have left us anywhere from 1-2.5 inches across the area...lower than we thought...although some came

down as freezing drizzle. We've taken the next system off the board, as it appears now to be primarily a

rain event, but we'll reevaluate over the next day or so.







Maybe it just won't be our year for even a moderate snow. Our models are overforecasting the

potential and taking us for a bit of a ride. We'll have to temper our expectations. Be safe tonight and

tomorrow. NYC, CT, and places NE will have another big night tonight and tomorrow.







500PM, Tues, 01/11: To make matters worse, be careful on the drive as some freezing drizzle is popping

up in our area...another surprise as this should have stayed to our south today.

400PM, Tues, 01/11: It looks like we're going to be in the unenviable position of watching another

major snow storm start right on our borders and move to the north. Despite our models which have

been saying most of the day "trust me", time is moving by and we're not seeing much in the way of

developement. Meanwhile, NYC is getting ready for XMAS storm 2, which will bring in excess of a foot

of snow to that region. Our models just seem to want to mess with the mets heads here in DC...there

are many of us shaking our head once again at this near miss.







We'll see some very light snow in our area later this afternoon into the early evening...but getting

amount to exceed an inch or so will be the exception rather than the rule. Baltimore will be an inch or

two ahead of us down in DC, but the main action will be late tonight towards the NYC area.







This is the third bust for the models...and Stormy as well...not a good year so far. We'll keep watching,

however.







0615AM, Tues, 01/11: I love it when a plan comes together. Overnight model runs have come in and

are agreeing with Stormy philosophy....and NWS snow values have come up to Stormy values. Latest

NWS total amount/timing posted at right. We may see these numbers change a little bit in either

direction, but the values given at 0730 (below) are looking pretty good. Due to work-related

constraints...I will only be able to update information via the StormBlog site during the daylight

hours...there will be no news updates until 5PM on this page. It is also possible Winter Storm Warnings

could be issued this morning for our eastern sections. Timing is still looking at a 1-3 start, but closer to

3. And...this will be a quick hitter....peak snow between 5 and 10 tonight...tapering off after midnight.







1000PM, Mon, 01/10: Last Call tonight. One US model in and coming in roughly in line with our

thinking (slightly lower, but we're a little more optimistic). New Winter Weather Advisories for entire

area starting 4PM tomorrow through Wednesday morning...details on warning page.







Snow continues to move to the north in southern Virginia...but at a snails pace. Despite the Advisory

starting at 4pm we're sticking with a 1-3pm start time, particularly for our southern areas.







800PM, Mon, 01/10: Light snow crossing into Virginia from North Carolina, especially west and

southwest of Roanoke. Will only slowly creep north overnight.

730PM, Mon, 01/10: While we wait for new model data tonight....let's talk numbers







Western areas (Loudoun/Frederick) 3 inches



District/Arlington 3-4 inches



Eastern Areas (Prince Charles/Montgomery) 4-5 inches



Baltimore 4-6 inches



Eastern Shore 2-4 inches (mixing with rain)



Philadephia 7-10 inches



New York City 10-14 inches



CT/RI 12-15 inches



Boston 12-16 inches







Start times DC 1-3 pm Tuesday, Baltimore 3-4pm, Philadelphia 7-9pm, NYC towards midnight







Tomorrow morning rush: No issues



Tomorrow evening rush: Issues (Leave it to your imagination)







Confidence in this forecast is moderate....there are still scenarios on the table which could raise these

numbers...it should be noted Stormy's numbers are 1 inch higher than NWS in the DC area.







500PM, Mon, 01/10: Stormy is rather surprised not to see any advisories in our local area...appears

NWS is sticking to a track forecast further out to sea. Our preferred model mix still gives us the 3-6 inch

forecast you see on the front page and we'll stay with that. Our surface low still resides in the Gulf of

Mexico, although it is throwing some moisture to the north, with some snow activity already into North

Carolina. This system will slowly approach our area during the day on Tuesday....with snow starting

around 2pm in the immediate District area and continue to work in from the South and West. Heavier

amounts will be to the east of the city, and hence the winter storm watches currently posted there.

The latest runs I'm looking at suggest 3-4 inches on the west side and 4-6 on the east. More charts

forthcoming as we settle in for an interesting night and day.







630AM, Mon, 01/10: Depending on where you live in the DC complex the gradient for this storm will

cause some differences in how much snow you receive. Locations to the west will have the lighter

amounts, while the eastern side will be larger. Across the DC area the 3-6 forecast still looks about

right...3 inches for Dulles/Frederick, 4 inches for DC proper, and 5 inches to the immediate east.

Winter Storm Watches have been posted for the eastern zones of our area and locations further north

and east. Local watches are posted in the warning section. Timing might be a little slower than

advertised yesterday....tomorrow's morning rush should be fine, but the return journey will begin to get

difficult.







Due to some work constraints...Stormy will not be able to update this page until roughly 5PM

today...but we'll stay on top of it. Any immediate updates will be loaded into the Stormblog site at your

left.







930PM, Sun 01/09: One model has gotten more aggressive this evening causing Stormy to raise the

snow band back to the 3-6 inch range. More in the morning.







800PM, Sun, 01/09: Still on course, and the timing hasn't changed from the 9AM update today. We're

closely following the path of the storm and watching the interactions, but we have seen nothing for our

area to change our forecast. Further to the NE, it appears they will be hit hard again, with up to a foot

possible in the New York City area and further NE into Boston. Their second big storm. Much like last

season for DC, NYC appears to be targeted by mother nature this year.



200PM, Sun, 01/09: Status quo. Nothing to change our mind after the morning model runs. There is a

divergence of opinion regarding the evolution of the system, but all models are putting DC in the 2-4

inch range, with less snow west. We have to watch the mixing problem, which could cut the snow

down in the east, but too early to change that forecast. Our southern system has entered the Gulf of

Mexico today and is looking healthier than forecast, which is what we'll watch. Another update tonight.







0900 AM, Sun, 01/09: We're taking estimates down a little bit as the story becomes clearer, and there

will be a gradient of snow in our area. Later this afternoon we'll take a crack at a projected snow map.

Our two systems, one cutting through the Ohio Valley late Monday and a weak coastal low off the

Carolinas on Monday will begin to move towards each other overnight Monday into Tuesday. As they

begin to interact, they will begin to generate more organized precipitation. For the DC area, this

interaction is just starting as they proceed on up to the NE, so a few inches are likely in our area, with

larger estimates as you move up to the NE.







From a timing perspective the action doesn't start until Tuesday morning, with the bulk occuring in the

afternoon into the early evening. 2-4 is a good general bet...1-3 west. 2-5 to the immediate NE towards

Baltimore.







1030PM, Sat, 01/08: Another refinement to the forecast for the evening, but a minor one as our

models are telling us the Mid-Atlantic will likely miss (again) the brunt of this system. It will have more

moisture to work with compared to the last system for our area, but the Philadephia -NYC - Central MA

looks to once again be in the prime position. Timing for our area takes most of Tuesday down. We'll

see light to occasional moderate snows, with some mixing possible in the eastern and southern outskirts

of town. The best time for snow will be from 1pm to 7pm Tuesday, but light snow will begin as early as

daybreak and last through the early evening. 3-5 inches looks like the best bet right now, but this is a

complex system which still could throw us a curve.200PM, Sat, 01/08: We've had quite a sequence of

stories from our favorite models today concerning the Tuesday system...so I elected to wait to see the

European model before attempting to explain what's going on (or what we think is going on).







Unfortunately we have another pattern which allows a number of different actors to partake in the

play...and the roles of each have an effect on the outcome. I had mentioned earlier this reminded me

of the early December system, which brought a couple of inches to the area....and most of the US

models are staying with that scenario. However, after having noted how the US models

underperformed on the system which clobbered NY just after Christmas, there is a good case to be

made these models will make the same mistake, which would change our solution. Normally we

wouldn't make a big shift in snowfall thinking just based on the biases, but it appears the European run

today is thinking the same thing we are...which brings the storm track closer to the coast. In many

respects this looks like a hybrid system with a solution somewhere inbetween the early and late

December systems, but the other changing factor this time is we have a stronger southern system at the

outset which is allowed to "drink" more from the Gulf and transport it in our direction.







If I went strictly by the output from the Euro model...we'd be looking at 5-9 inches of snow during the

day on Tuesday, and we would have high confidence it was snow instead of rain, with the exception of

the coastline, where some mixing would occur. The US models, however, are talking more in the 1-3

inch forecast range. Smashing all of the data together...I'm thinking somewhere in the middle with a

nod to the Euro edition...hence the 3-7 forecast. We'll refine it later tonight as we get a few more runs.

We have higher confidence in this forecast bringing SOME snow to the area...I don't believe we're

looking at an all or nothing story like the last system...and Stormy won't face the criminal charges of

crying wolf.







700AM, Sat, 01/08: A little Saturday morning surprise as a band of snow has developed in the western

suburbs and is moving to the east at a decent clip. There is enough snow within the band to add 1/4 to

1/2 inch as it passes through. Snow should last for roughly 30 minutes. This band is associated with

yesterday's system...the upper level energy is the main culprit.530PM, Fri, 01/07: Our clipper

performed as predicted...with a dusting in the area...a little more to our north. Game over.







The tuesday system model runs have also been unremarkable....consistently keeping 80% of the system

to our south...to the point it is beginning to remind me of the early December system which brought a

couple of inches to our area. I've lowered the potential band down a notch because of this consistency

as the ingredients for a big storm are having a tough time coming together. In the longer

term....another system is forecast the week thereafter...but right now nothing looks scary.







600PM, Thurs, 01/06: Our weak clipper approaches tonight and we don't see much reason to be

concerned with any type of significant snowfall. I suppose "significant" can be measured in a variety of

ways...the fact we may see a few flurries in the immediate DC area prior to the morning rush could

cause a few problems, but there just isn't much with this system. To our north, in the Frederick area

might see just a little more than a dusting, but all in all a ho-hum event.







Our eyes remain on the late Monday/Tuesday storm system, which has seen a number of model

solutions over the past 24 hours. Overnight the story was for decent snows, but as the day has

progressed we're looking at solutions which keep the bulk of the system to our south. There is enough

variance in the solutions to warn everyone we could still see substantial adjustments to track, and a

coastal is still a real possibility. We'll keep the 4-8 inch target right now (if forced to commit would be

on the low end of that range).







630PM, Weds, 01/05: There is a lot of talk about the snow on Friday out there in the streets...but

Stormy is having a hard time getting excited about the possibilities. Perhaps the fact we've cried wolf

one time is hurting the excitement factor, but this still looks like a clipper which spends most of its

energy wiping out on the western side of the Appalachians and brings some flurries to our area during

the morning hours on Friday. As of right now the best chance looks to be from 4am to 10 am Friday

morning, and a dusting is about as good as it gets.







Our Tuesday system is changing slightly...from an outright hit to another glancing blow. Total precip

values were adjusted to the 4-8 inch values from our wider 3-10 inch band I put up yesterday. We'll

definitely have to watch this system as we could have changes in track....but we're comfortable right

now with this forecast. 630PM, Tues, 01/04: Happy Holidays and hope you are off to a good start on the

New Year.







We've advertised on the front page about 2 systems since late December, and for the most part our

story for you is not significantly different.







We're expecting a weak Canadian clipper to come through our area on Friday, ushering in some pretty

cold temperatures for the upcoming weekend. This is after a weak southern system passes to our south

during the day on Thursday, which begins to set into place the colder air we're expecting. As the

southern system passes, we'll cool down a few degrees on Friday, as the clipper approaches our area.

Normally, with the expected strength of the clipper and its current forecast trajectory across our area,

the DC area will be lucky to see flurries during the day into the early evening. A dusting...at best...is

expected at this point...so just some minor flakes to worry about.







As you know, however, whenever we get a real shot of cold air, you have to worry about whether a

southern system will swing through and take advantage of the cold air to bring snow to the region. This

is the second system we've advertised...and as we're getting closer it's beginning to look a little stronger

and better. At this point, the US and Europe models are largely in agreement (but remember our last

supposed system had the same features). Stormy will start to pay a little more attention over the next

few days and if we stay the course we'll do a longer setup tomorrow night.4PM, Sun, 12/26: At least I've

seen a snowflake....







It's trying to work its way this way...but the western side of town may be too late. We are missing a

brutal storm to our northeast this afternoon...the storm is approaching a point maybe 100 miles east of

the mouth of the Chesapeake, and is heading almost due north. We expect to see it move a little west

of north and continue to intensify this afternoon, which would allow it to throw snow back our way.

Eastern shorelines are getting significant snows as we thought...but so far out here in Loudoun we've

gotten a dusting at best.

1PM, Sun, 12/26: The storm system is just now passing Cape Hatteras and moving slightly east of north,

while continuing to deepen. In our area...flurries for the most part as far north and west as Alexandria.

As the storm moves up the coast the snow area will expand slightly west and more to the north...the

Loudoun/Frederick areas may miss most of this snow, but we are still thinking some snow will actually

approach from the east and northeast as the storm winds up later this afternoon. Meanwhile,

Southeast Virginia has been getting hit hard...almost 10 inches now in the Norfolk area. And...up

north....blizzard warnings across NJ, NYC, and part of CT.







Stormy forecast values and the current low/high spread of the available models:







DC and immediate areas: 2-5 inches (model spread [MS] 2-10 inches)



Western counties: Loudoun, Frederick: 1-2 inches (MS: 1 -6 inches)



Eastern Counties: Annapolis: 5-8 inches (MS: 3-15 inches)



Baltimore: 3-6 inches (MS: 2-10 inches)



Philadelphia:8-12 inches (MS 2-12 inches)



New York: 18-26 inches (MS12-24 inches)



Boston: 16-22 inches (reduced because of mixing issues)



Richmond:8-12 inches (MS 3-11 inches)



Norfolk: 10-14 inches (MS 4-12 inches)







1100AM, Sun, 12/26: NWS has lowered Winter Storm Warnings for the immediate area and reduced

their snow forecast values. We're watching the storm....and may lower as well







0930AM, Sun, 12/26: Storm is rapidly intensifying...a little stronger than forecast...and a little west of

track. Richmond/Norfolk getting signifcant snows already with reports of up to 6 inches in Richmond

and 6 in the Norfolk area. Obviously need to upgrade total levels there.







Stormy forecast values and the current low/high spread of the available models:

DC and immediate areas: 3-7 inches (model spread [MS] 2-10 inches)



Western counties: Loudoun, Frederick: 1-3 inches (MS: 1 -6 inches)



Eastern Counties: Annapolis: 6-9 inches (MS: 3-15 inches)



Baltimore: 4-8 inches (MS: 2-10 inches)



Philadelphia:9-13 inches (MS 2-12 inches)



New York: 16-24 inches (MS12-24 inches)



Boston: 14-18 inches (reduced because of mixing issues)



Richmond:8-12 inches (MS 3-11 inches)



Norfolk: 10-14 inches (MS 4-12 inches)









0630AM, Sun, 12/26: Our storm tracks are lining up at this point and the solutions are a little east of our

tracks last night. DC will miss the brunt of this system, yet have some snow as the system passes to our

East during the afternoon hours. If for some reason this jogs left of track, which is becoming a low

possibility, we'll let you know. This affects again our thinking on the west side of the precipitation field.







Snow is falling this morning over Southeastern Virginia from Richmond down to Norfolk, with moderate

snow now at Norfolk. Conditions there will continue to deterorate as the morning progresses and the

low moves up the coast. The northern edge of the precipitation will only slowly move up the coast into

the DC area as it largely pivots counter clockwise given the forecast path of the low. DC should start to

see some snow activity towards 1pm moving in from the Southeast. By 4pm most of the immediate DC

area, including the western zones should be snowing. Peak intensity snow will be from 4pm to 9pm and

gradually taper off from west to east. Peak intensity in the DC area will rarely approach moderate

levels. Farther east and northeast is a different story, being close enough to the path of the storm to get

much stronger snows. This low is expected to stall tonight just east of New York City bringing a period of

12-18 hours of heavy snow and accumulations from northern NJ up to Boston of 2 feet.







If you are a big time snow lover...DC will miss it, but get a taste, while the coast to our NE will be

smacked with a significant storm. Looks like it may be their turn this year. More updates as the day

progresses.

Stormy forecast values and the current low/high spread of the available models:







DC and immediate areas: 3-7 inches (model spread [MS] 2-10 inches)



Western counties: Loudoun, Frederick: 1-3 inches (MS: 1 -6 inches)



Eastern Counties: Annapolis: 6-9 inches (MS: 3-15 inches)



Baltimore: 4-8 inches (MS: 2-10 inches)



Philadelphia:9-13 inches (MS 2-12 inches)



New York: 16-24 inches (MS12-24 inches)



Boston: 14-18 inches (reduced because of mixing issues)



Richmond:4-8 inches (MS 3-11 inches)



Norfolk: 6-10 inches (MS 4-12 inches)







0930PM, Sat, 12/25: We're still in nowcast mode. One US model in which reduces snow for our area,

but some of the short range tools disagree...so I'll stand pat with these answers for the night...call it

early, and resume early in the morning....as I'm still comfortable with the numbers for now. Stormy







800PM, Sat, 12/25: Snow continues to very slowly move to the north...but should stall from moving into

DC proper until the morning hours as the low pressure tracks along the coast line. We're waiting for the

latest model updates and feed good about the current projected amounts. This will be a major news

maker for its impact to the NYC/Boston corridor tomorrow night.







615PM, Sat, 12/25: Our storm progresses, but haven't seen anything new at this point to raise the

forecast values....in fact...will probably tighten up the gradient of the forecast...with the following.







Stormy forecast values and the current low/high spread of the available models:







DC and immediate areas: 4-8 inches (model spread [MS] 2-10 inches)

Western counties: Loudoun, Frederick: 2-4 inches (MS: 1 -6 inches)



Eastern Counties: Annapolis: 8-11 inches (MS: 3-15 inches)



Baltimore: 5-9 inches (MS: 2-10 inches)



Philadelphia:8-11 inches (MS 2-12 inches)



New York: 15-20 inches (MS12-24 inches)



Boston: 10-14 inches (reduced because of mixing issues)



Richmond:4-8 inches (MS 3-11 inches)



Norfolk: 5-9 inches (MS 4-12 inches)5PM, Sat, 12/25: Both US afternoon runs in and they continue to

converge. If I were taken them verbatim at this point I would have to reduce values in the District and

points west by an inch or so...but I'm staying here until later tonight with the 11AM forecast (with the

increase to NYC at 2PM). It will be a sharp cutoff on the western edge. Light snow has started in

Charlottesville and Ice Pellets reported in the Fredericksburg area.







4PM, Sat, 12/25: National Weather Service has issued Winter Storm Warnings and Winter Weather

Advisories for the immediate DC area. These are posted on the warning page. Their estimates are

close to ours at this point, but we still believe a case can be made to go a little higher and we will

continue to watch tonight.







330PM, Sat, 12/25: State of NJ and most of DE now under Winter Storm Warnings...expecting Blizzard

warnings in the New York City area after 430PM. The local DC office has not pulled the trigger yet. 1st

US model (which has been further east) shifted slightly west...a good sign. No changes to snow

forecasts yet. This may come in a little faster than we thought this morning...snow has started in the

Richmond area as well.







230PM, Sat, 12/25: Entire state of NC now under Winter Storm Warnings. Biggest threat is

northcentral areas of the state, but everyone will see snow (coastal areas will be limited...expect to

change to mix/rain)







2PM, Sat, 12/25: Snow from our system is sneaking up into southwestern Virginia now...it will slowly

move in the direction of DC. The only adjustments to make to the snow totals right now would be to

increase the values in the NYC area...12 to 16 inches. This will be a blizzard in that area tomorrow night.

Updates will continue through the day as more data comes in.

1PM, Sat, 12/25: Still tracking the system....no more medium range model data until 4pm. Signs the

system is stronger than forecast as of right now. Watching later this afternoon to see if it tracks further

north/west than forecast, which is where I'm leaning right now. Keep an eye out for updates. Stormy









1100AM. Sat, 12/25: Morning runs are in....and the models predicted snowfall areas are starting to line

up better...Updated Stormy/Model spreads given below.







Stormy forecast values and the current low/high spread of the available models:







DC and immediate areas: 5-9 inches (model spread [MS] 2-12 inches)



Western counties: Loudoun, Frederick: 3-5 inches (MS: 1 - 8 inches)



Eastern Counties: Annapolis: 9-12 inches (MS: 3-15 inches)



Baltimore: 6-10 inches (MS: 2-12 inches)



Philadelphia: 9-12 inches (MS 2-14 inches)



New York: 10-14 inches (MS 8-18 inches)



Boston: 6-10 inches (reduced because of mixing issues)



Richmond: 5-9 inches (MS 3-14 inches)



Norfolk: 7-10 inches (MS 4-14 inches)







We will see light snow on and off over the next 24 hours....we don't see the real storm until sunrise

tomorrow. Peak snow times for DC, as of now, are 9AM - 3PM tomorrow. This window gets later as you

move up the coast. All of the models are in agreement of a major storm to hit the NYC area. At this

point we're in "nowcast" mode...watching the storm (just south of New Orleans) on satellite and

observation nets to see if it is behaving as expected. As the behavior changes we'll be tweaking the

forecast track/amounts.

0900AM, Sat, 12/25: Winter Storm Watches are going up as confidence increases about the track and

strength of the upcoming system. The DC area watch is posed on the warning page...although there is

still some hedging about the snow totals. Our storm so far this morning is trending much closer to the

heavy track, and I've added a Harris product which converts amounts into snow. It will not agree with

the Stormy forecast through the day as I make "secret Stormy" tweaks to the forecast, but it gives you

an idea of the overall trends. And....some light snow has started out here in Ashburn.



0730AM, Sat, 12/25: Some snow showers beginning to spread over western/northern Virginia after

crossing the mountains to our west. This is the beginning of the very light snow we'll see in the area,

but not really associated yet with the storm we're watching.







0615AM, Sat, 12/25: First of all....Merry Christmas!







All of our models are now bringing a coastal storm up the coast tonght bringing significant snows to the

East Coast. There are differences in how the models develop the storm and the extent of the

precipitation shield on the western side, and those differences could be significant in terms of impact to

those on the western edge of the shield. For DC, Baltimore, and Philadelphia, those differences are

extreme. Stormy at this point will side with model 1 over 2 (much closer to 1), but we will have to watch

this today as the storm develops. With some additional coffee, I'll work to refine these numbers.

Winter Storm Watches are popping up for immediate areas (which shall be posted on warning page, but

not for entire multi-state areas)







Stormy forecast values and the current low/high spread of the available models:







DC and immediate areas: 6-10 inches (model spread [MS] 2-15 inches)



Western counties: Loudoun, Frederick: 4-6 inches (MS: 1 - 10 inches)



Eastern Counties: Annapolis: 10-13 inches (MS: 3-18 inches)



Baltimore: 6-10 inches (MS: 2-15 inches)



Philadelphia: 9-12 inches (MS 2-16 inches)



New York: 10-14 inches (MS 8-18 inches)



Boston: 6-10 inches (reduced because of mixing issues)



Richmond: 6-10 inches (MS 3-16 inches)

Norfolk: 9-12 inches (MS 6-18 inches)



1115PM, Fri, 12/24: Santa is bringing the white stuff. Second US model now is saying west. Makes one

wonder about the runs earlier today as they are consistent. Heavy snows to our north, east, and south.







So...hold your breath.....







DC and immediate areas: 8-12 inches



Western counties: Loudoun, Frederick: 6-9 inches



Eastern Counties: Annapolis: 10-13 inches



Baltimore: 8-12 inches



Philadelphia: 12-16 inches



New York: 14-18 inches



Boston: 6-10 inches (reduced because of mixing issues)



Richmond: 9-12 inches



Norfolk: 10-13 inches







Some light snow tomorrow afternoon...but very light. System moves in from the south, bringing snow

to NC and southeastern VA towards sundown Christmas Day. Snow begins in the DC area towards mid-

night Saturday night, Baltimore around 3am Sunday, Philadelphia/New York/Boston around 9am

Sunday, and gets progressively heavier during the day. Peak snow times Sunday morning south, Sunday

afternoon DC, Sunday night Philadelphia, early Monday morning New York/Boston930PM, Fri, 12/24:

First model run in with supposedly "clean" data, and track is even further west. Was very hard to see

any difference from the runs which were tossed today...even more of a threat. Odds of an upgrade for

snowfall amounts around 11 are going up. Biggest threat in our area is to the east along the shoreline,

but if trends continue we could see some decent snow in our area....not calling for that yet, but its

setting up that way. Another supporting run in over the next hour and then we'll make a call.







545PM, Fri, 12/24: This has been a very exasperating day. We had a major shift in the models this

morning...only to be informed some bad data went into the models and we couldn't trust the results.

We then had another set of runs, and the forecast track went even further west...and now we're told

the runs are still "suspect". The European model ran and told us "out to sea". So as of this minute,

Stormy will stay with the "we're missed" story, but we really need to keep an eye on our runs this

evening, which will be started with completely new information and some guarantee the bad data has

been purged from the system. I will see the first run at 930, second at 1115, and will post then. We

could once again be looking at a surprise...I hope not...but this will be a storm (or not) to be talked about

in the weather prediction circles for many years. Hang in there with me! Stormy







200PM, Fri, 12/24: We're throwing out the morning runs and waiting for the afternoon runs all of the

morning runs are suspect. We will also stand down once again. Time for the investigation to start!







1230PM, Fri, 12/24: Major gaffe in the models? Folks in the US facility which run the models have

discovered initialization errors within the models for the morning runs...which may have

"contaminated" the morning solutions. Someone could write a novel on this story...we may have to go

back to regular programming....stay tuned.







1130AM, Fri, 12/24: US model is changing its mind regarding the interaction of the northern and

southern streams we've been discussing. It now brings them together (partially) which affects the track

solution, which brings the track closer to the coast again. It will take a little while to update the

charts/predictions, but a quick look gives DC a few inches....eastern shores much much more.







1115AM, Fri, 12/24: Surprise on the horizon, major shift in US model....very close....eastern shores may

be in the crosshairs







1100AM, Fri, 12/24: HOLD ON........







1000AM, Fri, 12/24: So close, yet so far. Evidence this morning continues to build that we just missed

this storm, which will wait too late to develop like we had hope and consequently most of the action

goes out to sea. Our models do indicate, as said earlier this morning, we'll see some light snow starting

towards noon tomorrow Christmas day and last through the late afternoon...enough for a dusting to

isolated accumulations. It will (like last storm) bring snows to the eastern most portions of North

Carolina and clip the extreme southeastern portion of Virginia with accumulating snows...on the order

of 1-3 inches Christmas night. It then moves out to see and begins to intensify and recurve to the

north...far enough to sea to only keep flurries to our coastline to the east. Sunday afternoon the storm

approaches the New England area from the south, bringing snows from the New York City area on up

through Cape Cod. By 4pm Sunday snows become moderate in the CT, RI, and MA areas. Heavy snow

would take over for Cape Cod by 10pm Sunday night, and modeerate snows will move into ME.







Expected snowfalls:







DC and immediate areas: 0-2 inches



Richmond: 1-3 inches



Newport News: 2-4 inches



Outer Banks, NC: 3-6 inches



Philadelphia: 0-2 inches



New York City: 2-4 inches



Long Island/CT: 3-6 inches



Boston/Inland Maine: 4-7 inches



Cape Cod: 6-9 inches



Eastern Maine: 8-14 inches







I'll update forecast totals/and snow reports during the weekend. Thanks for playing.







0630AM, Fri, 12/24: Sorry for the delay...server issues this morning.....







Overnight runs are looking pretty similar, and the fact we're approaching the event (36-42 hours) out

doesn't leave much room for changes. The ingredients were there for something special...and still are,

but our models tell us not this time. There is a reasonable chance we'll see some very light snow in the

late afternoon on Christmas day, but nothing much other than to tell us we are in that time of season.

We'll keep updating...but changes unlikely. Happy Holidays! Stormy







1000PM, Thurs, 12/23: Try as we might the models aren't budging much. We're seeing hints of a

western shift but nothing (yet) which would change our minds. So...we'll call it early tonight and restart

tomorrow morning after the early morning runs are in. 630PM, Thurs, 12/23: Afternoon model runs in,

with the regional model changing little, and the main US model has decided to tease us a little bit, by

shifting its track westward a little bit, which could bring some snow to the shoreline of the coastal areas

to our east. Stormy isn't biting on it for now, but closely watching the progression of our little system

which moved onshore in California last night and currently sits in northern New Mexico. At the same

time the models changed their tracks to the east they started downplaying the strength and longevity of

this system, which so far is much stronger than the models had thought. If this was to stay together, it

could affect the track once again, and could be the reason our afternoon runs shifted a little to the west.

Right now we have to say we will see some snowflakes, but very little in accumulations except to the

east and north. Extreme Southeastern Virginia may also be under the gun...which we'll watch. Travel to

NYC and further north towards Boston is still at a much higher risk of seeing measurable snows.







215PM, Thurs, 12/23: The trend continues to move against us as all of the models, including Europe

have backed off and moved this system track far enough out to sea to reduce our forecast numbers to

very small amounts. This has been one amazing forecast experience...to go from the Euro forecast

yesterday to the one we're looking at today...the change in forecast impact is driving everyone crazy.







Major brawls breaking out on the weather blogs around the area. No one wants to go from a 18 inch

potential to near zero.







Still some time for change...upper New England still in the impact zone...but our area is rapidly being put

out of the picture. Climatology stated the biggest snow ever in the DC area was just over 10 inches...so

yesterdays Euro forecast would have busted that. Shows you the power of that tool....maybe 150 years

of record keeping is worth something. We'll go down to yellow for now, but we're still watching this.

The models have had trouble with this combination and despite the fact we're getting closer to the

timing of the event...a surprise is still not out of the question. Stormy sure as heck doesn't like to cry

wolf....1000AM, Thurs, 12/23: Our first US model run is in and has shifted even further east with the

track. I'll keep the snow map until I see the second US run and the European edition at 2pm. The

trends are not going our way at this point. Hoping this isn't a repeat of last weekend when all we saw

was the cold air on the back side of the system.







0615AM, Thurs, 12/23: In a note sure to disappoint many, the models last night began to finally

converge on a solution and track where the models could agree on. This converged track, while not

seeming to be major, is enough to significantly change our outlook for snow. The track has been

adjusted to the east, close to the US model estimate last night....perhaps a shift of 100 miles...but this

divides the amount of moisture in our area by a factor of 10. So....we have had to dramatically

downshift our predicted range and tell you the prognosis right now is for a nuisance snow in the

immediate DC area.







Further north and south will still see higher amounts...south meaning eastern North Carolina and

extreme southeastern Virginia, as the low pressure moves out to sea, and then from northern New

Jersey, NYC on up and through Boston, which still get heavy snow as this system recurves to the north.







Why the change? .... you might ask. Well...as mentioned yesterday the runs last night for the first time

had much better data from ground based systems to understand the strength of the system moving into

California, which brought significant rains. Until then we were dependent on satellites which indirectly

measured this system.... the updated better data clearly told the models a different story...it was not as

strong as originally thought, and that changed the energy balance needed to make an East Coast storm.







It's not totally over...we have more model runs and this mornings will be the second shot at data on our

storm. Some folks last night argued the data wasn't entirely accurate and that threw off the

models...but we're not going to go down that path. This morning will be the second run and important

to confirm or deny this shift east. So...we'll lower totals (dramatically) for now and see where the day

takes us.









1115PM, Weds, 12/22: Our storm has come ashore out west and we're seeing more data regarding it.

The US models made an attempt to start heading Euro's way, and they did come...about half way....close

enough to bring at least some light snow into the area on Christmas day, but not an outright major

storm like the European edition. That said...we haven't had an update on the European model...its due

to come in around 1:30am. Like last night...we're not ready to stay up and get it...so we'll take a look at

it first thing in the morning. Our snow spread...still very wide...will remain the same for the rest of the

night...and hopefully we have good news for you in the morning. If the European stll holds...and 72

hours out it usually is quite deadly with its accuracy...we'll then have to talk about a storm. Until

then.... are over the next few hours, but the trend is lower right now and I've adjusted front page

numbers.







530PM, Weds, 12/22: The US long range model has made another adjustment towards the Euro

solution and this adjustment, while not yet bringing it back into the DC area, does impact areas north

and south of our area. Extreme eastern and southeastern Virginia is brought into the snow area, as are

areas later on Monday southwest of Boston on up through the Cape. Many times we look for trends in

the models and the trends are heading the way you would want for a snow story. With this run I'll raise

probabilities but continue to keep the spread where its at. Another adjustment by the US model

tonight and I'll start raising the predicted range of snow totals. Still too early for a snow map....but I'm

thinking about it! Next scheduled update late tonight...unless something more dramatic changes. Our

system is making landfall on the SW California coast at this time.







4PM, Weds, 12/22: Our second crack at the US models has completed the regional run...the run which

was a little bit gloomy this morning. It has improved this afternoon...not completely in the Euro camp,

but a solution much closer to it. The US long range output is next...although Stormy won't give it a lot

of weight as the afternoon run tends to be on the edge of the envelope most days. I've increased

probabilities and raised the spread numbers on the front page. I would love to tighten that spread to a

more manageable number...and I know the models have been increasing today...but there are a few

models not as optimistic. The good thing here is the Pacific system moves onshore tonight...so we will

have a better handle on that system and get that data into the evening model runs. Your TV and

government mets are struggling with this model spread as well, although you should start hearing a little

bit more of "stay close to this situation". And thanks for feedback on this site. Keeping everything

consistent on every page is a challenge.







130PM, Weds, 12/22: I am pasting the results of the latest European model...they are staggering.

We're going to be quickly confronted with choosing an out to sea solution or a top 10 storm. You may

want to consider grabbing a few items from you local stores before word gets out on the "potential" for

this storm. At the very least we will have forced you to get some extra "stuff"...and maybe we'll save

you some time in long lines. There is no other word to use but blizzard is forecast by the latest run of

the European model.







More...

Noon, Weds, 12/22: It's getting closer to white knuckle time...and I have some interesting news. Our

US model is beginning to say "hey European....I'm starting to like your theories.." So just as I start

adjusting down the model flips on me and says "not so fast". It doesn't paint the snowmegedon picture

the European solution has....yet...and in fact it would still say there isn't much of anything coming for

our area. It does dramatically change the forecast for the northeast....and we still haven't seen the new

Europe forecast, out around 2:15. Stay tuned!







1000AM, Weds, 12/22: Next regional US model is in and it is shifting towards a south and east solution.

This is not good news for snow lovers. Another run of the long range US and Europe models0700AM,

Weds, 12/22: While this is definitely frustrating for meteorologists, the impact here in a split decision

lowers the lead time our community can warn folks about the potential here. Some of the models

overnight have shifted eastward with their tracks, so there is some concern the European model and the

US regional models are westward outliers.







The difference in the models all depends on how they handle two pieces of energy coming together.

Will they? When? Where? We have a piece of energy approaching the southern California coast this

morning and this is expected to move along the southern US through the next few days. At the same

time, another piece of energy comes down from Canada. The models which are forecasting a more

eastward track delay the timetable for these pieces of energy coming together....whereas the European

and US model suggest it's earlier, which allows for intensification and recurvature to the north sooner,

which is needed to bring snow to our area. I will point out the track of the southern energy was first

considered an outlier track by the European model, and that has now become the preferred

solution...so one point for the Euro model. Now the difference is the phase point location and timing,

and the item we'll watch all day today for more signals.







The fact the CA energy comes ashore this evening also gives us a better shot of convergence on a

solution. While the Euro model has been the rock of consistency, a shift east would dramatically

change the forecast from heavy snow to a few flurries.....the line is that sharp. More to follow as the

next runs come in during the late morning and early afternoon.







0615AM, Weds, 12/22: The short edition this morning is the European model has remained steadfast in

a solution which would bring heavy weather into our area late Saturday into Sunday. The lastest run of

the US regional model is coming up with a similar solution...even though it still can't see to the end of

the forecast period. The main US model is coming around to this general idea, but waits until too late

to bring the storm back to the north and consequently the storm goes out to sea. So we haven't gained

any real common ground, as our models are fairly evenly split on this solution. What you will see based

on this is more "it could be big, or nothing at all conversation coming from your local mets. Stormy is

still inclined to go with the decent snow scenario, because that is a story which has changed very little

over the past 3 to 4 days. 11:15PM, Tues, 12/21: US long range model is shifting more towards the

previous Euro run. Not completely...but definitely a shift in that direction. It still does not give us a

significant snowfall forecast. 2AM European run next...cross your fingers....next note at 6am.







10PM, Tues, 12/21: Our first US model is in....the regional model, which only goes out 84 hours into the

future, which in this case is Christmas morning. As I mentioned earlier today we would use this model

to help us sort out which of the main long range models were handling the situation better...either the

US model, which give us a little it of snow and shoves the system to the south of our area out to sea, or

the European edition, which brought the low up the coast, strengthened it considerably and dumped

snow. Well... this regional model is not being a good country player as it is defecting over to the

European solution for this run. Again...it doesn't go far enough out in time to see the actual system in

our area, but the trends in this run would tell me it is agreeing with the previous European story.

Hopefully the next European model doesn't significantly change its mind! (which will come in at 2

am...and no...I will wait until 6 to report back to you...we're not in that mode yet.







We have another run of the US long range model coming out at 11PM tonight and I'll type a sentence or

two to let you know how it goes. As a reader you should start considering the impact of a European

solution, which would be a classic noreaster. Very strong winds, heavy snow from central Virginia up

through DC and further to the NE along the coast with Philly, NYC, and beyond seeing miserable

weather. I am not calling for that range of weather at this time...but the possibilties are real. One trend

during the day is the christmas eve timing is pretty much out of the picture. This is becoming a mid to

late Christmas day/day after Chrismas (weekend) storm....should it proceed down that path. Early

preparation for a storm may not be a bad idea...but don't buy the snowblower yet. Back in an hour.







630PM, Tues, 12/21: The US model has held serve...again with an out to sea track similar to the track in

red you see on the graphic to the right. We're waiting at this point to see who blinks first...but we

won't see another European run until the early morning hours...so all we can do is watch the trends of

the US models in their runs tonight. Is it 2 inches or 18? I'll stick with this wide spread of values until

we see some movement. I'm leaning more towards the Euro just because it has outforecast the GFS so

far this season...but not the greatest of reasons right now. More later tonight.430PM, Tues, 12/21:

There has been an amusing cat fight among all of the meteorologists up and down the coast over the

recent Europe run. A lot of excitement about a "big one" coming, yet just a few hours earlier they were

in a state of depression over the US model forecast.

Our US regional models are still not in range to seeing this storm, but they are getting close. During the

next 24 hours they will begin to assist us in sorting out which of the larger models has a better handle on

the situation. We've just completed another regional model run...and if we do a little extrapolation it

appears to side more with the Europe edition rather than the US edition, but not completely in either

direction...a little bit of a compromise on both. Europe snowfall totals (this won't verify, but

interesting) gave us 18 inches. The European data is harder to obtain and see...so we can't post

updating screens on their products like we do the US editions below. Next US long range model

coming in around 5:30.







2PM, Tues, 12/21: The European model is in and the infamous "B" word is invoked. What a contrast of

solution as this model, now for 3 days straight...six runs...brings this storm up out of the Gulf, right along

the coastline and bombs it out to our SE. I won't use the "B" word (rhymes with "gizzard") in this short

update but we now have a radical set of opinions...the US model says very little, the European says this

area gets hammered. The European run is slower..and that is the primary reason it itensifies so

differently. If the European edition verified this would be much more of a Sunday event rather than a

Christmas Day event. So unfortunately the spread on the front page widens again. Another update

around 5pm.







Noon, Tues, 12/21: Our tug of war between the models continues this morning for our weekend

system. We wont see the new European model run until 2pm this afternoon, but previous runs have

been rock steady so far in bringing a storm up the coast. The US models, are having a difficult time

staying close to a steady state...in fact the variance in their solutions lead to serious changes in the snow

forecast. Our most recent run flopped from a north track to a south track, which would yield only some

light snow on Christmas morning, with a couple of inches. We're still not out of the woods yet on the

Pacific system coming on shore, which starts late tonight...so we will continue to see changes in the

forecast. A hybrid solution right now between the models would still bring a significant system into our

area...so by no means are we out of the woods. I have lowered totals on the front page...and likely will

adjust them again after I see the European run. We hope this doesn't become another slider to our

south...but that is usually the trend in a La Nina pattern. I will delay the snow total charts for later in

the day since I'm not seeing as much agrreement as I would have expected.



0630AM, Tues, 12/21: I know there are some who are waiting for the forecast to change, but I have to

ruin your plans so far as our models are continuing to converge on a East Coast storm system affecting

our area on Christmas Day. There are differences between the US and European models (still) and that

should continue to get better today and tomorrow, but they are in agreement on a coastal storm

moving from the Cape Hatteras area up and along the coastline bringing snow to major cities and

interior zones. The US models "bomb" out the surface low just south of Long Island, whereas the

European version is south of that, more towards Southern New Jersey. The European edition is a

heavier snow producer for our area, so you know the criteria for which model you wish to root for.

Precip totals for both models are still relatively low...the US model struggles to give us .50" of liquid,

while the European gives us .5 to .75" of liquid. Roughly 6-8 for US, 7-11 for Europe, but we believe

these numbers are still low considering this is still a 100 hour+ forecast and we would expect values to

start increasing over the next 3 days.







Early this afternoon Stormy will begin to prepare snowfall maps alongs with timing charts for your

review. We won't change totals yet but our confidence in this forecast grows. No where near 100%

since a minor variation could still clobber this forecast, and the Pacific low still hasn't moved onshore,

but increasing anyway.715PM, Mon, 12.20: Another addition of the US models are in and we're starting

to see a little better agreement on the weekend system...but keep in mind we're still outside the 100

hour forecast window. The latest US run actually went a little further to the north, exiting the coast

around Cape Hatteras, and then proceeding up the coastline. Actual predicted values for liquid water

was only .46", which would translate to roughly 6 inches. We believe, however, that those values, given

the suggested track, are likely low...hence our snow spread on the front page, which I've adjusted

slightly.







New York City to Boston is in the Bullseye so far...but a minor change in track could increase (or

decrease our expected values). The Bullseye zone could see up to 18 inches. Starting tomorrow,

Stormy's graphics capabilities willing, we'll start producing preliminary snow forecast charts for the area.

We'll also begin to discuss timing...which also has a wide spread. Bottom line...the probabilities of a

moderate snow event continue to increase today...and heavy snows could also occur. Local TV mets

are starting to talk about the system...a good sign. Next update in the morning, unless a radical change

occurs late tonight.







230PM, Mon, 12/20: One complete run of both the US and European models are in...their tracks are on

the graphic to the right. As you can see the US models have continued to trend south with their

respective tracks. Europe has also shifted south and east, but into a much more aggressive storm track

(in yellow) running from along the Gulf Coast to along the Carolina Coast and up into New England. This

is a heavy snow track and if it were to verify we would look at amounts in excess of 12-15 inches.







So we're still stuck with dueling models. The good news is the Pacific feature which energizes this is

visible in satellite imagery now moving south of Alaska. It will enter the "lower 48" Wednesday

morning....which by then means the models should have reached much better harmony. Stormy isn't

biting on either solution yet and keeping the snow potential gap wide for now. The probability of at

least a few inches is increasing...meaning we're technically in a red status, but given current forecast

spread we will stay here.

Note also we've added more systems behind this one as the pattern becomes very energetic, and there

are several systems we will have to watch as each has some interesting potential. Stormy







Noon, Mon, 12/20: Waiting for the European models to come out around 2pm and then a write up of

where we're at. Meanwhile this will become "System 1", because the clipper tomorrow appears it will

completely be taken out as it passes over the Appalachians.0600AM, Mon, 12/20 (Ghosts in the

Machine?):







This is a blog/commentary to help folks understand the challenges of weather forecasting, and the time

is right to discuss what has transpired over the last 24 hours with the weather forecast. Needless to say

these are the days (and the reasons) why some weather folks don't like to commit to a forecast.







As we build better and better forecast models, procure bigger and faster computational power, with the

goal of forecasting further into the future we find ourselves limited by the fact that much beyond 72

hours of forecasts will very likely contain (or require) information about current activities which are

going on in the Pacific. And we have it better than the folks on the west coast. Despite the

advancement in receiving near real time observations from aircraft and satellites, it just doesn't

compare to the older (balloon) techniques for measuring the atmosphere.







For our current forecast and outlook the past few days have been remarkable in the fact the long range

models, both US and European were in remarkable agreement and consistent with the evolution of a

Pacific feature, which promised to bring a winter weather event to the DC area on Christmas

Eve/Christmas Day. Run after run suggested a moderate to heavy snow event, and from a forecast point

of view this was taking candy from a baby.







In our career field we learn never to take Mother Nature for granted, and yesterday she started to

remind us as to who's in charge. One of our models in the afternoon (which has one of the lower overall

performance scores) decided to take a walk on the wild side and dramatically shift the track to the north

and west, giving us a picture of brief snow turning into a cold rain. Early signs of panic and depression

began to show in the faces of hundreds of meteorologists or weather enthusiasts across the

Northeastern US.

And as usual...our defense in those situations is to wait for another run to see if the forecast signal is

confirmed. So...we all watched the next run come in for the US models around 11 last night. And of

course, it changed it's mind once again. It instead drove the track to the south, almost missing the DC

area...but close enough to deliver 8 inches of snow. So now the models have gone bi-polar.







The point is these variations can be pointed back to the Pacific data which started out this morning's

story. A relatively easy pattern has decided to become a little more complex in the Gulf of Alaska and

further to the west into the Kamchatka Pennisula...and that complexity has caused a perturbation in the

force.







So at 2am we patiently waited for the next edition of the European model...which has the highest

performance rating...to see what it would tell us. And, we weren't dissappointed...with a storm track

basically up the middle, spliting the difference between the two previous US runs and walloping the East

Coast...although a little slower. The European run suggests 12-15 inches.







The item which gives us pause is this would be a record setter for a strong LaNina, which we are in.

LaNinas are typically warm and just don't allow setups like the ones the models are suggesting. LaNina

is not a hard fast rule....but its something which also has to be considered.







And finally another US run has just come in....south of the European run but slightly further north than

its previous edition...so an 8-10 inch estimate would be derived.







This ultimately is the reason for the wide spread at this point on the front page. We're far enough out

to have a relatively minor change today affect the weekend forecast significantly. This is also the

reason you see the TV mets dodging the question everyone wants the answer to. Our recommendation

now is to prepare for snow, likely moderate in duration and intensity. Our 5-14 inch forecast will

tighten (hopefully) through time. The graphic at right shows the last 3 major models runs by the US

computers. They may not seem like significant track differences, but they make significant changes to

the forecast.1130PM, Sun 12/19: A short one...models went colder and much further south...so they

are having difficulty resolving this now. We'll stand pat and wait for the morning.







0930PM, Sun, 12/19: Our afternoon run was likely as bad as it could get (meaning...least amount of

snow..2.1 inches). A lot of speculation in the weather circles as we wait for the evening run, which

should be in around 11pm...and I'll give you the run down on that before we close for the night.

545PM, Sun 12/19: Well, you just knew it was going along too easy. Our first wrinkle, courtesy of Santa

has popped it's head into the equation and is giving us something to think about. Each run has slightly

shifted the track north and west...and the afternoon run continued that trend to the point our area

begins to get into warmer air and consequently....rain. So...we will back down a little bit, but we also

know the European model is still running colder, and the afternoon run of the US models typically don't

perform as well as the early morning run. A long explanation for that which I'll spare you now....but

we'll just have to keep watching this. A storm is coming in...there is little doubt on that. 2PM, Sun,

12/19: Europe runs in and track laying on top of US editions. Probabilities heading up.



1PM, Sun, 12/19: 14.2 is the new number....



Noon, Sun 12/19: Another set of US runs in and we're sticking to the story. I don't have storm totals yet

for the new run but would expect a 12-15 inch forecast. I'll change it when I get the number. What is

unfolding is the increasing probability of a Christmas Eve/Christmas Day storm affecting the Mid-Atlantic

up into New England. The main snow belt runs from the DC area northeast cutting through north

central New Jersey, the New York City area, and further into Boston. New Jersey to Boston looks like

the heaviest zone. This run was incrementally warmer...cold enough for snow, but of the heavier

type...another factor limiting somewhat the accumulations, but heavy regardless. Ohio Valley and Mid

Atlantic airports likely impacted Christmas Eve with delays....Christmas day will be miserable to drive/fly

for the areas mentioned above. We're still 5 days out...so room for change, but the fact our models are

telling virtually the same story run after run right now increases confidence in the solution.



8AM, Sun, 12/19: Our coastal is passing us by, so we'll remove mention of that system, focus somewhat

on the Tuesday clipper which looks less impressive run after run, and pay much closer attention to the

system Dec 24th/25th. All of our long range model, including the European editions are in substantial

agreement on the evolution and track of this system. A very strong Pacific system will crash into the

west coast early this week and then move inland. It rides up and over a ridge of high pressure in the

Western US, which is locked into place. As it slides down the backside of this ridge, it begins to once

again develop from what originally looked like a clipper setup to a moderate to strong low pressure

system moving southeast from the Plains. It brings with it a large swath of moisture, which it utilizes to

maintain itself as it crosses the high pressure. It travels to our southwest where it then flattens its

trajectory...passing to our south into the Carolinas before recurving back up the coast. Almost a perfect

path.



Our US model, which we can get much more information out of, has had a number of conclusions for

snow in our area during the past 36 hours. Starting Friday night...and every six hours thereafter...the

conclusions of this model for snow (in inches at Dulles) has been: 8.4, 8.6, 24.4, 5.9, 15.0, and 23.0.

So..you can see a wide varience so far. Given the agreement in the models so far it is prudent to

consider this range of values and note the lowest estimate is 6 and the highest 24. Being conservative

so far Stormy is keeping his estimates on the low side of this band...6-12, but if the consistency of these

runs continues and we also see agreement from the regional models, which will begin to get a look at

this system Monday, we'll have to adjust the forecast (higher).







With respect to timing....it has been sliding to a later start time...Friday night and continuing through the

day on Saturday (Christmas Day). From a pure track point of view the models have our area in the

"sweet spot" for this storm...the Bullseye is over Northern Virginia and Maryland. Snowfall amount

would actually taper off either to the north or south.



Because this storm has the potential to be moderate (or greater) we'll go back to yellow today overall,

but assessing this as an orange event. We will need to watch this one...which could be "the" storm for

2010-11 winter, as we do anticipate a warmer January/February in response to a strengthening La Nina

pattern.



10PM, Sat 12/18: No significant changes tonight. Tuesday system looks a little weaker, and the models

all over the place for the Friday/Saturday system. The model which forecast 24 inches this morning

now say 6 inches tonight....model mayhem. And...our system over FL is beginning to once again take a

hard look at the Southern New England coastline...so pay attention there. Long

Island/Connecticut/RI/MA are looking like they could see some snows starting tomorrow night.4PM, Sat,

12/18: Our system to the south appears to be running a little left of forecast track, which could shift the

edge of the snowfall a little further north and west. Not enough to catch our area, but closer

nonetheless. It's really too late for a major shift left...but you never know! The European runs are in

and they are in agreement in principle on handing the 12/24-5 system, which begins to raise confidence

in our having a white Christmas Eve/Christmas day event. One model has lost its mind and is suggesting

a major snowfall in the vicinity of .....hold on....24 inches.....but no way Stormy is heading down that

path yet. I'm comfortable right now with the 6-12 spread for potential and I realize that is pretty

wide...but we're six days out. More following with a late update tonight.



Noon, Sat, 12/18: A Christmas Eve surprise? US model making Friday night system stronger, raising

totals to a 6-12 inch range. Way too far to make definitive calls, and we know these models cried

"Wolf" on this last system....so strap on the seat belts.



0930AM, Sat, 12/18: Good morning to all. Our weekend system is forming in the Gulf of Mexico, and

still expected to slide out to sea to our south. The closest any snowflakes will get to the DC area will be

the Newport area...anything north of that will not receive snow from this storm. One change to it's

track..it does appear it will stay out to sea...so the New England concerns mentioned earlier have been

reduced.



Our next two systems are still in the forecast...although their respective timing has shifted later

somewhat. The tuesday 12/21 clipper, which is the weaker of the two events, is now looking like an

afternoon/evening event, looking like a duster to an inch or snow in the area. The system behind that

is stronger, and also a little later. This system has the potential at this time to be a 4-8 inch snowfall,

starting Christmas Eve around sundown and continuing into Christmas morning.

From a pure travel mode point of view the northern stream will be the active stream for the 48 hours

before Christmas day. Minneapolis, Chicago, Detroit, and Cleveland airports look to have the greater

chance of winter weather affecting operations and potentially causing delays. The southern hubs look

fairly clean at ths time. Stormy11:00PM, Fri, 12/17: Not much has changed this evening....new runs

in...but the story remains the same. The extreme southeastern portion of Virginia will see a little snow

out of our storm to the south, but that is the extent of the impact. Our other clipper systems remain on

the schedule listed below.



2:30PM, Fri, 12/17: As you will note from the probability charts to the right our chances of seeing

anything Saturday night or Sunday continue to decrease, as track of our system is looking to keep it out

of our area. The next two systems behind this weekend edition look to be on track...the possibility of a

couple of inches Tuesday morning and another, slightly stronger system on Christmas Eve

afternoon/evening. With the diminishing probabilities, we'll head back down to green status, but we'll

also update later tonight.



830AM, Fri, 12/17: Our models..only 48 hours out have finally begun to converge on a solution, making

the "near miss" the operative phrase. All of the basic ingredients were in place for a good storm, but

they will not apparently get together until just to our south. To our east, along the coastline will see

some light snow, but the bulk of the system moves out to sea, recurves to the north, and moves into

Maine on Monday.



A weak clipper is forecast to follow this system late on the 21st, and now the models for the past few

runs see a Plaines system forming which will move into our area on Christmas eve. The setup for that

system is similar to the system which passed us yesterday....but this could be a little more vigorous.



600PM, Thurs, 12/16: The game is just about over for today...just a shade under 1.75 inches of snow

here. Now we wait for the weekend storm (or not). Our afternoon US runs were uneventful and didn't

shed any new light on our forecast problem. In part that is because the afternoon model cycle just

doesn't perform as well as the early morning, late night runs. So...we'll watch the next cycle tonight

and let you know if anything is diferent, but the story as of now is a near miss, with a little light snow.



One thing to point out, however, late this weekend the areas from Philadelphia up to Boston are looking

like they could take a hit...with the Bullseye south of Boston right now. If you have travel plans you may

want to keep a close eye on this and consider contingency plans.200 PM, Thurs, 12/16: Just measured

1.4 inches of snow with snowmelt of 0.13", giving a snow ratio of roughly 11 to 1, which is about

average. Snow is tapering off in intensity in the western counties and that will become the rule to the

east over the next few hours, although some flurries and very light snow will continue until roughly 6pm.



Our weekend storm models, including the European edition this morning are now telling us to watch

this system closely. I've mentioned below the fact we were waiting for a Pacific system to move

onshore, which it will early tomorrow morning. Well...apparently these models are beginning to see

this system a little better, and the fact it's stronger than first advertised is affecting how these models

predict the track of the system. The European model has completely flopped back to a coastal runner,

from the Cape Hatteras area early Sunday to Cape Cod Monday. The snow prediction belts, if this

verifies again begins to bring decent snowfall numbers into the DC area...particulary to the east.

Coastline anywhere from DC north to Boston is again in the crosshairs. Since the models are jumping

around at this late date we can't say we have the greatest confidence in any solution...yet...but our

probabilities of snow are increasing again. And if that isn't enough, another clipper is forecast behind

this system, on the 22nd to bring more snow. White Christmas is looking very likely. More later.

Stormy



Noon, Thurs, 12/16: Snow has overrun the area, arriving a little ahead of schedule (which means it will

leave a little ahead of schedule) There is little to change for the current system. Our weekend system

still has some mystery associated with it as the models have reversed course for the 4th time, and

brought the storm track a little closer to our area. Not enough to bring anything significant, but if the

trend continues we'll have to start getting serious about it. Based on the fact we're pretty much in the

current event, we'll shift the probability chart to the right to start covering the weekend system. You

will be able to see how it changes roughly every six hours.



0900 AM, Thurs, 12/16: Snow moving into western Prince William, Culpepper counties. Snow should

start in Manassas around 10am.







0730 AM, Thurs, 12/16: No significant changes to our commentary for either system this morning.

Snow began in Staunton and Charlottsville Virginia (to our immediate west southwest) at 7am this

morning and continues to move in our direction. Snowfall amounts are given in the graphics to the

right, but the general theme of 1-3 inches across the area is still a good representation.



We still believe we will miss the weekend storm, which will remain far enough south of us and go out to

sea, only to recurve back into New England on Monday and bring big snows. Should this scenario

change we'll update it. After this near miss, the models show a few more clippers as possibilities, one

on the 22nd/23rd, and another on the 26th.



11:00PM, Weds, 12/15: Despite the fact our (and Europe's) models are reducing the chances of being

impacted by the weekend system, we will hold our probabilities overnight at 10%. But so far that story

isn't changing.



Our snow event tomorrow is on course, and maybe an hour faster...so I'll now go for a start time of

noon running through 6pm for the timing. Amounts unchanged from what was given below.

Tomorrow morning we'll provide frequent updates on the progress of our snow. Any reports from any

reader would be greatly appreciated! Have a good night.5:30 PM, Weds 12/15: 2nd US model is in this

afternoon and it has "blinked". Much more in agreement with the Europe solution which makes this

storm a non-player for DC. Upper New England receives the bulk of the system after it moves out to

sea and recurves into Maine. We'll continue watching.



Our clipper tomorrow is on track and the information below is still relevant. Look for snow to start in

the DC area around 1pm tomorrow...lasting for roughly 6 hours. Snows are heavier as you go south

from DC, Winter Weather Advisories in our southern counties, Winter Storm Warnings down further

south towards Richmond.



Another update later tonight. St



4:15 PM, Weds 12/15: 2nd run of US model #1 is in and it hasn't changed. What is shaping up is a

battle of the models tonight/tomorrow. The US models believe a Pacific system which will move into

Southern California tomorrow morning will play a much more important role than the European models

believe. The difference in those beliefs dictate their final track solutions. This model takes the low just

off the coastline. Far enough at this point not to be a major storm for the DC area, but NY and Boston

will get it if this forecast verifies. US model #2 run 2 is due in around 6pm.2:00 PM, Weds 12/15: The

European models are in agreement there will NOT be a system this weekend. The runs today set up an

interesting contrast of solutions between the Europe solutions and the US/Canadian solutions.

Unfortunately, for the snow lovers, the European models have consistently outperformed the

US/Canadian models. So not looking good. One of the stories has to be exposed as a bad story, and in

the not too distant future.







11:30 AM Weds 12/15: Second US model run in...has made same adjustments as model one, moving

weekend track west and north...bringing light snow to DC area and hammering New York up through

Boston. Stormy believes at this point further adjustments west and north are likely, although we are

awaiting the European models results.



11:00 AM Weds 12/15: First morning model run in...with some changes. Our clipper tomorrow comes

in faster than mentioned below, perhaps as early as 1pm instead of 4pm. Same duration and coverage.

For the weekend storm...it adjusted the track slightly further to the north/west...so stay turned. The

main models will start providing data to us over the next 2 hours. More updates as day progresses. ST



Morning, Weds 12/15: We're continuing to monitor both systems, our clipper/slider for tomorrow, and

the weekend system, whose story is constantly evolving. As of this moment, the clipper tomorrow gives

the greatest chance of snowfall in the DC area, while the weekend system, if it can move the forecast

track back into our area, offers a much greater potential for moderate/heavy snow.



Here is the synopsis for tomorrow. A weak, fast moving clipper will approach our area from the west

southwest tomorrow. Our latest model runs suggest we'll have another cold night tonight with winds

diminishing from what we've had the past 48 hours. Temperatures by 7am tomorrow will be in the

upper teens west and north of DC, around 20 in DC, and low 20's south and east. Clouds will be rolling

in during the early morning hours, and snow, moving in from the southwest, is expected to reach the

district around 4pm. Since the bulk of this system will stay to our south, the gradient of snowfall will

also range from north to south. In the immediate DC area, north of the Potomac, we expect we will see

anywhere from a dusting to 1.5 inches of snow. Northern Virginia, DC, Prince George Counties, etc,

should see 1-2 inches. Further south, towards Fredericksburg will see 1.5 to 3 inches. The snowfall,

when it starts, will quickly become moderate in intensity, and with the cold soak temperatures we've

had the past 48 hours the snow will quickly begin to accumulate on hard surfaces and/or grass. Snowfall

rates should reach their peak between 6 and 7pm. As quick as it moves in it will also move out...by

10pm. So we're looking at a quick hitter, lasting no more than 6 hours. Of course...this will clobber the

afternoon rush home from work.



Our weekend storm is still giving us fits on predicting its path, because we are still dependent on

activities currently going on in the Eastern Pacific. Some of those features will not be well observed

until tomorrow, meaning the track still has some opportunities to change. Yesterday morning the track

was about as bad as it could get, indicating heavy snows from Central Virginia up and along the coast to

Boston. One foot snows for our area, with a 18-24 inch sweet spot northeast of Philadelphia and west

of New York. Since yesterday morning, however, the models have every six hours adjusted the track to

the south and not brought all of the major atmospheric players together. As of the 1am runs this

morning the track was far enough south that the DC area would not even see a snowflake (Maryland

shoreline would receive some). So a real turn of events. Our advice right now is to continue to monitor

(through this site of course!) the situation...it is still rather fluid and we could see some adjustments

back to the north and west. The chances this comes back at us are getting smaller...like 20% or so as of

now...but definitely still a possibility. In fact, we'll update around noon as we see the first results from

this morning model runs.



Evening, Tues 12/14: As the day has progressed the models are beginning to back down from the red

alert drill we were working on earlier today. Our Thursday system outlook waffles from a dusting to

maybe an inch...so we'll have to watch that. The weekend system, with the possible exception of 1 US

model, are now indicating the system will move out to sea with minimal impact. The message tonight is

there is still a wide range of scenarios and the present track forecast carries a low confidence figure.

We will continue to watch for the story for the weekend, and tomorrow morning we'll provide some

better detail on the timing/amount forecast for our smaller Thursday event.



Early Evening, Tues 12/14: Our second run this afternoon is confirming the early runs which bring a

storm along the East Coast late Saturday and through the day on Sunday. There are some differences,

which affect the amounts we're currently thinking for our area, and since we're still out some 108 hours,

the amounts/track can still significantly change. As for the Thursday slider, we're flip-flopping on

whether it brings anything serious to our area. As of right now...a dusting at best in the immediate

area, but also still subject to change. An early estimate for Saturday is snow moving in around 7pm and

continuing through the night. Estimates from the morning model runs were in the vicinity of a foot of

snow, but the afternoon run has come down somewhat into the 6-8 inch range. As we said earlier, a

moderate snow event is anticipated. This is not a setup for a superstorm, but the pieces are falling into

place for our first significant measurable storm. We'll update again late tonight after the next

runs...and we still plan on upgrading status tomorrow.



Noon, Tues 12/14: Major changes in the forecast today as our models have taken a turn for the worse.

We are waiting to see the European models come in this morning, but 2 US models now call for a

substantial East Coast Storm this weekend. And...one of those models says we will also have some snow

on Thursday...the one or the other scenario has been replaced with "you're getting it twice". Should

the story remain constant today, we'll go to orange mode tomorrow morning, meaning we'll also open

up the stormblog site for routine monitoring and discussion.



Morning, Tues 12/14: There is an interesting connection occuring between our two systems...the first

system may very well signal the intent of the second system, largely because both are affected by the

cold air in Canada in different ways. It appears we're in a mode of "you will get one or the other".

Overnight the models have shifted the track of the first system further to the south, with just the

northern edge of this "slider" grazing the extreme southern edge of the DC area. At the same time, the

models are shifting the weekend track to more of a coastal track, with the potential increasing for a

bigger system affecting our area. So...our probabilities go down for system 1, and increase for system

2. In the aggregate, we'll keep our status at yellow for the time being, because if the second system

were to verify we could be in for a moderate strength storm. More later around noon.



Morning, Mon 12/13: Things are beginning to pick up for our system on the 16th, as more models are

suggesting we'll see a minor, but measureable event on Thursday the 16th. Being less than 72 hours

out from the system, we would expect confidence to build, and so we're once again heading to a yellow

status. The story looks like this: Clouds will start rolling in overnight Wednesday and temperatures in

our area will get into the mid 20's. Towards daybreak Thursday snow will move into the area from the

west southwest. Snow will become moderate at times around 9am...but only lasting just afternoon

when the snow will quickly taper off, with isolated snow showers thereafter. Given the short duration

of the snow accumulations will be on the light side...Stormys best guess is 1-2 inches right now. What

may make this system interesting is how quickly it moves in, snows, and moves out. With regard to the

system on the 20th...the models are still digesting and thinking about it. There is the potential for a

significant system with this setup...whether this is an East coast storm or merely a system which quickly

goes out to sea are two distinct possibilities, so confidence remains low at this time.



Evening, Sun 12/12: A slow day at Stormy's hideout, watching the rainfall and wondering whether

there will be any white stuff on the back end of this system. Since we don't think we'll see much...it's

time to start talking about our Thursday system, which in some weather circles is already being

described as a "Southern slider". What's happening here is the next set of Pacific energy moves across

the US during the early part of the week and runs into the cold air left behind by the system moving in

tonight into our area. The cold air will deflect this energy to some extent, but in the act of deflection it

will also squeeze some moisture out of the energy and, in the cold air, make this into an overrunning

snow machine. The last few model runs had suggested this area would stay to our south, and some

models continue that story, but at the same time we're now seeing other models begin to shift the

deflection point further to the north, with some precipitation into our area. As always...we'll watch this

over the next few days. Our other storm is still in the conjecture stage...we'll comment more

tomorrow.



Morning, Sun 12/12: If you look at the temperatures on the real time observations from the front page

you will see quite a contrast in temperatures across our area...from the upper 30's west to the lower

50's east. Everything going to plan this morning with the front moving through somewhere after

sundown this evening. Our chances of seeing any white stuff is fairly small...again, just a flake or two

and then the moisture moves out and the cold air comes in. The system we're watching for the 16th

right now is looking like it will skirt to our south, but we'll continue to monitor, while system #3 is losing

some potential, but still early in the game and it may slide back a day or so. White Christmas?



Evening, Sat 12/11: We're primarily watching the back end of our weather system, which promises to

bring rain to our area in the next few hours. In the higher elevations of WV to our west and Northwest,

its possible, as mentioned this morning, it may start as an icy mix. NWS (see warning page) has issued a

Winter Weather Advisory for those areas overnight. On the back end, we see the possibility, primarily

in the areas west and north of DC, of seeing roughly an inch of snow as the system moves out Sunday

night into Monday morning, and the much colder air begins to move in. Since we're only talking an

inch...we're not changing our alert status...but we'll continue to watch this over the next 24 hours.



Morning, Sat 12/11: Not going to change much today as we await the system. There is one minor

wrinkle, and I thank Kevin Johnston for pointing it out. It's possble later tonight as the precipitation

begins to move into the area we'll see a little mix of frozen precip with the rain. Changeover to rain

should be relatively quick, but we may see a flake or two, or a "ping" on the window when it starts. In

addition, we'll watch the back end of this system. As mentioned before we expect a changeover back to

snow for as little as an hour or so when the cold front moves through tomorrow night.



We will also start commenting on the next system in the barrel, Thursday, which is caused by the

approach of a minor impulse on the day...it appears it may be stronger enough to generate some

precipitation and the cold air from this weekend's system will still be around. Also, the long range

European model suggests another coastal system is possible on or around the 20th.



Late Afternoon Fri 12/10: No changes today...except we were a little surprised to see the clipper which

was expected to remain north of our area today actually bring a band of very light snow to our area in

the late morning. The weekend storm is progressing as advertised yesterday, with blizzard warnings

now posted for the plains states. Our setup just never came together for a significant white storm

here...we'll stay on the warm side of this system for most of the time.



Rain will move into our area from the south after 10pm Saturday night, occasionally becoming moderate

at times during the day on Sunday. The real front will move through the area towards sundown Sunday

night, with the rain tapering off and likely changing over to some snow flakes for an hour or so with no

real significant accumulations. Temperatures will plummet Sunday night with frigid Arctic air quickly

moving in behind this front. Monday looks cold and blustery again, lasting into Tuesday with the

coldest temps we've seen so far this Fall.



Late Afternoon Thurs 12/9: Another set of runs and the answer is coming out the same. The preferred

storm track keeps us in the warm sector for 98% of the show...for which we might see a few flakes on

the back end of the front as it goes through us Sunday night. Although this pattern had some serious

potential, it is looking more and more like we'll miss this one. But we will still have to pay the bill for

this terrible meal we're about to be served. Frigid temps will move in on Monday with gusty winds

lasting through the day on Tuesday. Will chills will be lower than those experienced this week. Based

on the latest information, we'll step the probabilities back down, with an expectation the commentary

tonight/tomorrow will put us back into a green status. Oh well.



Early morning Thurs 12/9: We're starting to see the models come together on a picture for the

weekend..I still think there is room for change in this story, but I'll begin to lay it out and give a much

better description this afternoon.



This has turned out to be a rather complicated forecast, because there are several different players in

the game. The end result won't be dramatic based on our current understanding of how the actors will

play, and there is still room for them to change their roles. Actor 1 is a clipper moving across the

northern boundary of the US today, tomorrow, and Saturday. This clipper is acting as a gate for the

Arctic air up in Canada to funnel through on its way south. Depending on its location, this gate either

assists or blocks the air from coming on down. Actor 2, the lead role, is the remnants of a Pacific low

which is forecast to fall apart during the day today. The energy associated with this low begins looking

for a new home as it moves onshore the Northwest coast of the US tonight. It rapidly moves to the east

and southeast and during the day tomorrow begins to mingle with the Canadian air. This is where the

dance gets interesting. The faster these two actors get together, the faster they combine into a potent

surface system. If this happens too early, the storm generates and starts moving north, which means it

ultimately tracks to our west, which keeps DC on the warm side, ergo rain. What we believe is going to

happen is the two actors are going to come together, but only after some time has passed. The

courtship may take longer than normal, which allows this couple to move further east. By the time they

really are interested in joining forces, Actor 3, a weak surface feature along the Carolina Coast becomes

of interest to the primary actor. The attraction to Actor 3 becomes strong, and ultimately becomes the

dominant low. The effect here is the low then track to our east...close enough to give us some

precipitation which quickly turns into snow. This is not setting up for a major storm for our area...more

of a nusiance snow at this point....less than 4 inches across the area as of right now. Later today we'll

do our first crack at timing and amounts for our area, and we'll also watch a few more updates on the

models. ST



Evening #2 Wed 12/8: More model runs coming in tonight and we're shifting back to a west/rain track

for the evening. The spread remains high (as expected) in the range of solutions for the storm track,

since we're still hostage to most of the system still being offshore in the Pacific. I expect these models

to change their tune for the next 24 hours. No changes in probabilities....right now...if pressed....it looks

like a rain event with really cold air on the back side of the system. More tomorrow morning. ST



Evening Wed 12/8: Considerable confusion today as the models starting walking the track further east

with one model (although of low skill) absolutely clobbering the east coast (DC) with snow. I still

consider this to be an outlier solution at this point, with the better answer we'll see rain during the day

Sunday (a real cold rain) changing over to snow for a brief period early Monday morning. The potential

for this to be a bigger snowstorm remains a reasonable probability, so don't go away just yet. We are

still waiting for one of the key factors to show themselves...I don't think that will happen until tomorrow

night (Thurs). Nonetheless, from an interest point of view I will raise the probablities slight on the front

page, but keep us in the yellow area for now. Remember if we go "orange" we'll start exploiting the

stormblog capabilities. We'll put out a note later tonight.



Note: If you look at the chart on the lower right of this page you can see there is considerable spread on

forecasting the storm track. The "experts" are going north, meaning warm and rain, but I'm not sold on

that just yet. ST



Evening Tues 12/7: We're upgrading to yellow tonight as the models continue to throw wrinkles at us.

Today's European run is convinced the upcoming storm will move into the Great Lakes, bringing a rain

even to the DC area followed by bitterly cold air. Meanwhile the US models have vacilated today, the

early runs being in agreement with the European solution, yet this afternoon the latest run goes back to

a coastal low scenario. I've mentioned several times the connection to the Pacific system, which won't

be resolved for a few more days. So we will continue to see the models wiggle the track. In the

aggregate, however, we have to say the probabilities for some snow has gone up, but we're still talking

about small amounts at this time. Confidence remains low for the forecast track, while confidence is

high on the cold air outbreak behind this system, which will bring air to our area direct from the North

Pole. You get the picture.



Morning Tues 12/7: Overnight the models (with the exception of the Europeans) have trended the

forecast track of the next system further to the east...close enough for us to again consider the

possilblity of some frozen precip on the back end of the system Sunday/Monday. We're still waiting

(and going to be waiting until Thursday) for one of the key pieces of the forecast to become more visible

to the models, and that is the Pacific low now in the Gulf of Alaska, which the models have shown to

have different scenarios into the future. If the storm track remains where it currently sits or starts

moving further east, we'll upgrade to yellow by this evening. The models are in absolute agreement

that there will be a significant storm in the eastern US, and that the cold air behind this next system will

make you think the current bout of cooler temps was warm.







Evening Mon 12/6: Most of the meteorologists on the East Coast are jumping off the bridges

tonight...what once appears to be a major storm now appears to be bringing a cold hard rain, followed

by another shot of even colder air than we've had early this week for a decent portion of next week.

The track of this system is waving all over the place, so Stormy isn't ready to say nothing is going to

happen yet and we'll continue to watch. Since the current concensus view is rain, we'll stay green on

the watch code for now.



Morning Mon 12/6: A short note....Sunday/Monday next week still one to watch - overnight runs have

warmed the scenario up to more of a cold rain picture as the storm track currently takes most of the

promised system to our west, but still plenty of time to watch this story evolve. More later today.

Evening Sun 12/5: The weather geeks have been getting a little more excited over the "possibilities" for

the system next weekend, although the models so far are telling us virtually anything is possible. With

some confidence we're looking at a decent system developing in the eastern half of the nation, but the

track runs as far west as the Great Lakes to another system going out to sea before significantly

developing. So....we'll watch and report. Meanwhile, chilly, cold, and blustery the next few days.







Morning Sun 12/5: Ok, enough whining about missing the snow to our south. After attending last

nights depressing Caps game I put this miss into perspective. That said, there are more opportunities to

talk about as Mother Nature is moving into winter mode and generating an active pattern towards the

end of this week. We've been dealing with a blocking pattern the past week in the Northern Atlantic

which hasn't allowed the kinds of energy needed for winter systems to move and propigate through the

U.S. It appears this will start changing this week as a number of clippers will interact with this block and

finally move it out of the way. Clipper 1 is a northern stream system, which will skirt to our north on

this upcoming Friday, and once again we won't see much weather out of it, other than some reinforcing

cold air, which will pile onto the iceblock we'll be under during most of this workweek. Clipper 2 is

looking more interesting, arriving on Sunday, the 12th. Some of our tools want to evolve this into a

subtantial system, with the potential for an east coast system. Early looks at the rain snow line for a

system like this keeps the line just to our south...meaning snow. 7 days out...very early...however the

upgraded models performed exceptionally well for the clipper which went by yesterday, so Stormy will

consider what they're advertising this far out. At least it gives us something to talk about. Now...we

just need to deal with the "it happens on the weekend" problem. But that's for another discussion.

Quiet for today through Wednesday at the very least with cold, dry, northwest winds. Bundle up!







Early Afternoon Sat 12/4: So close....snow cutting across the mountains as far north as Hot Springs, with

moderate to heavy snowfall occuring along the VA/NC border (western half) as of 2pm. Have added a

24 hour observed snowfall chart below this discussion. No changes to the comments from this

morning...a flake or two may be seen in our area, but the action was to the south for this system. The

12/12-14 system is beginning to look like the potential for another clipper system...similiar to the one go

by today/tonight.



Morning Sat 12/4: Our clipper this morning is on track and about as predicted....the models continue to

score well. The extent of the precipitation as of 8am covers southern Wisconsin, northern Illinois, most

of Indiana, central Kentucky, eastern Tennessee, and extreme southwestern Virginia. The northern

edge is just a little further north than modeled yesterday, which gives the DC area and particularly areas

south of DC the chance to see a few (but non accumulating in the DC area) flakes. South of

Fredericksburg the chances start improving, with the potential of a dusting up to an inch or so as one

moves closer to the border.



Evening Fri 12/3: The models have performed well on this system, with consistent answers 96 hours

out and little changes from the forecast. In real time the snow is falling across the eastern Dakotas,

southern Minnesota, and is moving into northern Illinois. This belt of snow will continue to dive to the

southeast, reaching southwestern Virginia early tomorrow. In the higher elevations 4 or more inches

are likely, with much lighter amounts to the east and southeast from there tomorrow. As the impulse

passes to the south of DC overnight Saturday the winds will begin to pick up and the dewpoints will

drop, signaling the next phase of the system, which calls for rapid intensification offshore, bringing cold

northerly winds in our area on Sunday. The upper level system supporting this will park over the

Northeast the next few days....heavy snows will hit northern Maine on Sunday and Monday, probably

news worthy amounts. For us in the DC area....just cold and windy.



Early Morning Fri 12/3: No changes this morning to the commentary on the Saturday night/early

Sunday weather. Snow passes to our south, and we see the winds/colder air push in behind it on the

day Sunday, which will become rather blustery and cold as the day progresses. Longer term we're

seeing hints of a east coast system in the 12/12 - 12/14 timeframe...but this far out all we can do is

comment there "might" be something out there. Otherwise, for the weatherman...a boring week

shaping up next week with little weather and cold temperatures.







Evening Thurs 12/2: We'll lower probabilities to just above zero as the models remain steadfast tonight

that the clipper system will pass to the south, with the highest amounts of snow in our vicinity in

extreme southwestern Virginia and to a lesser extent along the NC/VA border as it moves out to sea

overnight Saturday. Once this system passes we'll have, as mentioned this morning, some pretty cold

air parked over our heads for the first half of next week. Towards the latter half of the week we'll be

watching the next potential system. Have a good night! ST







Afternoon Thurs 12/2: Another round of model runs are in and the situation remains static. The

chances of the clipper affecting the DC area are going down, although the southeastern Virginia area is

still looking like it could be affected. As such, we're going back to "green" status for the time being.

Graphics from some of the models we're looking at will continue to be posted here despite the near

miss of this early season clipper.Stormy Log