Weather or Not?
Weather basics for sound decision
making!
What to do for bad decision making?
Resources for Weather
Good- Before!!
– Newspaper
– TV- Danny Treanor????
– VHF radio-Weather channels
– Computer- Internet-NOAA
Better- During Trip
– Smart Phone-Accu-weather
– Satellite weather on chart plotter-XM or Sirius
– Radar
– Read the sky?
BEST- ALL of the above!!!
Types of Clouds
Cirrus Uncinus
High Ice Clouds. Good Weather if winds from W, NW to N. Precipitation
likely within
20 to 30 hours if winds steady from NE, E to S
Types of Clouds
Altocumulus Translucidus
Water and ice clouds. Some precipitation likely within 15 to 20
hours if wind is steady NE to S Other winds bring overcast sky
Types of Clouds
Nimbostratus
Rain or snow clouds. Precipitation of long duration if winds NE to S,
or shorter duration if winds are SW W to N
CONVECTION
Lifting by Convergence
broad lifting of an entire layer of air
Convergence is an atmospheric condition that exists when
there is a horizontal net inflow of air into a region.
When air converges along the earth's surface,
it is forced to rise since it cannot go downward.
Cumulus Congestus
If clouds form from SW to NW, precipitation with
gusty winds and thunderstorms or wind squalls
are likely within 5 to 10 hours.
Stratocumulus at sunset
Low to middle water clouds with gold, pink, amber, lavender or rosy background.
No precipitation likely within 20 -24 hours
Stratocumulus at Sunset
Low water clouds of dark Indian red color.
Precipitation in 12 to 20 hours if winds from NE to S.
Other winds bring overcast sky.
Forecasting
Persistence Method
today equals tomorrow
There are several different methods that can be used to create a
forecast. The method a forecaster chooses depends upon the
experience of the forecaster, the amount of information available to the
forecaster, the level of difficulty that the forecast situation presents, and
the degree of accuracy or confidence needed in the forecast.
The first of these methods is the Persistence Method; the simplest way
of producing a forecast. The persistence method assumes that the
conditions at the time of the forecast will not change. For example, if it
is sunny and 87 degrees today, the persistence method predicts that it
will be sunny and 87 degrees tomorrow. If two inches of rain fell today,
the persistence method would predict two inches of rain for tomorrow.
Effects of Frontal Lifting
on forecasted precipitation
Forecast Tip:
If there is sufficient moisture in the air and a forcing
mechanism like a cold front (for example) is approaching
the area, then there is an increased probability that
precipitation will occur.
Clouds and precipitation are formed by the upward motion
of air. Therefore, there must be a mechanism present to lift
the air. Fronts often serve as such a mechanism. Air on
one side of the front typically blows in a different direction
from the wind on the other side, causing the air to
converge, or pile up right along the frontal surface.
How Does this affect me?
Convergence typical during Winter fronts
Convection typically during summer
afternoon over land and move towards
water-Less predictable
Can get a combination of both
Wind as a Predictor
Don‟t be fooled by direction
– Sometimes wind will head toward the storm
(Remember the convergence model)
Look at movement of the clouds
Dead calm in the presence of Cumulus
clouds indicate a severe thunderstorm soon
Wind direction coupled with different types
of clouds can be a good predictor
Lightning
If you hear thunder-High possibility of
lightning strikes at your position
Lightning can proceed the storm by a long
time
Just because you have blue skies doesn‟t
mean that you are not in danger
A number of strikes each year happen in
clear skies
From video of a distant cloud-to-ground strike near Gothenburg, Nebraska:
Frames 1 through 4 show the stepped leader descending
5 shows the intense first return stroke, Frame 6 shows the decaying first return stroke.
Strike Prevention
Lower antennas, fishing rods, outriggers
etc.. For a lower profile
Don‟t anchor near high items ie.markers,
buoys, power lines etc….
Get to safe haven asap…
Surviving a Strike
Have a bonded boat
Keep clear of metal structures on board
Wear rubber soled shoes
“Bonded Boat”
Major metal component are electrically
bonded to underwater hardware to create a
path for lightning discharge
Bonding is normally thought of a way to
prevent galvanic corrosion
Using heavy cable (8 gauge) gives a
adequate discharge path
Do‟s and Don‟ts in a Thunderstorm
Do slow down if visibility is poor
Don‟t anchor in a channel where you can be
struck by another boater
Do anchor from the bow is necessary
Don‟t anchor in a position where a slipping
anchor will put you in a worse situation
Do seek protected waters
FOG
Fog-
– Sea fog
Water is cold air is hot
You can look straight up and see blue skies
Can last all day and start at anytime
– Thermal Fog
Air is cold water is hot
Predictable
Will burn off after time
Fog
Using a audible signaling device-Preferably a bell
Proceed a speed based on your visibility
Zero visibility-HOLD your position
Use radar if you have it
Listen carefully for breaking waves, other boats
etc….
Have all the crew on watch in all directions
Have the crew report in reference to a clock (Bow
is 12:00)
Be SMART
Put lifejackets on early when conditions
deteriorate.
„It‟s better to be at the dock wishing you
were out rather than being out wishing you
were at the dock”
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