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Ensemble Prediction System Products_ Interpretation_ and forecast

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					                  4th Ensemble Workshop Laurel MD May 2008s




     Overview of some
operational issues related to
         EPS data
             Richard H. Grumm
       National Weather Service Office
          State College, PA 16803
             Contributions from :
           Larry Struble, Pittsburgh
           Josh Korotky, Pittsburgh
           Chris Mellow Cleveland
          Justin Arnott Binghamton
              David Bright SPC
                         4th Ensemble Workshop Laurel MD May 2008s


                     OVERVIEW
• Training Issues, experiences and initiatives
  – NWS
  – Eastern Region
  – And beyond

• The Future
  – new data and forecasting
  – NAEFS/GEFS in GFE
  – SREF GFE
• Real world ensemble applications
  – Recent winter of 2008
  – Real cases affecting real forecasters
                    4th Ensemble Workshop Laurel MD May 2008s


           Training Issues
• COMAP-2008
  – Training on ensembles for new SOO’s
  – 2 full days from chaos to spaghetti
• State College-Pittsburgh
  – Sub-regional workshop in State College
  – 5 offices attended locally BUF-BGM-PHI-
    WBC-CTP
  – Remote offices Go-to-Meeting ER/SSD-BTV-
    OKX-LWX and CWSU Leesburg
                       4th Ensemble Workshop Laurel MD May 2008s


 Local Workshop 5-6 May 2008
• Requested by CTP operations team
  – Learn how to use the data better
  – Become more knowledgeable in these data
• Topics
  – Chaos and uncertainty from Mary Baxter (Central
    Michigan), Jim Hansen (Monterey), and Josh Korotky
    (WFO-PIT)
  – Products and forecasting –David Bright (SPC)
  – Basic products and statistics –Richard Grumm (CTP)
  – Local modeling and ensemble efforts- Justin Arnott
    and Mike Evans (Binghamton)
                       4th Ensemble Workshop Laurel MD May 2008s
       Personal Experiences
   Training and use of EPS data
• Effort Growing world wide
  – China, Africa, South America
  – Involvement in these activities provides cases
    and contacts (the high touch side of it all).
  – Local WFO’s and Universities
• Could be short window of opportunity
  – Exploit these data now
  – Training in Universities is slowly evolving as I
    learned visit St Louis University April 2008
                         4th Ensemble Workshop Laurel MD May 2008s
              Future and Data
              NWS perspective
• Importing NAEF/GEFS data into GFE (CTP)
  –   2m temperatures and winds
  –   Add value to the forecast
  –   Skill comparable to GMOS.
  –   Data provided by NCEP (Yuejian Zhu)
• SREF data into GFE (WFO-PIT)
  – Assists in complicated forecast problems
  – NAEFS/GEFS in GFE
  – SREF GFE
                  4th Ensemble Workshop Laurel MD May 2008s
             NAEFS Data
5km downscale EPS data aid in forecasting
       winds and temperatures
  4th Ensemble Workshop Laurel MD May 2008s


SREF Probability of Rain is copied
into Potential grid
(PotRainShowers grid)
                                   4th Ensemble Workshop Laurel MD May 2008s




3 hr PoP grid from SREF

•   PoP input to a local PoP grid can
    be from forecaster created PoP
    or SREF PoP grids
•   This figure shows the SREF PoP
    grid
                           4th Ensemble Workshop Laurel MD May 2008s



    Winter Precipitation Type Grids

   Procedure is especially useful when creating complex
    winter weather grids
   SREF PoP and SREF precipitation types can be easily
    merged into resultant weather grid
   Weather grid created from SREF precipitation type and
    PoP are coherent in space and time
              4th Ensemble Workshop Laurel MD May 2008s


             SREF Smart Init Probability
                     Snow




SPC Probability Snow
     4th Ensemble Workshop Laurel MD May 2008s


Probability ZR           SPC Probability
                              ZR
                        4th Ensemble Workshop Laurel MD May 2008s
        Real world ensemble
            applications
• Proving the value of EPS data to users
  – Around the world
    • China cold outbreak in January 2008
    • Korean floods August 2007
  – Within the NWS
    • Cases for impacted offices
    • Recent winter of 2008  provided many good
      cases to facilitate training, cases studies, and
      applications.
                                4th Ensemble Workshop Laurel MD May 2008s


Severe Weather 5-6 Feb 2008




 Figure Storm Prediction Center (SPC) storm report by type for the 24
 hour periods ending 0800 CDT on 6 and 7 February 2008. Reports
 are color coded by severe weather event type.
 http://www.spc.noaa.gov/climo/reports/ Courtesy of the SPC.
     4th Ensemble Workshop Laurel MD May 2008s


Snow fall Image
     4th Ensemble Workshop Laurel MD May 2008s


Surface and QPF
        4th Ensemble Workshop Laurel MD May 2008s
SREF 04/0300 UTC
has the big rain too
                               4th Ensemble Workshop Laurel MD May 2008s


     Korean Flood August 2007
• Ideal application of ensembles

   – Precipitation amounts (Probabilities) and timing provided excellent
     guidance of a significant event.

   – The probability of extreme amounts was high a clear sign to be
     cautious and aware of a big if not record event.

   – Meteorological setting
       • Intensity of key features associated with heavy rainfall.
       • Key features associated with heavy rains events
       • Climate anomalies of key features adding confidence to the
         forecasts and put the event into a meteorological context thus
         closing the loop.
                      4th Ensemble Workshop Laurel MD May 2008s
Estimate Rainfall valid 0000 UTC 10-14 August 2007
North Korean Flood GEFS forecast up to 14 inches of
                        rainfall!
       4th Ensemble Workshop Laurel MD May 2008s


PROB 100mm 48 hrs
                     4th Ensemble Workshop Laurel MD May 2008s


     Pattern Change in China
• Xu Xuan Jia Shenyang Central
  Meteorological Observatory, 11001
• Examination of cold and snow in China
  January 2008
  – Warm pattern turned very cold
  – Well forecast by Global Ensembles.
  – Good demonstration Case studies
        4th Ensemble Workshop Laurel MD May 2008s


Comparative Forecasts
                       4th Ensemble Workshop Laurel MD May 2008s

Midwest Floods 18-19 March 2008
• Big rainfall event
  – Most of it fell over 36 hours
  – Over the central Mississippi and Ohio Valleys
• Was particularly well forecast
  – Begs the question why?
  – Some extreme rain amounts for a cold season
    event.
  – Some large anomaly signals in the pattern
    too.
                                             4th Ensemble Workshop Laurel MD May 2008s


      Rainfall with the event




Figure 1. Observed Precipitation (mm) from the unified precipitation data set showing a) storm total
precipitation from 1200 UTC 17 March through 1200 UTC 19 March 2008 and b) 24 hour precipitation for the
period ending at 1200 UTC 19 March 2008.
                                         4th Ensemble Workshop Laurel MD May 2008s

Short range QPF for 3 inches




    Figure 14. As in Figure 12 except GEFS initialized at (left) 1200 UTC 17 March and (right) 1800 UTC
    17 March 2008.
                                                 4th Ensemble Workshop Laurel MD May 2008s


        The Pattern as forecast




Figure 1. As in Figure 9 except showing PW forecasts. Upper panels show each members 25, 12.5 and 6.75 mm contour
and the spread about the mean. Lower panels show the ensemble mean and the standardized anomalies of the
ensemble mean
                                4th Ensemble Workshop Laurel MD May 2008s


                    Case Studies
• Bring ensembles impact to users
  – Prove they can work any where then they can work here
  – Local cases get local offices interested
      • Louisville is doing a case Study on the Heavy rain events
      • LaCrosse on the Snow events
  – Western Region on the Big Jan 2008 winter storm (Salt Lake
    and Reno).
• Case studies
  – Great form of training and learning
  – Help users see the value and increase interest in using these
    data
  – And you get to interact with fun people
  – David Bright offers to help anyone do severe cases at the end of
    all of his talks!
                              4th Ensemble Workshop Laurel MD May 2008s


                         Review
• Training
  – There is a lot going on and it is getting better
  – Interest is growing
  – Case studies are a great training tool and incentive.
• The Future
  – NWS getting data into GFE to help with forecast problems
      • NAEFS/GEFS in GFE
      • SREF GFE  winter weather problem is but one
  – Will evolve more probabilistic forecast outcomes and products it
    is inevitable and it will be unstoppable.
• Real world ensemble applications
  – Case studies of big and significant events sparks users interest
    and will grow the use of ensembles
                         4th Ensemble Workshop Laurel MD May 2008s


          Acknowledgements
• Mentors Yuejian Zhu and Jun Du
• Input and ideas
  – ER/SSD
  – All those listed in the beginning who made
    contributions Larry Struble, Pittsburgh, Josh Korotky,
    Pittsburgh, Chris Mellow Cleveland, Justin Arnott
    Binghamton, David Bright SPC
• Others for great support and encouragement
  Zoltan Toth, Louis Uccellini, Robert Hart, and
  several individuals in the WMO and my local
  MIC Bruce Budd.

				
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