Forecasting the Weather

1
Forecasting the Weather
2
How is a weather forecast made?

• First data must be collected.
• Type of data (T,P, DP,W, Vis,RH,Prec)
• How collected
• Stations- surface observations (10,000)
• Aloft- balloons (radiosondes)(2X daily)
• Satellite (polar, geostationary (GOES))
• Planes, boats (7,000)
• Sparse over oceans and some land areas

3
(No Transcript)
4

• Second, data is analyzed.
• Agencies
• National Weather Service (NWS), part of NOAA
• World Meteorological Organization (WMO), part of
  UN (185 participating)
• Synoptic Weather Maps (aka-Surface maps)
• T, RH, P, Air flow (fronts, bars, precip, sky
  conditions)

5
(No Transcript)
6
(No Transcript)
7
Day 1 Predict for Day 2 3
8
Day 2
9
Day 3
10

• Third, forecasts are generated.
• Methods
• Numerical Weather prediction -forecast based on
  behavior of gases/physical laws
• Persistence forecasting -based on weather not
  changing
• Climatological forecasting - base future on
  climate
• Trend forecasting -extrapolate future based on
  current conditions
• P. 353 Box 12-2
• The forecast
• Ensemble forecast-several forecasts (each model
  with one changed variable)

11
Skill v. Accuracy

• Accuracy- closeness to being correct
• Skill- ability to forecast with accuracy that is
  better than climatic averages
• Ex LA (accuracy v. skill)
• In which areas of the country would it be very
  difficult to be accurate? Be skillful?
• Longer forecast time less accurate
• Why limited accuracy? (p. 365)
• To get the best forecast.