Better Forecasting Bureau An Introduction to Forecasting By: Joe Finlon & Steve Travis

Current Conditions Always check current conditions first Look outside! Check out satellite and RADAR (weathertap.com) Check current obs, METAR Atmospheric Soundings (SPC)

Look Back! Check what’s been going on the last couple of hours This can help forecast what may happen in the next couple hours

Look at Models (the computer type) NAM (Forecast hours 0-60) GFS (0-240) ECMWF WRF (0-48) RUC (0-12) SREF

NAM Good for some larger mesoscale features Good for basic temperatures and precip Time resolution every 6 hours Larger scale 80km grid North American domain

GFS Long time scale (as much as 16 days) Only actually good out to ~7 days Spectral model Global scale Covers the same phenomena as NAM

ECMWF European model Like the NAM, but better Most accurate model overall Costs money, so we don’t have it

WRF Smaller time scale than NAM and GFS Higher resolution Good for mesoscale processes Handles lake-effect well Good for winds

RUC Short range forecasts Updates every hour Good for initial analysis and nowcasting

SREF Combination of many different models Good for general weather trends Not good for precise forecasts Currently last in forecast game rankings

What to look for Upper level heights (300, 500) This gives you an idea of troughs and ridges Look at winds for jet streams and divergence Must look at upper levels to get an idea of what’s happening in lower levels

Lower Levels Mean sea level pressure and winds Temperatures Look for surface highs and lows Temperatures Precipitation 10m winds

Temperature forecasting Look at winds (10m) Cloud cover (RH 700-900mb) Mixing from higher levels Precipitation Dew points

Precipitation Precipitable water Amount of water in the atmosphere Plot precipitation (compare different models)

Prepare a forecast Make a forecast for 6z tonight and 18z tomorrow Temperatures at each time Precip amount at each time (6 hour precip) Winds