An exercise in forecasting

Forecasting methods Basis: start with persistence –Yesterday’s weather will occur again today Then ask questions: –Will there be any differences between yesterday and today? –What will the surface conditions be today? –What will the upper-level conditions be today? –Where were today’s air parcels yesterday?

Forecasting tools Begin with yesterday’s weather –Surface conditions temp, moisture, wind direction/speeds –Upper-level conditions 500 hPa troughs / ridges 300 hPa cloud cover 850 hPa temperatures –Examine surface maps, satellite images, and the most recent sounding

Yesterday’s weather worksheet Temperatures in Graz –High: Low: –Average dewpoint: Extent of cloud cover

Now for today Temperature –High temp expected –Low temp expected (tonight) Cloud cover –Portion of sky obscured by cloud Current weather –Expected precipitation & type

Longer range Use computer forecast models –UKMet (from England), GFS (from USA), NOGAPS (from USA) Interpret output from these models, arrive at forecast