The Perils of Long-Range Forecasting

6:15 pm in Forecast Discussion by Ted Keller

I thought you might enjoy looking at these maps.  Each shows surface highs and lows (black lines, isobars), precipitation areas (green) and a rough approximation of temperature (dashed lines).  Each is a forecast or projection valid on noon Wednesday.  The difference is each computer model ran at different times with different input.  There are four over a 24 period run at 6pm last night, Midnight, 6am today and noon today.

Notice that a radically different weather pattern is painted over Missouri and Arkansas on each “run”. One has high pressure and no precipitation, two have us in chilly air with a hint of light precipitation and still another has low over St. Louis!

It is no wonder that trying to get an exact handle on the forecast for the days leading up to and including Thanksgiving is very challenging indeed.  Which model run is right, if any?

From Thursday Noon Run

Thursday 6am Run

Thursday Midnight Run

Wednesday 6pm Run