Dear Tom,
Why do forecasters show the four “models” of weather predictions beyond their own estimates? I’ve seen rain estimates that range from .85″ (NAM) to 1.59″ (GFS), with EURO and GRAF “guestimating” in between 1.23″ and 1.15″, respectively.

Steve Bloome, Bolingbrook

Dear Steve,

Weather forecasting is far from an exact science, and the various models available to meteorologists often yield widely-diverging outcomes. Over time, it has been proven that consensus often delivers the best forecast as a middle-of-the-road approach. In many rain or snow events, the forecast model ranges and extremes often end up describing the totality of the precipitation event across the area from highest to lowest. Often, an average of the model extremes comes close to the city’s official total.

GOT A QUESTION FOR TOM? Ask him here!