We often talk about looking at different models while forecasting. These data fields make a new run (or data set) every 6 hours. Between Candice, Eric, and I we can look at 6 different models at any given time. We look for consistency between the different models as well as consistency between each new run.
For example, the two images above are 6 hour precipitation totals from 1pm Sunday until 7pm Sunday. These two models are completely opposite of each other. The one on the right (GFS) is painting over a quarter of an inch of rainfall, while the other (NAM) is staying completely dry.
Now for further analysis. This is the first time that the GFS model has fired up storms for Sunday afternoon. Before jumping at the chance of rain during this time period we would like to see the GFS model continue to bring in the wet weather, as well as have some of the other models fall in line with its thoughts.
Next comes previous experience. Typically the GFS model overdoes precipitation. For example, Thursday night the GFS model was going for 0.50" of rain in some areas across the Stateline. The Rockford Airport recorded 0.06" of rain. One would then think that, the GFS model might be overdoing the rainfall chances for Sunday afternoon.
I just wanted to let you in on the thought process that we go through in predicting rain during a busy holiday weekend... -ADAM
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