The featured chart has a lot going on and taken from a newly added IEM autoplot that combines recent daily Growing Degree Day (GDD) observations along with two NWS forecasts. The chart is for Des Moines and shows the past eight days of GDD observations [green bars/line] along with a seven day forecast from the NWS National Digital Forecast Database (NDFD) [red] and a single deterministic forecast from the NWS Global Forecast System (GFS) [blue] out sixteen days or so. The climatology is shown by the floating black bars and line. Whew, so what is the point of all this? There isn't much optimism to be found that we'll see significant GDD accumulations over this period. Almost all the daily data is well below average and the accumulated values for the GFS model on 10 May is about half of average. It certainly did not help that the most recent weekend saw 0 GDDs for a base 50 degree calculation.

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Tags:   gdd