This web site compares the performance of the NAM, SREF, and GFS for the prediction of 24h accumulations of precipitation ending at 12 UTC. The European Center model (ECM) performance is included for projection hours 24, 48, and 72. The ECM forecasts are available to users in the U.S. later than comparable forecasts from NAM, SREF, and GFS.
The continental
US has been broken into 14 regions in consideration of approximate uniformity
of climatology and terrain. The verification was done on a 40km grid.
Graphical displays are generated for each region,
each of six projection times (24, 36, 48, 60, 72, and 84 hours), and each
of two time ranges (beginning one month and three months prior to the present).
There are a total of 156 graphics to look at. A new set of graphics is
generated every week.
Two measures of performance are displayed on each graph as a function
of accumulation threshold. These measures are computed from the following
traditional contingency table of event counts over a multitude of forecasts:








