Our forecast was pretty general, with a trace to the southeast of DC, a trace to 2 inches around the immediate DC metro, 2 to 4 inches to the north and west of the city, and 3 to 6 inches well out west. I would say overall that we were a bit low on accumulations, as Reagan National recieved 2.6" and numerous other locations had on the order of 3 to 4 inches around Fairfax, Montgomery and even Prince Georges Counties. The higest amount recorded was on Mt. Storm in Grant County, WV where they recieved 13 inches of snow. I attribute our forecasted totals being below the actual amounts mainly due to the very heavy band of snow that formed west of DC at the very end of the event. Snow rates must have been around an inch an hour if not more within the last band. This wasn't expected to happen, and if it didn't, then I think we would have been right on for accumulations.
Model grid interpolation forecasts were in the range of .6" of an inch of snow to 2.5" of snow for DC with the 10:1 snow ratio, which probably ended up being more like 13:1 or 14:1. This means for every tenth of an inch of precip the model puts out, you multiply it by 10 or whatever the ratio is in order to have a guesstimate of snowfall totals. It is often more in the very light fluffy snowfalls such as last night. We stayed on the lower end of the models as there was more of a consensus and trend towards lesser amounts. The GFS did, however, stay on the higher end, and this will be noted for future clippers and future storms this winter.
Now, for what we did relatively well. I think our overall snowfall prediction map was well laid out, as areas to the southeast did recieve only up to a trace, with more and more snowfall as you traveled north and west of DC. We also weren't THAT far off with accumulations, as we were only an inch or so off in most areas, so we are not too dissappointed. The timing also seemed like it was pretty well on target, as we had snow on our express forecast for 7am Wednesday throughout the day. The morning rush did seem to be a problem Wednesday morning though, so maybe we didn't communicate the possible problems as well as we should have.
Overall, this was a relatively weak system that crossed the region, but it had its challenges as well, and even tricked us some at the end with its final burst of snow. This is why I love forecasting the weather. There are a lot of challenges and sometimes you will be correct, but the weather is always changing and it is always a good thing to go back and check to see what you did correctly and what you need to work on. I will continue to blog after storms this winter just to share with you some of what we go through when making the forecast and the agony of waiting to see what actually happens.
