a busted forecast: what went wrong and why?

So, here’s a look at how much snow actually fell across our area from early Saturday morning based off reports sent into NWS. In all honesty, it was a bust for just about all of us as we expected widespread 4-6" and most only had 2-4". So why did this happen?

By far, the biggest problem we faced with this storm that caused reduced totals was it’s speed. Originally, we were thinking snow would last for 5-7 hours. But many of us were lucky to have snow falling for more than 2-3 hours last night. Even if everything else was off (warm ground, dry air, lighter precip rates), had we seen the snowfall rates we had last night for the forecasted 5-7 hours, this easily would have been a 5-6” event for many of you.

Surface temperatures were also a few degrees warmer than anticipated for a longer period of time. This led to snow melting initially as the ground cooled, so it took longer for snow to accumulate in some places. And finally, the storm tracked further north than expected. We knew there would be a band of 6-8”+ of snow somewhere with this storm, but it was about 40 miles further north than expected. So instead of northern MD getting the hammer zone, it wound up in south central PA and central NJ! This is where over a foot of snow fell in some areas.

So overall, it wasn’t the best forecast we’ve done. But it certainly wasn’t the worst. One thing we didn’t do this time that we should have was paid more close attention to surface observations, and not be so laser focused on model data. That’s something we definitely will keep on mind for next time.
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Forecaster Jack and the CMD team