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How much snow fell in D.C. and how was the forecast?

Snow over Washington, D.C. Monday night ( <a href="">Brian Allen via Flickr</a> )
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Roughly a coating to several inches of snow fell throughout the D.C. metro region between Monday morning and Tuesday morning – which was more or less in line with forecasts.

The snow primarily came in two phases:

1) A short burst Monday morning, that primarily impacted the District and points north. It put down about a coating in most places but up to 1 inch or so in our far northern suburbs. No snow accumulated in D.C.’s southern suburbs.

2) A second wave starting late Monday afternoon that continued overnight. Most areas received at least a half an inch from this wave – with generally 1 to 2 inches falling. However, a few localized bands produced upwards of 3 inches.

Officially, Reagan National received 0.6 inches from the storm, Dulles 2.0 inches and BWI 1.0 inches.

The heaviest totals I could find within a one county radius of the District were 4.5 inches in Germantown, Md. and 4.3 inches in Fairfax, Va. – where heavier snow bands set up overnight. Most locations were in the 1 to 2.5 inches range.

Link: List of snowfall reports from the National Weather Service

Here is a set of maps showing observed snowfall totals. Note that there may be gaps in coverage and some of these totals may not be final.

Northwest part of region: 1-4 inches

Northeast part of region: 1-3 inches

Southwest part of region: Coating to 3 inches

Southeast part of region: Coating to 1 inch

(All maps courtesy National Weather Service)

How was the forecast?

This was a very complicated event and one which I feel we did a solid job forecasting.

On Saturday, it appeared it would be a straight forward forecast, with a clipper passing just to our south, putting us in a sweet spot for cold temperatures and up to a few inches of snow.

But the forecast changed markedly Sunday, when the storm track shifted slightly north and it became clear the clipper would transfer its energy into a monster storm over the ocean. The shift north meant temperatures would be a little milder signifying snow during the first half of the storm would have trouble accumulating and could mix with rain (phase 1). The clipper’s energy transfer into a coastal storm meant the area would potentially be impacted by a “snow hole” or lull in precipitation during the day Monday as the clipper dissipated on its pass over us (phase 2). But then, the explosive development of the coastal storm meant we could have a period of snow as bands of precipitation wrapped around it and cycled inland Sunday night (phase 3).

The post we published Sunday afternoon laid this all out very clearly. Sure, you can find some issues with the specifics of the forecast. But we presented the big picture correctly.

We forecast each of the two waves to produce a coating to 2 inches of snow. Wave one produced on the low-end of that forecast, wave two on the high end. We correctly said the second wave would probably have a greater impact because temperatures would be colder. For the event overall, we forecast roughly 1-4 inches, and that was pretty much spot on.