Winter Storm Threat: November 26 (Final Call)

Well, the model trends over the last 24 hours were not in the direction I though they were going to go, so I had to cut back the forecast along I-95 and make some smaller adjustments on the western edges of the contours. Overall, things have shifted slightly warmer across much of northern VA, DC, MD, NJ and southeastern PA in areas near and west of I-95. With such marginal temperatures of 33-36F at the surface, snowfall rates will be the big thing to watch tomorrow to see who will cash in and who will get stuck with little or nothing. Sloppy, wet snow for the major population centers along and near I-95.

20141126_MAsnow_final

The difference between 4 inches and 8 inches within that contour range will be elevation. Lower elevations can expect totals closer to 4-6 inches, with the higher elevations getting more into the 6-8 inch range. Along the Blue Ridge and Central Appalachians, a few of the higher peaks could hit 8+ inches. I didn’t include it on the map, but I wouldn’t be that surprised if there was one or two reports of 8+ inches in the highest elevations of north-central MD.

Some of the models even show some sleet mixing in, mostly from far northeastern MD into southeastern PA and NJ. That may actually be a blessing in disguise, as sleet can accumulate more easily than snow in marginal temperature situations, and a base of sleet would make it easier for any snow afterward to stick.

Forecast confidence remains on the low side, mostly with the eastern edge of the contours where the rain/snow/mix is the most problematic. A one or two degree change to the surface temperature could mean a big difference for some areas, both to the high side and the low side. There’s also still the question of where the best banding will set up, which will produce the heavier rates and increase the chance for higher accumulations for a select few. My best guess for that is just inside the eastern edge of the 4-8 inch contour up into the 8-12 inch contour.

Perhaps if we can get some big, fat dendrites cascading down along I-95, then that area could actually get a decent accumulation. However, looking at the temperature profiles, that seems pretty unlikely.


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