An old adage taught to me in my Penn State days says “if the dynamics is there, the moisture will come” and does this ever apply to the impending Mid-Atlantic snowstorm. Initially, while computer forecast models consistently featured an impressive piece of energy in the upper atmosphere, there was very little moisture to show for it in the lower atmosphere. That has now changed dramatically in all computer forecast models and the end result will be a snowstorm on Tuesday throughout the DC, Philly and New York City metro regions and all the way to the coastline. [24-hour change in the GFS computer model forecast for storm precipitation (liquid-equivalent) totals are shown below with the legend (in inches); courtesy NOAA]
Snow is likely to begin in the early morning hours around DC, mid-morning in Philly, and mid-day in NYC. The snow will pick up in intensity within a few hours of the starting time and there will be an important impact on the evening rush hour in all areas. Snow winds down by midnight tomorrow night in the DC metro region, after midnight across Philly, and not until very early Wednesday morning in the NYC metro region. Snow accumulations by the end of the storm are likely to be in the 5-9 inch range in the DC, Philly and NYC metro regions (biggest storm in 3 years in DC). The snowstorm on Tuesday will be accompanied by falling temperatures as Arctic air floods the region from the north. Temperatures will likely reach the low-to-middle teens by day’s end in the I-95 corridor and then will bottom out in the single digits late tomorrow night – even in the big cities – and 0 degrees is not out of the question in some spots. There will be considerable blowing and drifting tomorrow night in the I-95 corridor as the storm intensifies off the Mid-Atlantic coast. Tomorrow will very likely be a snow day for most and there is even the chance that Wednesday will be as well given the expected brutal cold and all-night blowing and drifting.
The coastline from New Jersey to eastern New England will get pounded on Tuesday and Tuesday night with similar or even slightly higher snow accumulation amounts and blizzard-like conditions are likely at the coast during the latter stages of the storm. Brutal cold weather on Wednesday will be followed by a reinforcing Arctic shot on Thursday night, and then another bitter cold Arctic blast is destined to arrive in the northeastern US early next week. More on that later as the next week’s Arctic blast, originating in Siberia, could produce some incredible cold in the northeastern US.