Another week, another winter storm. Once again, the New York City and Philadelphia metropolitan areas are under the threat for a major winter storm that has the potential to produce snowfall totals over 6 inches throughout the entire Northern Mid Atlantic and over a foot of snow in some locations from central New Jersey on through Connecticut.
The first piece of this dynamic storm is currently moving towards the Southeast coast producing snow, sleet, and rain from Georgia all the way into Virginia. The second piece of this storm is currently over the central Plains producing snow from northern Oklahoma through southern Minnesota.
Over the next 24 hours, these two disturbances will phase into an intense dynamic winter storm that will batter much of New Jersey, southeastern New York, and Connecticut with near blizzard conditions while much of eastern Pennsylvania will experience a moderate to heavy snowfall as well. The way this storm is setting up, a band of intense heavy snowfall will develop along the coast from central New Jersey on through Connecticut. Along the immediate New Jersey coast and southeastern Long Island the snow will mix with rain and sleet at times making for an icy mix on Tuesday night, however even these locations will change over to all snow.
The key factor to understand with this snow storm is the way the low pressure system bombs out off the New Jersey coast on Tuesday night into Wednesday morning. As the low pressure system intensifies, cold air will be pulled towards the coastal waters making for a very tight thermal gradient at the surface up through the upper levels. This creates a highly unstable atmosphere where convective snowfall can develop. Convective snowfall can create some rather wild snowfall totals for the region with some locations stuck in between bands thus receiving far less snow than expected while other locations are stuck under heavy snowfall for hours leading to snowfall totals over a foot in localized regions. Meanwhile further to the west over much of Pennsylvania, this type of lifting along the coast tends to reduce the snowfall rates even with higher snowfall ratios. As the bands intensify to the east, the snow shield over Pennsylvania will break up a times and could even end early. This is why the snowfall forecast has far less snowfall amounts expected west of the Delaware River.
This snow is expected to start as scattered snow showers on Tuesday afternoon. The very dry air in place will create virga, which is precipitation that evaporates before reaching the ground, through Tuesday afternoon. You’ll know virga is happening even without a radar as skies will be overcast and temperatures will start to fall. If you are outside you’ll feel a bit of a chill in the air, kind of like when you just get out of a hot shower and the cold air rushes in. As the afternoon and evening continues, the virga will end and the snow will start lightly after 3 PM over southern New Jersey as scattered snow showers and then increase in intensity as the evening continues. The snow will overtake the entire Northern Mid Atlantic after 7 PM and will increase in intensity.
Along the immediate coast, temperatures will warm slightly into the lower to mid 30’s leading to a mix of snow, sleet, and rain. This mix will be from the coast to roughly 10 to 20 miles away from the coast. Thereafter the atmosphere is far too cold for anything but snowfall. Along the immediate coast on Tuesday night, when heavy bands of precipitation moves over, the precipitation will be sleet and snow due to the intense lifting cooling the atmosphere. However when the snow and sleet decreases in intensity, rain will mix in as the lower atmosphere warms slightly due to sinking air. This process will end by midnight with all snow expected for Wednesday morning.
Further northwest from central Monmouth County on northeast through the New York City metropolitan area, central Long Island, the southern Hudson Valley, and all of Connecticut; at this time this is where I expect the best mesoscale banding to set up with all snow expected. The snow will be of the heavy, wet variety to start however snow ratios will drop as the storm bombs out and cold air is drawn to the east. These locations will be at the focus of intense bands of snowfall with even the potential for thundersnow. At this time I can not pin point what locations will receive the most snowfall, but there is clearly a threat for over a foot of snow in these locations.
Again, further to the west including the Philadelphia metropolitan area, snow will be heavy at times but will be impacted by the influences of the intense snow bands to the east, thus snowfall amounts will range from 6 to 12 inches along the Delaware River and 4 to 8 inches to the west with far less amounts towards central Pennsylvania.
The snow map for this storm can be found here.
After this storm exits on Wednesday afternoon. Cold and windy conditions can be expected through the end of the week with temperatures averaging well below normal.
For more details, please visit the NY NJ PA Weather Local Seven Day Forecast!