Do not let these warm conditions fool you of the arctic snap that’s on our doorsteps today. With a very significant shift in the forecast trending towards the potential biggest storm in the region since 2019. Around this time in 24 hours, we will see a 30-35 degree temperature drop once the arctic front settles in from the north to the region.
The main focus mechanism will be a lobe breaking off from the Sub-Tropical Jet Stream that will begin to interact with the stalling out arctic front. The thermodynamic difference along this front will help generate a strong baroclinic forcing. An area of low pressure will begin to intensify later this evening and track just off the coast of the Carolinas. Moisture will then start running into the arctic air mass (overrunning) creating a fairly narrowband of moderate snow to overspread areas from central Virginia into the Delmarva region.
For a rare set of parameters, there has been exceptional agreement between ALL model guidance regarding several inches of snow to the region. Some big contenders like the ECMWF (European model) showing some fairly significant snow to the region. GFS being the most robust out of all them showing a foot plus. Although that’s being really extreme and not likely at this time, but we have a great average of 4-8 blend with all the guidance at this time. Subject to chance of course for the difference in small fluctuations on axis and location.
I get a lot of questions and concerns when it comes to the sudden temperature drop and ground temperatures. On the first onset of precipitation, intensity will be key. Just because we were in the 60’s the last few days, falling snow can quickly cool off ground temperatures with the heavier intensity of snowfall. Same with roadways. Snow will be beginning to fall during the pre dawn hours and continue into the afternoon hours.
Let’s not forget the night after if we have snow cover on the ground. With the arctic air mass settling in and fresh snow cover, temperatures will tank significantly during the overnight hours with clear skies. The snow will act as a blanket keeping the ground temperatures from warming the surface air temperature. Think of it like a cooler with ice in it, the air above the ice is extremely cold but underneath is above freezing. Depending on snow depth covering the ground, temperatures could drop down into the single digits.
We will continue to provide updates on this potential winter storm going into tomorrow.