Temperatures have crashed from the 50s and 60s into the 40s and 30s across the region as of 5pm this evening. As we head later into the overnight hours, enough cold air will filter in that precipitation will change to freezing rain and sleet before finally changing to snow in the early morning hours.Temperatures as of 5pm
At this time, it appears the changeover to freezing rain and sleet will occur first north of D.C. closer to 10pm and the D.C. Metro by 11pm or Midnight. Looking at some of the latest models, light sleet may accumulate for a few hours before a changeover to snow by 4-5am in the D.C. Metro. The change will continue by 6-7am south of D.C.HRRR Forecast Composite Reflectivity for 1am Monday (Courtesy: WeatherBell Models)
The heaviest snowfall accumulations should occur from 7am through Noon, with the potential for snowfall rates of 1-2" per hour. So when you wake up tomorrow and do not see very much snow on the ground, don't be shocked. There will still be plenty of slick spots with sleet and light snow through the early morning, so major travel disruptions are likely. Temperatures should be in the 20s by sunrise tomorrow.
Snow should hang around through the early afternoon before exiting by the early evening. By the time this system departs, we think a general 4" to 6" of snow will be possible in the D.C. Metro and points north to the Mason-Dixon line. South of D.C., higher amounts are possible, with 6" to 10" as our range in those locations. Isolated spots may even see higher amounts.Snowfall Potential through Monday Afternoon
The 4" to 6" range in the Metro and points north seems plausible given higher precipitation totals as of late have shifted south of D.C. It appears some of the heavier precipitation will enter areas such as Culpeper, east to Fredericksburg/Stafford and Southern Maryland. This is where we have set of the 6" to 10" zone. Our thought is that plenty of cold air will be available when the heaviest precipitation enters the region.
Something to note, however, is if that band shifts a mere 30 miles to the north, the Metro could receive some of the higher totals. This is something we will be watching very closely as the system evolves.
There is also the potential for sleet to hang around a little longer, which could potentially hamper snowfall accumulations. This will be something else we will be keeping in mind.
Regardless, this is a high impact event with travel disruptions and plenty of cancellations.