Calling all weather geeks! This story is for you. If you want just the headlines, you can find a less detailed story here.
The forecast is still on track to see some significant winter weather for your Wednesday, with snow, sleet, freezing rain and rain all in the mix. Winter storm warnings and advisories are posted for the region beginning overnight Tuesday and continuing through much of the day Wednesday.
A pretty strong area of high pressure parked over New England will continue to supply the Mid-Atlantic with cold air leading into Wednesday. A lot of the cold air will bank right up against the mountain ranges, keeping cold air close to the surface at least through the morning.
A warm nose of air will be moving in aloft from the south to the north beginning in the mid-morning, trying to erode the cold air from the upper levels of the atmosphere right down to the surface. This warm air will eventually win out, changing the snow to sleet and freezing rain, then to a plain cold rain. How quickly this happens will have a big impact on our snow totals from the south to the north. Cold air looks to hang on the longest from the eastern Panhandle of West Virginia and western Frederick County, Maryland, and north toward the Mason-Dixon line. This means these areas will have the potential for the highest snow totals across the region.
Warm air will continue to win out on Thursday, as a coastal low develops across the Carolinas and a warm front pushes north across the region. That means temperatures Wednesday night into Thursday are fairly steady, in the mid- to upper 30s, before rising through daybreak Thursday. Thursday’s temperatures soar into the 50s!
Tuesday will be completely dry, so do not expect any early dismissals or any evening events to be cancelled. The snow will begin moving in from the southwest to the northeast by daybreak Wednesday.
Wednesday loose timeline for planning:
Lunchtime: Changing to a mix
Just before dinner and after: Changing to a cold rain from south to north
Snow will be pushing into the region through daybreak and into the morning. All locations will see snow falling (and sticking) by 9 a.m.
The change to rain will happen through the late afternoon and into the early evening hours from the southeast to the northwest.
A cold rain will fall for almost everybody after 7 p.m. It could be moderate at times. There could be some isolated flooding issues.
Generally speaking across the area, locations south and east will be the first to change over to a mix and then to rain, while areas north and west will hold on to the cold air a little longer, leading to bigger snow amounts. We will still have to watch how quickly the warm air can move in, because obviously that will impact snow totals.
Right now we believe that warm air will start to spread north through the middle part of the day, bringing some ice accumulation on top of the already-accumulated snow. This process will begin to melt the snow into the overnight and turn into a slushy mess overnight Wednesday into Thursday morning. Rain showers will continue through at least the first part of Thursday, as temperatures move into the 50s, creating additional melting.
This will be an impactful storm. Once the first flakes start falling on Wednesday morning, it will stick immediately. There could also be some limited visibilities on Wednesday morning, in the thick of the snowfall. It could be fairly icy through the middle part of the day, before slushy conditions take over at night. Widespread school closures should be expected at least Wednesday, and possibly into Thursday (although it will JUST be rain on Thursday morning).
No more snow is expected as we head into the weekend. In fact, temperatures by Sunday should approach 70 degrees!