Weekend Snow Forecast: DC region expecting snow, wind and plummeting temperatures

WASHINGTON - Nine days. That's all that is left of winter. The spring equinox officially arrives next Sunday, and it seems that winter is determined not to go quietly. 

Friday will actually be a nice spring say with sunshine and temperatures reaching the lower 60s, but winter will begin to make its return after the midnight hour tonight.

Rain shower are likely to start overspreading the region east of the I-81 after the midnight hour tonight. Temperatures will likely be in the upper 40s and lower 50s around the region, so all rain is expected at onset. 

Rain will intensify as a storm system to our south begins to strengthen and push northwards towards our beaches. Saturday's high temperatures will be set before the sun ever comes up.

By the sunrise hours, temperatures start taking their tumble. The timing of this cool down will be absolutely key for how fast rain transitions over to a period of snow, but most weather guidance suggest it is likely to occur between 7-9am on Saturday morning along the I-95 corridor, earlier for those areas northwest of D.C. 

Rain will continue through southern Maryland and the eastern shore at this time, but will pick up in intensity.

By the mid to late morning hours, most of the region changes over to winterly precipitation, with snow around D.C. and the I-95 corridor, with some mix expected down across lower southern Maryland and the Northern Neck. 

Snow could come down moderate to heavy for a period of time. As we head into the afternoon, the system should start to pull away. Snow showers and perhaps a snow squall or two could remain into the early evening hours as an upper trough swings through the region though. 

Winds will get very gusty, potentially to damaging levels, with gusts over 50mph possible as the storm intensifies as it pulls away. Temperatures will continues to plummet through the evening and into the overnight hours.

Pinpointing accumulations is extremely difficult when we are talking about a rain-to-snow situation. It is twice as difficult during the month of March, when warm ground temperatures and a high sun angle can all impact how much snow is able to stick. 

With marginal temperatures past the transition, this will be a wetter variety snowfall. A lot of it will melt on contact, particularly on the paved surfaces. Accumulations will depend heavily on snowfall rates. 

Anything too light would just fall as a "white rain" that melts on contact, while heavier rates could add up to a slushy inch or two. Pre-treatment of roadways is not likely to be too effective, as rain overnight which could be heavy in its own right could wash away whatever salt or chemicals are on the roadways. 

While we are not anticipating bit probables on the major roadways, watch out for some of those lesser travel side roads to get a slushy coating. Thankfully this is all happening on a Saturday morning, when traffic is much lighter than a weekday.

Most areas northwest of town we are expecting 1-3" of snow, again mostly on grassy and elevated surfaces. Some scattered areas up that way could pick up more. Around D.C., we expect a coating to up to 2" of snow, and expect most of it will be confined to the grassy surfaces as well. 

That being said we do have a few weather models this morning suggesting that amounts could come in a little higher than expected. This morning's European (shown above) indicates the potential for more than 3" of snow in Washington, which would make it the second-largest snow of the winter if true. 

The National Weather Service is closely watching model guidance as well. They rely heavily on a model known as the NBM, the National Blend of Models, which is essentially a blend of model and ensemble guidance to create a forecast. 

Recent runs of this model have suggested as much as 2-4" in the DC region, with as much as 4-6" along the I-66 and I-270 corridors. This would likely be a high end, or "boom" scenario for snowfall across the region. 

But there is the threat that as the upper level features with this storm system swing through, there could be one more burst of heavy snow that might surprise some folks, and put down a quick inch or two. 

Winter Weather Advisories were issued this morning to cover those regions most likely to see disruptive snowfall accumulations. Parts of Montgomery, Loudoun, Howard, and Fauquier counties were all included in this advisory.

We suspect that D.C. and Baltimore will be included in a winter weather advisory update later this afternoon, based on some aggressive morning guidance that has come in. Winter Storm Warnings are in place for some of our mountain regions, where over half a foot of snowfall will be possible in elevated regions. 

While the snow will grab the headlines, one of the bigger stories with this storm will be the sudden drop in temperatures. 

They will fall all day on Saturday, and we will likely be in the 20s by sunset on Saturday evening. Winds will be extremely gusty, perhaps even damaging, as gusts could roar over 50mph. Wind chills if you are out and about on Saturday night will be in the teens and single digits. 

But Sunday, winds will start to lighten, but temperatures will plummet into the teens as skies clear out on Sunday morning. Sunday will be a winter like day, with temps in the teens to start and the 40s by the afternoon.

Speaking of the weekend, it is actually the last full weekend of winter! And that means it is time to kick those clocks forward one hour Saturday night before you head to bed. Starting Sunday, the sun will set after 7pm as we return to Daylight Saving Time. 

More good news in the final workweek of winter should feel a lot more like spring! 60s are back by Monday afternoon, and should remain there through next weekend and likely the week beyond as well. This storm really does look like winter's last wallop!