PM Update: Falling temps tonight ahead of big snow on Tuesday

* Winter storm warning Tuesday for entire region *

Temperature Map

Temperatures: Latest D.C. area temperature map. See interactive map on our Weather Wall.

Today might not have felt too much like the lead-up to a snowstorm given high temperatures ranging from the low-to-upper 50s across the area. A strong cold front located to our north and northwest will move into and through the area overnight though, setting the stage for a significant snowstorm tomorrow. The morning commute should be less ugly than the one home, but it’s going to be a rough weather day for anyone other than snow lovers on Tuesday.

Note: We will do a special live blogging of the model runs tonight starting around 9 p.m.

Through Tonight: Clouds increase overnight, but that may not be too noticeable initially depending on where you are. While there’s a way to go back to and below freezing, most in the area should get there sometime in the hours surrounding midnight. We’re mainly in the upper 20s to low 30s for “lows” before snow breaks out and colder air continues to filter in. That snow should be moving in out west in the pre-dawn period.

Tomorrow (Tuesday): Snow is pushing into the area from the west as we get toward 5-7 a.m., sweeping east across the entire region by 10 a.m. With temps near and below freezing to start, snow should accumulate right away (except perhaps for a brief time downtown, and near Potomac, Bay). For most of the heart of the area, the heaviest activity comes in the midday/afternoon to early evening time frame. Periods of heavy snow (up to 1 inch or more an hour) are possible. Snow then winds down as we get through the evening. When it’s said and done, a general 4-7 inches or so is likely. At this point, model simulations would suggest the high end of that range (or even a bit higher).

Related: Significant snowstorm Tuesday, with widespread 4″ or greater amounts


Capital Weather Gang snowfall forecast first call, issued 12:45 p.m. Monday.

Temperatures that start out marginal for snow accumulation in the city (morning lows ranging from the upper 20s to near freezing) should drop throughout the day, through the 20s as time passes. By evening, most spots should be in the teens to low 20s or so. Winds are also gusty throughout, increasing to around 20-25 mph sustained in the mid-to-late evening, causing wind chills to be lower and periods of near whiteout visibility possible.

See Jason Samenow’s forecast through the weekend. And if you haven’t already, join us on Facebook and follow us on Twitter . For related traffic news, check out Dr. Gridlock.

SchoolCast:


Entire D.C. region:

2.5 apples: Good chance schools close pre-emptively, even if snow is not falling early in a.m. Do your homework to be safe. An exception might be D.C. schools where this may be closer to a 2 apple event (50/50 chance of closure)

FedCast:


2.5 domes: Good chance of unscheduled leave/telework policy; shut down less likely


Wind speeds in knots from this morning’s GFS model, predicted at 7 p.m. tomorrow. Overall, the windiest is east of the area, but strong winds are likely here as well. (Weatherbell.com)

Winds and blowing snow: With both the Arctic air rapidly pouring into the region and a developing low offshore, winds are likely to whip much of the day, and especially near  sunset to around midnight. Further to the east along the coastline, some spots may actually get near true blizzard conditions. As we get deeper into the event, snow will become fluffier while winds pick up. Even in places that “only” see sustained winds reach the 20-25 mph zone, with gusts near and past 40 mph, blowing and drifting snow could become issues along with reduced visibility. While you’ll want to take it easy driving in the area most of Tuesday, once the sun goes down things could get extra ugly/hazardous for a while, even as snow ends.


(Graphic by National Weather Service)

 

Ian Livingston is a forecaster/photographer and information lead for the Capital Weather Gang. By day, Ian is a defense and national security researcher at a D.C. think tank.
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Jason Samenow · January 20