Burst of snow could impact early morning commute for DMV Monday

WASHINGTON - Jan. 16, 2022 is not a date that will stand out to many, but it was the last time Washington, D.C. picked up more than an inch of snow. 

All the snow last winter – just 0.4 inches of it – fell on a single day: Feb. 1. This was the last time that downtown D.C. got any measurable snow. 

There is a chance, though just a slight one, that D.C. could put this 312-day streak to rest Monday morning as a burst of snow could greet early risers ahead of the Monday morning commute. 

Before we get to the snow part of the storm though, we have to talk about the rain portion. We are expecting a lot of it. 

Weather guidance is projecting between one and three inches of rain for the entire Mid-Atlantic region throughout the day. While temperatures may peak into the lower to middle 60s, Sunday is expected to be a washout. Rain could be very heavy during the evening hours as well. 

A flood watch is up for the D.C. and Baltimore metro regions through tomorrow because of this. Travels around our region expect slow traffic and very wet roadways, particularly during the nighttime hours.

As the system starts to pull away overnight, colder air will dive southward into the D.C. region from the northwest. 

Typically, this comes with drier air as well, which shuts off the precipitation before it can change over to snowfall. In this case, however, the parent trough driving the precipitation is trailing the surface front and the leading end of the colder air by a couple hundred miles. 

This means that as the colder air starts pouring into our region, there should still be enough moisture being thrown back over the frontal boundary to change rain to either mix or snow before the event wraps up. This is most likely to occur sometime after 1 a.m. on Monday morning, from west to east. 

There is a chance that early morning commuters in the pre-dawn hours could start their drives with snow falling. There is even the chance it could be briefly heavy in some spots, leading to slushy accumulations for a brief period of time.

That is the key to this event as well; temperature. D.C. has only hit the freezing make once during the first ten days of December, and that was just briefly on this past Thursday morning. 

Ground temperatures are not particularly cold. In addition, while it is true that we said that colder air will be coming into our region quickly during the pre-dawn hours of Monday, it will lag at the surface.

You can see in the image above, futurecast is showing widespread 30s Monday morning but it is not showing anyone below freezing. This occurs because colder air is coming in above our heads first, enough so that it falls as snow. 

When surface temperature remains above freezing though, it typically falls as "white rain" where it melts on contact. This can be overcome though if snowfall rates exceed the rate at which the ground can melt it.

Futurecast is suggesting that snow in a few places could come down briefly heavy enough to exceed the rate at which the ground can melt it. This would mostly occur on grassy roadways, though we would not completely rule out a slushy coating on some of the side streets in our region. However, it should be noted this would not stick around. 

Once the snow lightens and stops, the ground should quickly melt anything that did happen to stick. This should also occur all in the pre-dawn hours, with precipitation expected to exit the region from west to east around sunrise on Monday morning. 

As a result, we do not anticipate any major concerns with area schools. If someone happens to get a period of heavier-than-expected snow, I would not totally rule out a delay but this will be the exception rather than the rule. 

Most will not see snowfall impact their Monday plans. As you can see above, futurecast is not showing anyone around the immediate D.C. area picking up meaningful snowfall. Mountain zones are the exception as they often are, where high elevations could end up with several inches of snow.

The National Weather Service is in agreement that any bust of snow will be rather short-lived, and that most will melt on contact. 

They do note that, "there is a non-zero chance for accumulating snow further east, even near the D.C. and Baltimore metros. If the precipitation rates on the cold side of the boundary can be heavy enough well into the overnight this would take place." 

Much like we mentioned above, they agree that the probable solution is one that is not overly disruptive to Monday morning in our region. 

"The most likely scenario is for the boundary layer to remain above freezing while precipitation rates decrease as low-level drier air moves in toward morning" they wrote, meaning that they expected that the precipitation will likely wrap up before it can cause any significant issues in our region. 

As the chart above shows, they list D.C. and most of the I-95 corridor at about a 25% chance at seeing the first measurable snow of the year! It should be noted this snow is mostly expected in the pre-down hours, as precipitation is expected to wrap up around and after sunrise! 

Behind this front, we are in for a rather windy day on Monday and a very chilly workweek ahead. It should be a sunny and dry workweek ahead for the most part, however, with some of the latest guidance leaving us dry right through next weekend. 

Aside from the chance for flakes overnight, at this time, there is not anything else in the immediate future that shows the risk for winter weather. 

With the Christmas holiday now just about two weeks away, early forecast projections are showing a seasonally mild pattern around the Christmas holiday. Of course, if anything should happen to change, the FOX 5 Weather Team will keep you up to date!