In just the few hours leading up to the morning commute, snow may fall heavily and accumulate several inches in Washington’s far northern suburbs.

Over the rest of the region, a brief burst of snow could lay down a quick coating to a couple of inches pre-sunrise and into the early part of the morning commute, but the window for snow will be short.

AD

The snow may limit visibility and cause some slick spots, especially in northern areas, early Thursday.

This is a particularly challenging forecast, and small changes in the arrival of the cold air and intensity of the precipitation could make the difference between a snowy and rainy scene early Thursday in the immediate metro area.

AD

“The battle is on between how fast the cold air arrives and how quickly the precipitation exits the region,” Wes Junker, Capital Weather Gang’s winter weather expert, explained. “The farther north you are, the more likely that you receive meaningful snow and have your morning commute impacted. The farther south and east you live, the lower your chance of getting more than conversational snow. And you could just have rain.”

AD

Timing: Rain will overspread the entire region between about 10 p.m. Wednesday and 2 a.m. Thursday.

The changeover to snow will first occur in the mountains and far northern areas, between about 2 and 4 a.m.

In the immediate metro area and points south, if it materializes, the changeover to snow should happen between 4 and 6 a.m.

As all precipitation should end between 6 a.m. and 9 a.m. (from west to east) across the area, the window for snow from D.C. south will be quite short.

AD

Some snow could linger into the early part of the morning commute, especially along and east of Interstate 95.

Amounts: The snow will accumulate the most in Washington’s northern- and northwestern-most suburbs, which are under winter weather advisories. High-elevation areas will tend to see more snow than low-elevation areas.

Here are projected amounts:

AD

In northern Maryland near the Pennsylvania border: 3-6 inches

From northwest Virginia to north of Baltimore city: 1-4 inches

In northwest Washington, and D.C.’s immediate northern suburbs: A coating to 2 inches

In downtown Washington and within a one-county radius to the south: 1 inch or less

In the immediate metro area, while the window for snow will be short, the snow could fall heavily for a short time leading up to sunrise, and there is a non-trivial (1 in 3) chance that a quick thump of 2 to 4 inches could occur.

On the other hand, if temperatures are slow to cool — which often happens after very mild days — mostly rain could fall and little or no snow accumulation results.

Temperatures

When you go to bed (around 10 p.m.), temperatures may still be near 50 degrees in Washington, not particularly promising for snowfall. But models are consistent in forecasting a steady overnight drop through the 40s. They then predict a rapid fall between about 4 and 7 a.m. to near freezing, which is when snow could occur and briefly fall heavily.

Because snow could fall while it is still dark, it will ease the possibility of accumulation on grassy areas and even some slush build-up on the roads.

AD

AD

But if the models are too cold and the temperatures don’t fall off as they are predicting, this will turn into a mostly rain event for the immediate area, with perhaps just some conversational snow coating garbage cans and car tops before it all ends.

Storm impact: We’re rating this a Level One “nuisance” event on our winter storm impact scale in Northwest Washington, its immediate northern suburbs and to the north (within the metro region). This covers the zone on our accumulation map where we’re predicting a coating to two inches and one to four inches.

The relatively low rating is due to the fact temperatures are so mild ahead of the storm, most of the snow will fall prior to the morning commute, and the duration of the snow will be short. Still, some slick roads are possible in this area, and school delays or even closings cannot be ruled out — especially in our northern counties (Frederick and Howard counties).

By this evening, we will issue a SchoolCast.