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Posted at 05:05 PM ET, 12/18/2012

White Christmas tracker, December 18: Are snow chances hopeless in Washington, D.C.?


Simulation showing cold fron through the region Friday morning at 7 a.m. with perhaps a few snow flurries north and west of D.C. (National Weather Service)
We’re now a week from Christmas Day - within the range models begin to have some accuracy and the details of weather systems start to take shape. Yesterday, we said White Christmas odds were down. Today we can’t quite say they’re out.

Cold air bursts into the region Thursday night and someone - mainly west and north of the beltway - could see a snow flurry into early Friday morning. But that snow - for sure - won’t stick around until Christmas.

As we’ve discusssed for some time, much of Friday through Monday will be mostly dry in the immediate Washington, D.C. and Baltimore metro regions.


The GFS model simulates no snow on the ground in Washington, D.C. at 7 p.m. on Christmas Day. However, it shows plenty of snow over the western slopes of the West Virginia highlands and mountains of western Maryland (WeatherBell.com)

But if you head into western Maryland or the west facing slopes of the West Virginia highlands, significant snow is possible. Winter storm watches have been posted for late Thursday night through Saturday evening where 6 inches or more snow is likely. These places should have a White Christmas.


The European model simulates light rain moving during the second half of Christmas Day. However, sometimes it underdoes low level cold air, so we cannot rule out a mix or even some light snow at the onset. (StormVistaWxModels.com)
Throughout the region, Christmas Day is *likely* dry. However, some (a minority of) model guidance wants to bring a storm system into the region by the second half of the day. This guidance would suggest precipitation would come in the form of rain or perhaps an icy mix at the onset. But, a period of snow cannot be totally ruled out if it’s a little colder than forecast.

Most model guidance holds the storm system off until December 26 or 27 and favors mostly rain or a wintry mix changing to rain. But forecast details remain very difficult to pin down.

In short, the scenario for us to get snow Christmas Day would be for the storm to move in on the fast side of model simulations with more cold air than they currently suggest. The odds of this are very low, probably around 5 percent. There’s hardly any scenario where the storm would move in quickly enough for one inch of snow to be on the ground Christmas morning, meeting the formal criteria of a White Christmas.

But snow lovers at least can hold on to the very slight hope the storm moves in fast enough with cold enough air to fill the air with flakes for a time on Christmas Day.

While we continue to think a later arriving storm with warmer air is far more likely, we will, of course, keep you posted.

By  |  05:05 PM ET, 12/18/2012

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