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Winter weather advisory western suburbs tonight; long-range winter storm possibility

* Winter Weather Advisory tonight Frederick (Md.) and Loudoun counties, midnight to 11 a.m. Wednesday *

In the battle of the seasons this March, winter is absolutely crushing spring. The latest jab from the Old Man is the possibility of a little freezing rain or drizzle overnight in our colder western areas. He’s then threatening to take a major swing at the Mid-Atlantic and Northeast coast in just over a week. Will he deliver a vicious, demoralizing blow or whiff?

Tonight’s freezing rain risk: marginal, at best

National Weather Service infographic for winter weather advisory

Some lingering cold air wedged into the region, just east of the mountains, combined with moist flow off the ocean could produce pockets of light freezing rain and drizzle in our far western suburbs overnight. In an abundance of caution, the National Weather Service has issued a winter weather advisory between midnight and 11 a.m. for Loudoun and Frederick (Md.) counties where a very light glaze of ice could develop – especially on untreated surfaces. The amount of precipitation simulated by models is underwhelming – at most a few hundredths of an inch – but just a tiny bit of ice can pose a hazard – hence the advisory.

NAM model simulates extremely light precipitation in western Virginia between 2 and 8 a.m. Wednesday morning. The freezing line at 8 a.m., in purple, cuts through central Loudoun and eastern Frederick counties. (

In the immediate metro region, temperatures should generally be above freezing, with just some spotty drizzle.  Still, those of you live in normally colder spots should look out for a little iciness early in the morning and use caution walking/driving.

Winter storm risk: a week from now?

As I discussed yesterday, there is fairly high confidence colder than normal air returns early next week (after a brief warm-up late this week). The computer models and their ensembles have been hinting there is the possibility of some sort of winter storm affecting the East Coast Tuesday-Thursday next week. At this point, the models seem to favor a bigger storm/snow threat for New England than the Mid-Atlantic.

The European model, in particular, predicts a major wallop for the Northeast. All of the operational models suggest a Miller-B type storm development, in which low pressure approaching from the west redevelops off the Mid-Atlantic coast. These kinds of storms are often extremely challenge to forecast in the D.C. area due to the possibility of getting caught in the dry slot. Here are snap shots of the storminess simulated by the GFS, Canadian, and European models.


GFS precipitation simulation Wednesday morning, March 26, suggest snow in D.C. as storm begins to explode to our east. (


Canadian model simulation, Wednesday night, March 26: the storm largely passes north of D.C. (Environment Canada)


European model simulation, Wednesday, March 26 after the storm has brushed D.C. with some light to moderate snow (

Of course, it’s way too early to talk specifics as the models will shift. But this is something to watch.

While accumulating snow is rare in D.C. at the tail end of March and requires a lot of different ingredients to come together, accumulating snow occurred on March 25 last year and our two biggest March snows on record occurred to close the month. So there’s precedent.

Jason is the Washington Post’s weather editor and Capital Weather Gang's chief meteorologist. He earned a master's degree in atmospheric science, and spent 10 years as a climate change science analyst for the U.S. government. He holds the Digital Seal of Approval from the National Weather Association.
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Jason Samenow · March 18, 2014

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