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Posted at 11:50 PM ET, 12/13/2010

PM Update: Cold, wind, and a flake or two

By Ian Livingston

11:50 p.m. update: A narrow band of snow (or streamer), with some heavy bursts, is producing some light accumulations in Montgomery county and the District. The National Weather Service writes: "A band of light to moderate snow will affect areas mainly along and just either side of the Potomac between Point of Rocks and the District of Columbia...then further southeast from Oxon Hill to the mouth of the Patuxent. A coating of snow can be expected. Brief heavier accumulation cannot be ruled out along a line from Great Falls to downtown Washington to Brandywine..."

From 3:30 p.m.: Following this morning's light snow, today's stories have been cold and wind. Highs most spots occurred near midnight. There was some brief rise after sunrise, but temperatures falling back near and below freezing have been the tale of the afternoon. Sustained winds above 20 mph, with gusts frequently between 30 and 40 mph, have been common, and even higher winds have been recorded in Frederick County and to the northwest where a Wind Advisory is in effect until later this evening.

Radar & lightning: Latest D.C. area radar shows movement of precipitation and lightning strikes over past two hours. Refresh page to update. Click here or on image to enlarge. Or see radar bigger on our Weather Wall.

Through Tonight: We see variable clouds the rest of the day and through the overnight as winds remain pretty strong. There's also a risk of a passing flurry or snow shower, probably through the whole night, as persistent winds off the Great Lakes try to send a few flakes our way. Lows should settle in the very cold upper teens in the suburbs to lower 20s downtown.

Tomorrow (Tuesday): Another variably cloudy day defined by cold and strong winds. In fact, winds should be a touch stronger, which means a period of sustained winds near or above 25 mph with gusts past 40 mph possible. High temperatures probably struggle to pass 30 many spots, perhaps as high as near freezing downtown. This should keep wind chills in the teens and 20s much of the day. There could be a conversational flurry or brief snow shower as well.

See Jason Samenow's forecast through the weekend. And if you haven't already, join us on Facebook and follow us on Twitter.

Tonight's sky show: The Geminid meteor shower, an annual occurrence, peaks tonight. The good news is we may have some breaks in the clouds for viewing. Of course, you're going to need to bundle up big time! Frank Roylance of the Maryland Weather blog breaks down everything you need to know about the meteor shower, including its history and what time (near midnight) is best to watch for "shooting stars."

By Ian Livingston  | December 13, 2010; 11:50 PM ET
Categories:  Forecasts  
Save & Share:  Send E-mail   Facebook   Twitter   Digg   Yahoo Buzz   StumbleUpon   Technorati   Google Buzz   Previous: Charting 36 wind-chilled hours
Next: Scoop on wind & winter weather advisories


It has dropped five degrees in an hour in NW Montgomery. 25.2 now.

Posted by: MKadyman | December 13, 2010 3:57 PM | Report abuse

Wind chills in single digits late tonight.

Posted by: Jason-CapitalWeatherGang | December 13, 2010 4:00 PM | Report abuse

Whew! The wind is pretty wild right now in Silver Spring. It's starting to feel a tiny bit Syracuse-y out there! :) Unfortunately, I think I've lost my blustery wind tolerance after four years in balmy DC... this feels more unpleasant than I remember!

Posted by: CuseFan07 | December 13, 2010 6:16 PM | Report abuse

This is not really the best weather to go outside and watch for Geminid meteors tonight.

Posted by: FIREDRAGON47 | December 13, 2010 6:16 PM | Report abuse

Once again the 18z run shows a decent snowstorm hitting on 19th.

Posted by: StormChaserMan | December 13, 2010 6:36 PM | Report abuse

Yep, yep, StormChaserMan!

Posted by: Rcmorgan | December 13, 2010 6:40 PM | Report abuse

Hey CWG gang... what is the difference between GFS models and NAM models? Also, what is the difference between the 0z, 6z, etc? Thanks!

Posted by: PoorTeacher | December 13, 2010 6:54 PM | Report abuse

Another question... what is it going to take to the storm system that is moving through Thursday to shift north a bit? Or is this wishful thinking?

Posted by: PoorTeacher | December 13, 2010 6:56 PM | Report abuse

NW wind gusting to 44 at Martinsburg/Shepherdstown. There was a bit of a lull an hour or so ago, but then it came back with a vengeance. Tomorrow is forecast to be worse. Oooh boy.

Posted by: tinkerbelle | December 13, 2010 7:08 PM | Report abuse

Dec 19th of 2009 was our first major snowfall of 2009-2010 winter. Could the stars be lining up once again to rival the Dec 09 storm on the same day?? Talk about odds...or is there really some repetitive pattern scientist have not figured out yet. Look at Dec 5th snow events

Posted by: StormChaserMan | December 13, 2010 7:15 PM | Report abuse

PoorTeacher, the GFS and NAM are two different American models. The NAM is a mesoscale (small scale) model that mainly covers the United States and only runs out to 84 hours. The GFS is a global model that has less resolution and runs to 360 hours. They both have their strengths and weaknesses, to abundant to fully list here. In general, the NAM is best within 36 hours or so, and for things like t-storms, while the GFS can be a good indicator out to a week or so and often does well/better with larger storms (like a winter nor'easter). As far as 0z, etc. Read this.

Posted by: Ian-CapitalWeatherGang | December 13, 2010 7:44 PM | Report abuse

Awesome Ian. Thanks for the detailed write up.

Posted by: PoorTeacher | December 13, 2010 8:13 PM | Report abuse

0,6,18z refer to global time - greenwhich mean time. the model "runs" every 6 hours. so the 0z "model run" is for 0 greenwhich mean time (i.e. 7pm eastern time). i'm not at all a model expert, but i refer to the "gfs" as the "Good For Snow" model - seems to predict lots of snow...

Posted by: walter-in-fallschurch | December 13, 2010 9:13 PM | Report abuse

PoorTeacher, no problem. Though I mistakenly wrote the GFS runs to 360 when it runs to 384... at that range it's all make believe anyway. ;-)

Posted by: Ian-CapitalWeatherGang | December 13, 2010 9:51 PM | Report abuse

Some light snow into DC with lake effect... not super common to get a streamer looking so good into the area. Someone up in northern Loudoun etc might be picking up some accumulation if it holds.

Posted by: Ian-CapitalWeatherGang | December 13, 2010 10:48 PM | Report abuse

Street coated in South Arlington...bring on the apples!

Posted by: joshvt | December 13, 2010 11:32 PM | Report abuse

Actually snowing pretty well here in Bethesda. It just started so there's only .1 inches on the ground, but it's coming down well. Loving that streamer on the radar.

Posted by: nlcaldwell | December 13, 2010 11:49 PM | Report abuse

On the edge of the band in Cleveland Park but it's sticking fast. Seems someone right near downtown/Mall could do 'well' if it holds a while longer. Very fluffy.

Posted by: Ian-CapitalWeatherGang | December 13, 2010 11:52 PM | Report abuse

Um, nowcast please!! We're getting clobbered here in Georgetown.

Posted by: dickinyobooty69 | December 13, 2010 11:57 PM | Report abuse

Post just updated... A quick half inch possible in areas under this streamer band.

Posted by: Jason-CapitalWeatherGang | December 14, 2010 12:02 AM | Report abuse

Yup, a healthy accumulation in Georgetown. Half inch maybe?

That was fast. I just looked out into my garden and was shocked.

Posted by: Georgetwoner | December 14, 2010 12:07 AM | Report abuse

Snownirvana!! Streets, sidewalks, cars, lawns covered in Glover Park. Brisk wind, temp of 20 degrees. Best walk since Snoverkill. Just wish it would last all night long.

Posted by: JerryFloyd1 | December 14, 2010 12:17 AM | Report abuse

18.5F and a whole lotta nuthin' in Ashburn...not a flake to be seen.

Posted by: natsncats | December 14, 2010 12:39 AM | Report abuse

Why do they even bother to run it out so far? It's just not advanced enough to be accurate, and then you run into chaos theory (which I'm definitely no expert in!). It just leads to wishful thinking.

Posted by: KBurchfiel | December 14, 2010 12:41 AM | Report abuse

Georgetwoner, lake effect snow can pile up quickly.. not a lot of water content makes a lot of snow -- high ratios. Half of it might evaporate before the sun rises.. unless the band keeps moving around the area.

Posted by: Ian-CapitalWeatherGang | December 14, 2010 1:17 AM | Report abuse

We've got a nice light covering here in Gaithersburg, and it's still coming down.

Posted by: hawknt | December 14, 2010 3:46 AM | Report abuse

No flakes in the air or on the ground in Merrifield, VA. I'm hoping to see a shooting star when I leave to catch the bus, if I don't freeze solid first.

Posted by: --sg | December 14, 2010 4:10 AM | Report abuse

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