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Posted at 11:15 AM ET, 12/16/2009

You guessed it: Another weekend snow chance

By Dan Stillman

* Consistently cold: Full Forecast | Snow hype *

Updated: Wed. Dec. 16 @ 5:30 p.m. Potential impact increased by a half-flake.

Next Chance of Accumulating Snow: This weekend
Probability of Accumulating Snow (1" or more): 30%
Most Likely Potential Impact (as of now):

What is the deal with weekends and wintry threats? Two weekends ago we had the season's first snow, though areas north and west of town had a lot more to show for it than D.C. and south and east. This past weekend held the potential for a period of wintry mix, though we ended up with almost all rain. And now for this coming weekend...

We've been noting the chance of a coastal storm this weekend since Monday, and now that chance is good enough to consider the possibility of accumulating snow. At this point it is just that -- a possibility.

The culprit would be a storm emerging from the Gulf of Mexico on Friday and then expected to reform off the North Carolina/South Carolina coast on Saturday. Some models show the second storm forming and tracking close enough to the coast to bring precipitation to the mid-Atlantic or mid-Atlantic and Northeast while others do not.

With cold air expected to be well established both at the surface and higher up, any precipitation that does come this weekend would probably be in the form of snow or mostly snow. Most likely timing looks to be Saturday/Saturday night, though a Friday night start or Sunday morning end can't be ruled out at this point. Still too early to put any serious odds on different accumulation amounts, if any.

The Snow Lover's Crystal Ball appears when the potential exists for accumulating snow beyond 24 to 36 hours.

By Dan Stillman  | December 16, 2009; 11:15 AM ET
Categories:  Snow Lover's Crystal Ball  
Save & Share:  Send E-mail   Facebook   Twitter   Digg   Yahoo Buzz   StumbleUpon   Technorati   Google Buzz   Previous: Forecast: Consistently cold through weekend
Next: Say 'happy holidays' with a snowball


The latest NAM and GFS are trending towards 1-4 inches of snow for much of the region Friday night and Sat.

Posted by: AugustaJim | December 16, 2009 11:35 AM | Report abuse

RE: AW Hype... to me, the other graphic wasn't necessarily hype. At least they gave both scenarios and the GFS has show a strong trend of westward backing since I began watching it more closely. To me, this is hype, however:

Accuweather's Depiction of GFS snowcover for Christmas Day and Joe Bastardi hyping a white Christmas (scroll down for video)

Posted by: Registration1982 | December 16, 2009 11:39 AM | Report abuse

Well, Well, Well! Just yesterday you were bashing Accuweather for the hype machine and today you are now jumping on the bandwagon. I think an apology is in order.

Let it Snow!

Rainman Greg

Posted by: stinkerflat1 | December 16, 2009 11:40 AM | Report abuse

The trend lately is friendly for snow lovers in my opinion. Any more shifts west on the GFS and we get into pretty good precip (see total accumulated precip from 12z). Many storms this fall have "overperformed" in that aspect anyway.

Posted by: Ian-CapitalWeatherGang | December 16, 2009 11:43 AM | Report abuse

Re: hype -- First, going back to the comments in the AccuWeather hype post, why so many comments about the graphic being reasonable? While the AccuWeather graphic was included in the post as a visual, the point being made was -- quite clearly in the first line of the post -- that the story was headlined at the top of AccuWeather's website on Monday (not that the graphic was unreasonable), too far ahead of time to give that kind of play considering the lack of strong model support. Now it's Wednesday, 48 hours closer and with more model support, thus it's an appropriate time to bring more attention to the possibilities. -Dan, CWG

Posted by: CapitalWeatherGang | December 16, 2009 11:46 AM | Report abuse

To be clear, AccuWeather's identification of the potential for some snow this weekend wasn't the issue in my mind (we also saw the potential). I just thought they were overselling the threat 6-7 days out with a headline front and center on their web page.

Posted by: Jason-CapitalWeatherGang | December 16, 2009 11:49 AM | Report abuse

I am in complete agreement with Ian. I personally think this storm system is much more likely to over-perform than the converse. That being said, at least at this juncture, I don't see this being any "major" snow-maker. ...but, with average winter snowfall in the 15-20" range in this region, I could see it potentially putting down a quarter of that climatological seasonal amount.

Then again, this region seems to be specifically, almost purposely at times, set up to taunt, and give grief to, snow-lovers, so I think there's a 1/3 of no snow at all, at least downtown DC and areas north and west. Though I do feel quite confident that if we do see precipitation from this system, it will be in the form of snow and not rain...

Posted by: Josh-CapitalWeatherGang | December 16, 2009 11:54 AM | Report abuse

You can't really "reward" accuweather with praise for "calling it" early without encouraging further irresponsible early "calls". Being the first to predict usually means (in any area) that you simply make lots of predictions, many of which are wrong but people tend to forget.

Posted by: ah___ | December 16, 2009 12:23 PM | Report abuse

@ThinkSpring & AugustaJim: The expected precipitation maximum seems to run from Saturday night into Sunday morning, not Friday night into Saturday. This is a time period when few stores should be open and few shoppers out.

The interesting feature seems to be that little trough extension westward from the storm towards the Ohio Valley and Great Lakes. This trough may ensure that we get around an inch in light snow or snow showers even if the body of the storm misses us. It's uncertain whether this trough moves northward, southward or acts as a quasi-stationary boundary, but it could serve to advect some moisture into the cold air over us. Next week an upper-air low north of us may retrograde from the Canadian Maritimes towards the Great lakes, complicating the post-storm setup with cold air remaining in place. If we get six inches of snow or more out of this storm it could hang around through Christmas.

Posted by: Bombo47jea | December 16, 2009 12:37 PM | Report abuse

I want this thing to hold off until Saturday night!!!

Posted by: tengoalyrunr30 | December 16, 2009 12:51 PM | Report abuse

The precipitation maximum on the NAM, GFS and now GEM, which is also climbing on board, is late Friday night through Sat. afternoon. Look closely at the charts again.

Posted by: AugustaJim | December 16, 2009 12:54 PM | Report abuse

Yes absolutely Accuweather lives in the land of hype, but when you look at the cold-regime blocking pattern setting up over Eastern North America, this is exactly the way the maps look in the long range when a big storm does hit the mid-Atlantic. The GFS is especially good at seeing big storms from the long range. (Then it loses them in the 5-7 day period, then it waffles, then we'll see, but that's another story.) I am personally very bullish on a DC White Christmas and a big nor'easter is definitely not out of the question. To paraphrase that guy from McLean Bible Church on the radio: "not a forecast, just a thought." You can't possibly look at those maps and not suspect something's up, is my point.

Posted by: curtmccormick | December 16, 2009 12:55 PM | Report abuse

If you like snow, is being 'bullish' a good thing?

Posted by: authorofpoetry | December 16, 2009 1:45 PM | Report abuse

Guess I'll start my anti-snow dance earlier than planned.

Time frame would really hurt the retailers and curtail the Christmas shopping I've already put off for the last 2 weekends.

Posted by: ThinkSpring | December 16, 2009 1:49 PM | Report abuse

@ThinkSpring please leave. Your anti-snow dance is not welcome here. If you wish to have others join in your dance, you need to move North. Here in the south, we welcome snow the few times we get it.

Uptown, Down Home, Good Ole Boy

Posted by: Registration1982 | December 16, 2009 3:06 PM | Report abuse

curtmccormick, I agree in general about the pattern showing up in guidance and mentioned that previously in other posts. There are likely plenty of times similar has not produced an event, but it's also a pattern we tend to see with the big ones around these parts. Nevertheless it's tricky because there are several players that need to come together. I'm becoming more confident we can get some snow without a "perfect" situation for a big snowstorm -- for a few days it looked more "all or nothing" -- but there is also potential for a real nice event if it all works out right.

Posted by: Ian-CapitalWeatherGang | December 16, 2009 3:13 PM | Report abuse

so how many more runs until it's moved so far N/W that we are talking rain/snow and Fredrick gets the big hit?

Posted by: jpl1019 | December 16, 2009 3:22 PM | Report abuse

Traffic drops on weekends so there less warm air being pumped into the atmosphere.

It's like that summer of 2003(?) when it rained every afternoon at 5 and was gone by 7.

Posted by: anarcho-liberal-tarian | December 16, 2009 3:23 PM | Report abuse

for a substantial storm we just need the trough to tilt a little negative allowing the storm to ride up the coast. are there any indications that this will happen

Posted by: snowlover3 | December 16, 2009 3:25 PM | Report abuse

The 18z NAM is an epic snowstorm for parts of VA with a fair amount around here as well but sharp cutoff close by. Major precipitation just south... good spot at this range usually. Of course the NAM is often a little questionable several days out... though it has done decently of recent.

Posted by: Ian-CapitalWeatherGang | December 16, 2009 3:59 PM | Report abuse

The 18z NAM gives portions of Va. a foot or more of snow over the weekend, by bombing a 992 LP over Hatteras by late Sat.

At this point, not to be taken seriously, unless later support from other models.

Posted by: AugustaJim | December 16, 2009 4:07 PM | Report abuse

Ian, you tease!

Posted by: mcaicedo | December 16, 2009 4:45 PM | Report abuse

Thanks for the great posts. Agree with everything that was said - except for ThinkSpring - no offense :)- 1) "the trend is our friend" regarding a decent snow this weekend and 2) lots of times we get into a pattern like this without a storm. I was just saying that it's rare we get a big storm without this pattern. NAO is negative so I have hope. The NAM is awesome, but is just one map so far. But, things are absolutely getting interesting...

Posted by: curtmccormick | December 16, 2009 4:47 PM | Report abuse

My word----Looks like it could be A DECEMBER TO REMEMBER!!!!!!!

Time to go into full storm watch mode.

Posted by: stinkerflat1 | December 16, 2009 4:55 PM | Report abuse

My husband and I are supposed to head from Potomac, MD to Shepherdstown, WV on Sunday morning for 2 nights. Any ideas on how that might be impacted by this possible snow storm?

Posted by: TerpzFan | December 16, 2009 4:59 PM | Report abuse

I am still not 100% convinced of a storm. I want to wait and see the 18Z GFS model later today and then the Model runs tomorrow. I think we stand a 40% chance of a snowstorm. I really hope we get it!

Posted by: dante2 | December 16, 2009 4:59 PM | Report abuse

18z GFS looks pretty nice as well... low crawling up the coast. By 84 hrs most of the area .50" of precip or more, maybe more after.

Posted by: Ian-CapitalWeatherGang | December 16, 2009 5:03 PM | Report abuse

18z GFS gives much of our region 4 - 8 inches of snow.

Posted by: AugustaJim | December 16, 2009 5:16 PM | Report abuse

suppose to be going to nyc this weekend, is this looking like a southern storm or is it looking like it will move up the coast?

Posted by: bhfairfax | December 16, 2009 5:30 PM | Report abuse

Increased potential storm impact by a half-flake based on latest data

Posted by: CapitalWeatherGang | December 16, 2009 5:45 PM | Report abuse

**** - LET'S GO FOR FOUR!!! THIS IS GREAT NEWS!!! TWO snows is December and a possible storm as well around Christmas?!?!?! Keep us posted with evening updates. I will be sitting in my blue chair all night long waiting for updated from the CWG team - EL BOMBO - (WHERE IS BLUERIDGE MIKE?)- ~SPGLASS and other original members of the Capital Weather crew of groupies. BRING ON A THUMPING! BRING IT ON!!!

Posted by: stinkerflat1 | December 16, 2009 6:07 PM | Report abuse

Man I am becoming a model junkie! Not 5 minutes after the current model run comes out, I am looking forward to the next one. Problems.......

Posted by: snowlover | December 16, 2009 6:13 PM | Report abuse

Is it generally going to be worst south of D.C.? I'm supposed to go to Richmond/Appomattox this weekend... and I'd like to avoid a snowy drive if I can.

Posted by: hils | December 16, 2009 8:06 PM | Report abuse

Don't worry, Think Spring, I'll dance with you! After getting 4-5 inches two weeks ago, the N&W suburbs can take a pass this time...

Posted by: rumbly45 | December 16, 2009 8:15 PM | Report abuse

Okay, so we've got a possibility.

But if there's a miss, what's the result? No precip and cold? Or one of those "wintry mix"/"snow changing to rain" type of days?

Posted by: ah___ | December 16, 2009 8:49 PM | Report abuse

*snow dancing, dancing, dancing*

Posted by: manassasmissy | December 16, 2009 8:53 PM | Report abuse

Based on the latest info., what is the time frame that this system would get started within?

Posted by: bodyiq | December 16, 2009 9:02 PM | Report abuse

@ah___, a miss would result in either a little or no snow depending on how far it is off the coast but still cold. However, if the storm tracks closer to land than expected, we could get a decent snowstorm (10 inches or more). The models have been suggesting something in between those 2 possibilities but have recently been trending more snow. Unlike most snowstorms, people south and east can expect more snow and there will likely be a sharp cutoff line(D.C. could get 5 inches and Fredrick could get no snow, while Richmond gets 14 inches)

Posted by: samdman95 | December 16, 2009 9:08 PM | Report abuse

@Samdman95-thanks. I'd love the snow, but I'd rather cold and dry than cold and rainy. Looks like the model favors my wants!

Posted by: ah___ | December 16, 2009 9:36 PM | Report abuse


As one of the early contributors, I also wonder about Mike From The Blueridge?


Posted by: AugustaJim | December 16, 2009 9:38 PM | Report abuse

ah___ yup, very unlikely that we would get a cold rain unless the storm shifted extremely west, which is extremely unlikely (.3% chance)

Posted by: samdman95 | December 16, 2009 9:40 PM | Report abuse

Please keep in mind that this is only my *personal* opinion -- and not a consensus forecast by Capital Weather Gang; however, I am ready to pull the proverbial "trigger" on this storm and I feel quite confident at this juncture that all of the ingredients are coming together to produce at least a moderate snowfall for the DC metro area. I think a solid 3-6" is a good bet with...[why do I know I'm going to regret this??] 6-12" within the realm of possibility. Giddyup!

Posted by: Josh-CapitalWeatherGang | December 16, 2009 9:41 PM | Report abuse


Posted by: AugustaJim | December 16, 2009 9:42 PM | Report abuse

Samdman's comments align with what NBC25 (Hagerstown) was saying on the evening news. Lou Scally also mentioned some Christmas Eve potential but downplayed this weekend's storm which could track away from areas farther inland. However, this HPC map seems to suggest otherwise...

Stinkerflat, I am glad you are in full storm mode. By the way that zit video of yours is pretty gross!

Posted by: spgass1 | December 16, 2009 9:46 PM | Report abuse

Do the northeast suburbs (east of 95; north of the Beltway) pose to do?

Posted by: edwardappleby | December 16, 2009 9:46 PM | Report abuse

Not outlandish with this setup, Josh. Looks more and more like a very solid storm for someone around here or close by. The new NAM is great and still room to trend a bit more northwest (as is often the case -- though it might not happen here). This pattern is beautiful if it comes together right.

Posted by: Ian-CapitalWeatherGang | December 16, 2009 9:48 PM | Report abuse

Let's go 6-12 inches! Based on the west trend, what concerns to you have for mixed precip in the Dulles Area? In addition, if you have to choose an area to do best? Where would that be?

Posted by: CMan62 | December 16, 2009 9:54 PM | Report abuse

everyone, there is almost no chance for mixed precip or rain in the dc area, we either get snow or we dont but we wont get anything like a cold rain or mix

Posted by: samdman95 | December 16, 2009 9:56 PM | Report abuse

Possibility of enough snow to play in? Must....remain....calm.....

Posted by: Snowlover2 | December 16, 2009 9:56 PM | Report abuse

YEEEEEEES here we go. Newest NAM still has good storm

Posted by: jmc732msstate | December 16, 2009 9:57 PM | Report abuse

samdman95, you are right. Very surprisingly for DC, I don't we're going to have to deal with a rain/snow line in the immediate metro area. In my opinion it's either snow or no -- but mixed precip (let alone rain) unlikely to be part of the equation...

Posted by: Josh-CapitalWeatherGang | December 16, 2009 10:00 PM | Report abuse

i think this warrants 3 flakes! lol

Posted by: samdman95 | December 16, 2009 10:00 PM | Report abuse

I am also curious about the Dulles area. I am worried we are too far west to get the brunt of this storm. We did have a great snow with the last one(6 inches in Herndon) but I have to admit I am getting a bit greedy.

Posted by: justin1013471 | December 16, 2009 10:01 PM | Report abuse

what is the newest GFS showing?

Posted by: samdman95 | December 16, 2009 10:04 PM | Report abuse

fyi, our percent chance for accumulating snow is almost sure to go up in our posts tomorrow, pending review of tonight's data. but how high? tomorrow morning ye shall find out

Posted by: Dan-CapitalWeatherGang | December 16, 2009 10:05 PM | Report abuse

So some people are saying Friday night and others are saying Saturday night. I'm just curious when it is supposed to get started at DCA. I have a flight Saturday morning.

Posted by: amorris525 | December 16, 2009 10:08 PM | Report abuse

I'm heading down to Charlottesville on Saturday afternoon. Are they looking to get even more than us, at this point?

Posted by: jburksva | December 16, 2009 10:08 PM | Report abuse

this could be a good-very good storm depending on how close to the coast it is. the best part is that we will get more snow than new england

Posted by: samdman95 | December 16, 2009 10:09 PM | Report abuse

Re: GFS, It is not running yet.

I think one thing the NAM showed nicely is what a high pressure block near Greenland can do for you, with some help from a trough headed negative. I would not say it's a done deal it happens this way, but several models show a near-stall of the surface low in varying spots(see NAM: 60hr | 66hr). The NAM has snow of varying intensity through Sunday.

Posted by: Ian-CapitalWeatherGang | December 16, 2009 10:12 PM | Report abuse

If all the ingredients come together, does this storm have more potential than 12+ inches in the DC area?

Posted by: CMan62 | December 16, 2009 10:25 PM | Report abuse

If models still show a good storm in 48 hrs or less it will be time to get excited. More than 48 hrs out r 2 iffy. Now if models hold up thru noon Thur. then good things might happen 4 us snow lovers.

Posted by: VaTechBob | December 16, 2009 10:28 PM | Report abuse

Ohhh so excellent!!!!! This weekend if we have a storm I will be reporting from around the area as the unofficial correspondent on the street. This is me with Mike Seidel of The Weather Channel on December 5, 2009.

Posted by: stinkerflat1 | December 16, 2009 10:31 PM | Report abuse

whoa, first, snow was Sunday (in time for our reskedded xmas parade), then I hear Saturday, now it's Friday night? Lordy, will it snow all weekend? Will it hang around until Santa arrives? Will we all be able to still shop for Christmas? Is it time to stock up on **** gasp **** those unmentionable items? (M-B-TP?)

Posted by: weathergrrl | December 16, 2009 10:34 PM | Report abuse

Have a birthday party to host - what do you think will be happening Sat. in Gaithersburg, say 4-6pm????

Posted by: Post43 | December 16, 2009 10:40 PM | Report abuse

Every model run is looking better and better... I think if all of tonight's runs look good, then it'll be "milk, bread, and TP" time at all the local stores by Friday.....

Posted by: SkywalkerSS | December 16, 2009 10:52 PM | Report abuse

The GFS looks quite similar to the NAM in many regards and actually stalls the low out nearby for longer. It's still running but is showing a very nice storm for sure.

Posted by: Ian-CapitalWeatherGang | December 16, 2009 10:59 PM | Report abuse

Drat, had go buy a sports car that has summer tires on it and dump my 4x4 Explorer last spring...

Unfortunately for me, if it does dump this weekend anywhere along the I-95 corridor, people are going to put of leaving town for the holiday pushing them back to when I am going to be on the road heading south.

Posted by: FusilliJerry1 | December 16, 2009 11:08 PM | Report abuse

More snow south and east, maybe? Nice - considering I live in Alexandria (and my exam will be over by tomorrow night!) I've been skeptical, now I'm becoming more optimistic... need to let my roommates know as I got called out for not telling them about the storm potential last weekend! Guess that makes me an official weather geek! :)

Posted by: MKoehl | December 16, 2009 11:15 PM | Report abuse

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