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Posted at 11:30 PM ET, 12/24/2010

Sunday snow odds continue to rise

By Jason Samenow

As new information comes in this evening and I digest it, I'll post updates every 30 to 45 minutes...

1:20 a.m. update: The bottom line: all guidance has trended toward a stronger storm, closer to the coast. This stunning shift cannot be ignored and the risk of a significant snowstorm on Sunday is real. The two operational models we trust the most - the European and GFS models - suggest the possibility of between several inches and up to a foot of snow. However, a slight shift in the track to the east could still result in little to no snow (1 in 3 chance) so this is NOT a done deal. On the other hand, any additional shifts in the track west could mean a crippling storm on a busy shopping and travel day. Considering all of this information, I think we have about a 60-65% chance of more than 1" of snow, and 35-40% chance of more than 4" of snow Sunday into Sunday night. We will have lots of coverage tomorrow, so please check back.

1:10 a.m. update: Euro has trended significantly west and suggests 2-4" or so for the D.C. metro region (but we are very close to getting a lot more or very little) Sunday, but much more toward the coast and a serious storm for southern New England. Give me a few minutes to digest everything I've seen tonight. I'll sign off with some final thoughts around 1:20 a.m.

1:00 a.m. update: Raise the roof, snow lovers. Euro looks like it may show a biggie... More in 10 minutes...

12:45 a.m. update: As we await the Euro, view this great video on the model evolution by Glenn "Hurricane" Schwartz in Philly - cut at midnight tonight: Big changes in snowstorm forecast

12:30 a.m. update: The average of the GFS ensembles (the GFS model run multiple times with slightly different initial conditions) also, taken literally, would suggest 6"+. But, again, the folks at NOAA who run this model think it may be overdoing things.

12:10 a.m. update:: NOAA says: "THE 18Z AND 00Z GFS RUNS ARE SHOWING SIGNS OF CONVECTIVE/GRIDSCALE FEEDBACK AS THE SYSTEM MOVES ALONG THE GULF COAST WHICH COULD BE MAKING ITS SOLUTION AT THE SURFACE AND ALOFT TOO STRONG." Translation: the GFS - which would, taken literally, indicate 6-12" of snow for the D.C. metro region - may be overdone. NOAA prefers a compromise between the NAM (dusting) and SREF (5" or so) - which would suggest a couple inches as most likely.

11:50 p.m. update: The Canadian model has also shifted slightly west from earlier runs but still just fringes the metro region with probably up to an inch or so but more toward the eastern shore.

11:40 p.m. update: A model from the United Kingdom, known as the UKMET, is now out. It suggests a near miss for the D.C. metro region with just light snow or flurries - similar to the NAM. However, its storm track is considerably west of earlier runs following the unanimous shift closer to the coast among all models today.

11:15 p.m. update: The latest guidance continues to support a storm track closer to the coast (further west), although the models have yet to reach consensus on how much precipitation will make it into the metro region.

Possibilities for Sunday still include just a dusting to 6" or more. The NAM model shows a glancing blow (light snow/flurries) whereas the GFS would suggest a major winter storm Sunday. The GFS is supported by the Short Range Ensemble Forecast (SREF) model which indicates about a 50% chance of five or more inches of snow.

In light of the latest model trends, we now believe there is a 50-60 percent chance of at least 1", and about a one in three chance of more than four inches.

However, we eagerly await the output from non-U.S. models (such as the Canadian and Euro) to see if there is more support for the snowier or drier solutions.

By Jason Samenow  | December 24, 2010; 11:30 PM ET
Categories:  Latest, Updates  
Save & Share:  Send E-mail   Facebook   Twitter   Digg   Yahoo Buzz   StumbleUpon   Technorati   Google Buzz   Previous: Update: Bumping up Sunday snow odds
Next: Winter storm watch Sunday & Sunday night


Posted by: FIREDRAGON47 | December 24, 2010 11:31 PM | Report abuse

I will now stay up another hour or so and follow your updates. Thank you...this is great!! (I'm such a weather geek!!:)

Posted by: BH99 | December 24, 2010 11:33 PM | Report abuse

also a good one!!

Posted by: BH99 | December 24, 2010 11:35 PM | Report abuse

Uh, is it just me, or is there a large batch of snow on the radar heading our way? Like, right now?

Posted by: KBurchfiel | December 24, 2010 11:36 PM | Report abuse

My parents need to drive from Frederick, MD to their home in Norfolk. Any idea about the onset of snow in Norfolk? Thanks!

Posted by: dettiot | December 24, 2010 11:38 PM | Report abuse

It does look that way!

Posted by: Alexandria2009 | December 24, 2010 11:38 PM | Report abuse

Jason - FYI - Hello from Boston, where I am visiting family for the holidays. TV forecasters are going for likely 8-12 in the city, possibly more depending on mixed precip towards Cape. But emphasis is on the uncertainty here.

Seems like we're all waiting for the next Euro run.

Posted by: afreedma | December 24, 2010 11:40 PM | Report abuse

argh, I was so happy when the odds were getting lower and lower. I'm supposed to be in Chesapeake on Sunday and then driving up to CT via Philadelphia on Monday. I have a bad feeling about the whole thing. Thanks for all the great info, keep it coming.

Posted by: ana_b | December 24, 2010 11:40 PM | Report abuse

@ KBurchfiel

I see what you are seeing also

Posted by: fortheglory | December 24, 2010 11:40 PM | Report abuse

Whens that Euro run coming out? I can't keep track.

Posted by: JTF- | December 24, 2010 11:41 PM | Report abuse

No pun intended...

Posted by: JTF- | December 24, 2010 11:42 PM | Report abuse

@fortheglory: I concur. It looks like we see things the same way.

Posted by: KBurchfiel | December 24, 2010 11:42 PM | Report abuse

Looking forward to the Euro and Canadian model runs.

This has been one exceptional ride, starting last Friday and continuing today. The storm has changed dramatically, from a "run of the mill" east to west over running type storm to a south east Atlantic "nor'easter". Watching the models last weekend and seeing the model consensus for a somewhat zonal type storm for Christmas eve to Christmas day disappear and evolve into this complex gulf of Mexico to northeastern coastal storm is mind boggling. It will be interesting to see the final break down of this storm and it's evolution through the week and the way the computers handled it.

Posted by: pjdunn1 | December 24, 2010 11:44 PM | Report abuse

CWG--I guess you had to clear the previous comment thread since it was bordering on inappropriate, but I really haven't laughed that hard in a long time.

Posted by: petworthlad | December 24, 2010 11:50 PM | Report abuse

CWG--I guess you had to clear the previous comment thread since it was bordering on inappropriate, but I really haven't laughed that hard in a long time.

Posted by: petworthlad | December 24, 2010 11:50 PM | Report abuse

whats up with this- ? looks like we could receive a little snow overnight? care to comment CWG?

Posted by: samd95 | December 24, 2010 11:51 PM | Report abuse

Lots of Virga on radar. Hopefully some of it will start to reach the ground in the AM. A white Christmas would be nice. Sundays storm looks legitimate. New JMA should be out soon. Euro will probably be out to sea, but I'm trusting the GFS runs at this point.0Z should have resolved the supposed data issues and still tended west.

Posted by: DLO1975 | December 24, 2010 11:51 PM | Report abuse


thanks for the gfs post link. how do you get to gfs links through the noaa site? And weirdly enough the site I use is still not showing a hit, the storm is still off to the east. But I feel like something is off with this because in terms of timing the gfs has the storm lagged about twelve or sixteen hours behind the NAM so I'm feeling like it's not updating.

Anywho I am also taking the gfs with a grain of salt. I want to see more support, but aside from model guidance, I don't think anything can really peg this one down.

Posted by: bbirnbau | December 24, 2010 11:52 PM | Report abuse

As forecasters, have you ever experienced this much uncertainty about a storm less than 48 hours in?

Posted by: samd95 | December 24, 2010 11:58 PM | Report abuse

Jason, how do the new models affect your probabilities? Is it too early for that?

Thanks so much to you and all of the CWG for your hard work!

Posted by: Spenny1 | December 25, 2010 12:09 AM | Report abuse


No. Craziest forecast. Ever.

Posted by: Jason-CapitalWeatherGang | December 25, 2010 12:10 AM | Report abuse

I hope this turns out to be a huge storm because then everyone will remember the forecasting madness! because if this is a bust, the whole ordeal will probably be forgotten

Posted by: samd95 | December 25, 2010 12:16 AM | Report abuse

Not gonna lie I'm staying up for the Euro. Does anyone have a link that will give it to me earliest? My site seems to be pretty primitive compared to the gadgets most of you fellows are working with

Posted by: bbirnbau | December 25, 2010 12:19 AM | Report abuse


To see the Euro in a decipherable format, it's going to be well after 2 a.m. I get the Euro starting around 1 a.m. - but I pay for it via a subscription service. I'll post what it basically shows.

Posted by: Jason-CapitalWeatherGang | December 25, 2010 12:27 AM | Report abuse

Merry Christmas/Happy Holidays first off 2 everyone, especially CWG team for all the awesome WORK you do!

Im a 34 year old snowlover who was spoiled like everyone last year...a huge dream come true!! Nooowww..I'm up..can't sleep..and waiting on every model run, hanging onto every last shred of hope the bloggers here give me!! Such a weather freak...and sooo glad we have this site

snowtorm, snowtorm, snowstorm! Waiting in Rockville

Posted by: Crazy4weather33 | December 25, 2010 12:30 AM | Report abuse


Nothing I've seen since 11:15 p.m. impacts the probabilities but the Euro run might.

Posted by: Jason-CapitalWeatherGang | December 25, 2010 12:30 AM | Report abuse


There is a lot of demand for the Euro output these days. Could you post the info to the subscription service for the Euro? That way we could decide whether we want to pay or wait for the info.


Posted by: pjdunn1 | December 25, 2010 12:32 AM | Report abuse

There seems to be a precedent for all this reluctance on the part of TV mets and model analysts to continue lulling us into submission with assurances of no more than a slight accumulation...followed by a real first-class pasting for this area...THE 1979 PRESIDENTS' DAY STORM!!!

[However if the models continue shifting us westward throughout the next 48 hours...sooner or later we'll end up on the "all rain" side of this particular storm!]

Posted by: Bombo47jea | December 25, 2010 12:36 AM | Report abuse


The fastest way to get access to the Euro is through I think it's $30/month. Tragically, the guy who ran the service passed away last month so not sure who is administrating the site.

Posted by: Jason-CapitalWeatherGang | December 25, 2010 12:36 AM | Report abuse

CWG - Thanks for staying up on Christmas covering this, although I guess this is as exciting as Santa coming for a lot of folks here. :)

I have to go out of town to Central VA (US 29 corridor, basically). Not too worried about conditions there, being farther west, but what does the TIMING look like for Sunday for whatever we might get here in DC?

My impression is that the timing has stayed consistent, but the track & intensity are what have wavered. Is that a fair assessment?

Posted by: vtavgjoe | December 25, 2010 12:42 AM | Report abuse

Thanks Jason!

Waiting for the 00z Euro to hopefully get some agreement in the forecast. This staying up late is killing me. Last year was bad enough.

Posted by: pjdunn1 | December 25, 2010 12:43 AM | Report abuse

anymore on what bastardi and berk are saying? I love all of the disscussion...i was in Kentucky in 2000 when I woke to the news that DC had gotten 10 to 12inches then...We were all shocked! I hope we get it again

Posted by: Crazy4weather33 | December 25, 2010 12:43 AM | Report abuse

Thanks for working late and keeping us up to date on the model runs. You guys always go the extra mile. Just wanted to wish you a happy holiday and let you know how much your hard work is appreciated!

Posted by: Chip_M | December 25, 2010 12:54 AM | Report abuse


Posted by: samd95 | December 25, 2010 12:58 AM | Report abuse


Posted by: Crazy4weather33 | December 25, 2010 1:02 AM | Report abuse


Posted by: oriolesfan2323 | December 25, 2010 1:05 AM | Report abuse

AHHHHH! The EURO did it!

Posted by: ChaseLuray | December 25, 2010 1:08 AM | Report abuse

Wow. Never give up! but this isn't over! And thanks for the GREAT coverage CWG, you guys are the best!

Posted by: samd95 | December 25, 2010 1:09 AM | Report abuse

It seems like the two storms meet around the Mid-Atlantic region. I think this storm looks big enough that if it hugs the coast we could see some nice snow.

Posted by: MVPlaya8120 | December 25, 2010 1:11 AM | Report abuse

hey Jason, just to confirm...any snow that might fall would be Sunday night and Monday mainly??

Posted by: BH99 | December 25, 2010 1:11 AM | Report abuse

I've got a flight scheduled to arrive for 8PM on Sunday - should I push my flight earlier to Saturday? Or earlier on Sunday

Posted by: GoodOmens | December 25, 2010 1:11 AM | Report abuse

Snow is fantastic. Capitol Weather Gang is fantastic. Glenn "Hurricane" Schwartz is super-fantastic. This event is ROCKING HIS WORLD. This is all so fantastic, right now.

Posted by: kumokasumi | December 25, 2010 1:13 AM | Report abuse

Euro!! Euro!! Euro!!

Posted by: mkbf26 | December 25, 2010 1:13 AM | Report abuse


Merry Christmas To All, And To All A Good Night! ;-D

Posted by: TheAnalyst | December 25, 2010 1:31 AM | Report abuse

You people are crazy. There, I said it!

Posted by: presto668 | December 25, 2010 1:35 AM | Report abuse

we are crazy but we LOVE IT

Posted by: Crazy4weather33 | December 25, 2010 1:44 AM | Report abuse

Just what did the Euro do?

Posted by: KBurchfiel | December 25, 2010 2:03 AM | Report abuse

Never mind. I should've paid more attention to the updates.

Posted by: KBurchfiel | December 25, 2010 2:12 AM | Report abuse

I think we may be getting close to calling another snowball fight in Dupont Circle - but what day should we set it - Sunday or Monday? And what time would be best? Join the discussion on Facebook!

Posted by: mlipin | December 25, 2010 2:13 AM | Report abuse

When you need a good laugh, visit the CWG!

Posted by: Rcmorgan | December 25, 2010 2:21 AM | Report abuse

I've been reading and loving CWG for about a year now and I have to say following this storm has been the most fun...even including the big ones last year! The roller coaster of emotions has been ridiculous, and now it looks like it might have a happy ending. 6z NAM looking good if not better than 0z GFS...only time will tell. Thanks CWG for staying on top of this...unlike local mets, TWC, even NWS.

Posted by: me4orioles | December 25, 2010 3:11 AM | Report abuse

Btw....Winter Storm Watch just issued for most of DCA and east -- calling for "possibility of 5 or more inches." Looks like they did catch on! We are in the game folks... sit back and enjoy.

Posted by: me4orioles | December 25, 2010 3:15 AM | Report abuse

Winter Storm Watch issued - ohhh Camden :)

Posted by: snowlover | December 25, 2010 3:18 AM | Report abuse

Posted by: MVPlaya8120 | December 25, 2010 3:40 AM | Report abuse

How much snow is likely if it continues to shift?

Posted by: adamma | December 25, 2010 3:51 AM | Report abuse

Another 20-40 miles west of where the GFS has us now has us well over a foot. As of now, I'd say 6-10 for DCA with localized heavier amounts east.

Posted by: me4orioles | December 25, 2010 3:53 AM | Report abuse

Awesome! I have been following the weather articles here for a few days now. I wish I knew more about the weather models but it's all so interesting!

I love snow! The more positive thoughts we have for it; then we will have it! I never gave up on the snow..even when they said it was a bust!

Now the NWS has just posted a "Winter Storm Watch" Warning and bumped the snow up to 70% chance on Sunday! Whoo Hoo! Only thing I hope is that people are safe and don't travel if they don't have to.

Come On SNOW!!!

Posted by: 882181 | December 25, 2010 3:54 AM | Report abuse

06z GFS slams us!!!! It is almost too good to be true!! I hope the GFS sticks because we will be well over a foot in DC and Bmore...

Posted by: snowlover | December 25, 2010 4:54 AM | Report abuse

Back to CWG after summer is snow time. Working my Christmas computer overtime. Perfect storm - perfect time! Hanging on every model run.

Posted by: Rjmw | December 25, 2010 5:10 AM | Report abuse

Something would have to go drastically wrong for DC not to get 6-12" or more.

When the GFS gets locked in like this so close to the event, it seldom is that far off. The snow/ no snow line is now depicted well west of DC, so even the western suburbs should get their fair share.

I would believe that the odds of 6" or more are about 80-90 percent.

Posted by: frontieradjust | December 25, 2010 5:16 AM | Report abuse

That is one wacky storm.

Posted by: ennepe68 | December 25, 2010 9:04 AM | Report abuse

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