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Posted at 10:30 AM ET, 12/25/2010

Update: Winter storm watches extended west

By Jason Samenow

The entire metro region - including western suburbs such as Loudoun, Fauquier and Frederick counties - are now under the winter storm watch Sunday and Sunday night.

The light snow falling this morning, likely to produce only a dusting or so, is not part of the storm expected tomorrow. Rather, it is associated with energy along the northern jet stream that is expected to merge with a disturbance along the southern jet stream to produce tomorrow's powerful coastal storm.

Most model guidance which has come in since last night continues to show a high likelihood of moderate to heavy snow tomorrow and tomorrow night. One model - the NAM - suggests more of a glancing blow so we don't have 100% consensus. However, our winter weather expert Wes Junker says: "I don't trust the NAM output and think it may be having problems. I'm pretty bullish for this event."

The Short Range Ensemble Forecast Model, from 4 a.m. this morning, indicates better than a 70% chance of 0.5" of liquid for the metro region (with even higher probabilities toward the Eastern shore. This would equate to 5" of snow.

Based on the guidance we have reviewed, we now believe there is better than a 70 percent chance of at least one inch, and better than a 50/50 chance of more than four inches. We will provide more fine tuned predictions in our next update after reviewing some more information. The Short Range Ensemble Forecast model indicates better than a 70 percent likelihood of at least 0.5" of melted precipitation which equates to more than 5" of snow.

We are getting a lot of questions about flights tomorrow given it is a very busy travel day. We expect snow to begin late tonight, with the possibility of moderate to heavy snow during the day. The snow could linger into the evening hours. There is a significant chance of flight delays and cancellations tomorrow into early Monday morning, especially as this storm is likely to impact the I-95 corridor from Richmond to Boston. However, there remains a small - but not trivial chance - that the storm just skirts us.

Ultimately, decisions about making changes to flights are up to travelers based on the flexibility of their schedule and the forecast information we provide, which is necessarily uncertain. It's hard for us to make specific recommendations about whether to change flights.

We'll have more confidence in the forecast as the day progresses to help you make decisions so stay tuned for additional updates...

By Jason Samenow  | December 25, 2010; 10:30 AM ET
Categories:  Latest, Updates, Winter Storms  
Save & Share:  Send E-mail   Facebook   Twitter   Digg   Yahoo Buzz   StumbleUpon   Technorati   Google Buzz   Previous: Forecast: Snow likely on Sunday
Next: Update: Still big range in Sunday snow potential


I love it !!!!!!!

About time things started to shirt back in our favor. (crosses fingers)

About when can this new update be expected? Will it be the normal 1:30 time?

Posted by: SnowDreamer | December 25, 2010 10:41 AM | Report abuse

Thanks for all the updates! So, how many of us bought snowblowers after last year, and were told that meant it'd never snow 'bad' again? I'm one of them and here we go! :-)

Posted by: BoaterVA | December 25, 2010 10:43 AM | Report abuse

Hey Capital Area Gang guys, with less than 36 hours to go for the event, you should consider sticking your neck out and coming out the a snow accumulations forecast.

Posted by: krishnanswamy | December 25, 2010 10:43 AM | Report abuse

I woke up in the middle of the night and checked the CWG website and saw the renewed forecast for a snowstorm. Although that news is like a lump of coal in my Christmas stocking, I want to compliment CWG on your diligence and keeping us aware beyond the conventional forecasts.

Posted by: david_in_stafford | December 25, 2010 10:43 AM | Report abuse

Thanks for all the repeated updates during Christmas morning! When you all are able to (and no rush as it is Christmas people), what is the max we could get?

Again, thanks for keeping us all posted and thanks to your family for allowing us all to "steal" you.

Posted by: hereandnow1 | December 25, 2010 10:45 AM | Report abuse

This is an historic comeback! We snow lovers were down for the count. Gonna enjoy every moment!

Posted by: jaybird926 | December 25, 2010 10:47 AM | Report abuse

CWG - Thanks for all your extra time spent on this holiday conundrum. What an excellent blog this is.
That forecast model map makes me laugh. Of course no one can accurately forecast this thing; the entire coast is right on the hairy edge.
Seems likely that those near the ocean will get walloped. The rest of us will have to press our noses up against a window & wait.

Posted by: FIREDRAGON47 | December 25, 2010 10:49 AM | Report abuse


We'll put out an accumulation outlook by early to middle part of this afternoon.

Posted by: Jason-CapitalWeatherGang | December 25, 2010 10:50 AM | Report abuse

Just when you post this most promising update yet....the gfs comes out and gives us just under 2 inches of snow.

I knew I should not have gotten my hopes up

Posted by: bbirnbau | December 25, 2010 10:58 AM | Report abuse

Latest GFS has backed off huge totals of last two runs... and would suggest 3-6" type event rather than 6-12" type event. We'll have another update soon.

Posted by: Jason-CapitalWeatherGang | December 25, 2010 10:59 AM | Report abuse

Thank you CWG for all the updates! We really appreciate all your efforts to keep us informed. CWG is the best!! Still flurrying here in Montgomery Village- so pretty!

Posted by: soleil2000 | December 25, 2010 10:59 AM | Report abuse

Ok so I was just looking ata the NAM by mistake. WWWWHHEW!

Posted by: bbirnbau | December 25, 2010 11:01 AM | Report abuse

@ Jason/CWG--

Thanks so much for the updates. We do appreciate it.

We're in Rappahannock County, VA, right up against the Blue Ridge. If possible, when you put out your accumulation outlook, please comment on accumulation levels as you move west from D.C. Thanks much.

Posted by: NorthFork1 | December 25, 2010 11:02 AM | Report abuse

Does anyone know what the deal is with ? I followed the discussions there during the 09/10 events, but now I can't get it to come up on a variety of browsers and platforms - no error message, no nothing. Has the site been taken down altogether for some reason or moved to a different URL?

Posted by: snowpro | December 25, 2010 11:02 AM | Report abuse

So flight coming in 9am tomorrow to DCA has a high likelihood of being canceled? Or is the morning looking OK?

Posted by: GoodOmens | December 25, 2010 11:02 AM | Report abuse

Do appreciate all you guys are doing, even though I'm freaking out due to travel plans tomorrow.

Any chance you can post a timeline of accumulations as best as you can? Not for the whole east coast, I'm thinking for National Airport, LOL!

Posted by: Post43 | December 25, 2010 11:04 AM | Report abuse


Posted by: samd95 | December 25, 2010 11:05 AM | Report abuse

Yeah it looks like a bit of an eastward shift but i honestly expected that. I was not convinced that we were going to see the totals that NY or Boston would see. This is more in support of the Euro. But no matter how much the models say anything the fact is the way this thing is working I strongly believe snowfall predictions are impossible to make, even this close to the storm. Just like Jan 2000 I don't think anyone really knows what's going on here. The models are changing with every run. My gut tells me we're going to see a 2-4 incher but I just can't put any confidence in that

Posted by: bbirnbau | December 25, 2010 11:06 AM | Report abuse

Merry Christmas, all! A few things:
1. CWG guys-- Listen to Mom here. Spend some time with your loved ones today! And that means without a laptop attached to your side. ;o) There, I said it.

2. I will most likely be disregarding #1 above, because I for one will be hanging on your every word. I'm monitoring the forecast so I can give the in-laws the best advice concerning travel to MoCo tomorrow to see brother in law/sister in law. I also have a "Boxing Day" lunch with my side of the family out in Bristow, which will entail a drive down Rt 234 from beautiful downtown Dumfries.

We now return to your regularly scheduled Christmas Day mayhem (considering there's a 7 year old and a 17 year old in the house!).

Posted by: southbridgemom | December 25, 2010 11:07 AM | Report abuse

Folks- We can't take specific questions about flights because we really don't know the answer and you've got to make that decision yourself. What we can say is what's in the post above - that there's a good chance of snow tomorrow - starting in the morning- and a chance flights could be disrupted. Personally, I would not be changing flight plans now but waiting until this evening when we'll have better forecast information to help with decision making. The forecast remains a bit uncertain.

Posted by: Jason-CapitalWeatherGang | December 25, 2010 11:09 AM | Report abuse

I no sooner hit the 'post' button and the update comes up saying the models have shifted east again. Geez, talk about fickle. I wish they'd make up their minds already!!

Posted by: southbridgemom | December 25, 2010 11:10 AM | Report abuse

Easternwx has closed down, most of the people running it started a new site.

The euro has the best scores overall in the time range we're in so the new GFS may be onto something despite my bullishness which was mainly based on the 09Z sref ensembles and on the 500h pattern. Not a good storm for a supposed winter weather expert.

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

@snowpro has moved to

Posted by: Jason-CapitalWeatherGang | December 25, 2010 11:11 AM | Report abuse

Easternwx is now here

Posted by: pjdunn1 | December 25, 2010 11:11 AM | Report abuse

Thank you so, so much CWG for the updates despite the holiday.

Here's hoping you have some egg nog to help through the data analysis.

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

I'm not travelling anywhere so don't have travel concerns but still want to say thanks for all the work and updates. Merry Christmas.

Posted by: marathoner | December 25, 2010 11:12 AM | Report abuse

@snowpro looks like the site was shut down... If you google the site name and 'shut down' you'll see references to it on several other forums.

Posted by: BoaterVA | December 25, 2010 11:12 AM | Report abuse

A general question for CWG and others who know: what inputs would make the models this fickle/flaky/variable? It seems like a heck of a lot of change for a few hours of additional input.

Are they on the edges of some tipping points and wobbling back and forth?


Posted by: BoaterVA | December 25, 2010 11:20 AM | Report abuse

I am not sure how accurate the models are, but with the tight precip gradient a small track variance could mean the difference between getting 3" and 15"! I have a feeling this is going to be a wait and see type storm. Even when CWG comes out with an accumulation map, a mere 50-75 miles could decrease or increase the totals by 50%.

Posted by: snowlover | December 25, 2010 11:23 AM | Report abuse

Merry Christmas from the Blue Ridge east of Front Royal. We picked up 3/16ths of an inch this morning... combined with leftover snow from 12/16/2010, it is almost a white Christmas from the appropriate angle.

Special thanks to CWG for their tireless forecasting.

Posted by: spgass1 | December 25, 2010 11:24 AM | Report abuse

Hi BoaterVA /Lee, the storm's POTENTIAL energy is scattered across the United States right now. The mathmetical imputs that intialize each model seem to be drawing EXCEPTIONAL disagreement when comparing all of the global forecasting models. The phasing-together of the energy pieces across the United States may or may not happen. And, well, CHAOS THEORY seems to be reigning strong. It is very frustrating, but I think it simply has been a while--and we are being reminded--that mathematics in such a dynamic atmosphere can output MANY options from the same intial sets of data (weather balloons, surface weather station reports) from around the globe. ooof!

Posted by: Camden-CapitalWeatherGang | December 25, 2010 11:25 AM | Report abuse

Merry Christmas, CWG guys! All of y'all ROCK! Thanks for all you do, especially on a day when just about everything is shut down and quiet.

Personally I'm hoping for lower accumulation totals...some of us have to work tomorrow!

Posted by: natsncats | December 25, 2010 11:29 AM | Report abuse

@Camden Thanks much! I guess we'll have to see how quickly/if they lock in! Should be a very interesting 12-24 hours...

Posted by: BoaterVA | December 25, 2010 11:30 AM | Report abuse

In regards to the airlines, my very humble opinion is that the airlines will try to fly as many flight as they can tomorrow. They don't want to be dealing with a long backlog of passengers if they don't have to. 5" of snow total is nothing for any carrier and it isn't a major problem for the local airports. There will be de-icing delays, but shouldn't be much else.

Frankly, you're apt to be delayed more for where the aircraft is going (or arriving from) than anything happening locally....which means anything going to/coming from NY/BOS may be in some jeopardy tomorrow. The rest of the nation looks pretty clear.

Just an opinion from somebody who flew 120k this past year :(.

Posted by: singleseatbiggermeat | December 25, 2010 11:37 AM | Report abuse

So I'm in North Carolina and the local meteorologists here with their own locally-produced models are calling it.

6" here is as bad as a foot or more there, and to me this has the scent about it of our 2001 "bombogenesis" storm that left 20 inches on the ground.

Just like this storm, no one was expecting it so no one prepared for it.

What I need from y'all is as close to a bottom line as you can get -- I'm feeding your data to friends and family scattered along the east coast to make them aware of what no one's paying attention to yet. What time do we need to start making our way back to the District if we want to get there before the snow starts flying?

I'm thinking this could be an utter disaster along 95 for drivers if it plays out the way the NC mets and foot's forecasters are talking. Let us have percentages of likelihood from miss (which I think is not likely since all the people I read are in consensus) through Snowmageddon (the second storm "last" year). I'd prefer worst case scenario numbers at this point because I'll decide what to tell them (and what to do) based on that.

Thx. And again, I bow down to the winter weather gods.

Posted by: AdmiralX | December 25, 2010 11:52 AM | Report abuse

I know it's kind of unfair to compare Virginia to Vermont, but I flew up to Burlington last January right after they had gotten about 30 inches of snow (a record for them). No problem for the airport or the airline. If we landed on snow, we landed on snow.

Not saying that Dulles, a major international and national airport with multiple large runways, can pull off the same feat. But they certainly don't have to pull a Heathrow.

Posted by: KBurchfiel | December 25, 2010 11:54 AM | Report abuse

I was reading the americanwx discussions. Do I follow this right that while D.C. is still up in the air (not a major hit), that SE and E of DC is still a bigger hit (eg. NAS PAX @ .75 qpf)?

Posted by: somdcommuter | December 25, 2010 11:54 AM | Report abuse

2 things-
1. can you guys do what you did last nite with the short blurbs about each model every 30 mins?
2. When do you guys stop looking at the models and start looking at the radar?

Posted by: samd95 | December 25, 2010 11:58 AM | Report abuse


Yes--you're reading it pretty much right...


We've got another update coming out soon (in the next hour). Tonight, I may do another live blogging session with the models... And yes- we are gradually be nearing the point that we can start to look at satellite/radar more and models less.

Posted by: Jason-CapitalWeatherGang | December 25, 2010 12:07 PM | Report abuse

I haven't any idea what the airlines/airports are capable of, but I DO know that my husband and I are stuck in DC because Delta canceled 500 flights in/out of Atlanta yesterday evening at 5:30 because of the weather that MIGHT be headed that direction. So, my family sits in Atlanta where, by all reports, it's sunny and 37, and we sit here in MD where it's cold, gray and DRY. Major overreaction by Delta this time--they blew it.

Posted by: ophelialit | December 25, 2010 12:07 PM | Report abuse

This reminds me of the Jan 25th 2000 snowstorm in that it's severity wasn't predicted until the last hour (though nobody is calling for 20" in NC with this one). Looks like this may fall into the same category, we may not know until tonight if this is a big hit or a big miss. Sweaty palms indeed!

Posted by: cloudking1 | December 25, 2010 12:08 PM | Report abuse

I hope people realize this appears to be one of those storms where its absolutely impossible for weather person, even the best, to nail down exact snowfall totals in this area. The slightest storm track deviations and location of where the storm bombs out, could be the difference between 2 or 20. Or even a situation where DC could get 4 while Baltimore/Annapolis get 14. My advice would be for everyone to expect 3 to 6, but don't be surprised if they either get a A) nothing or B) 16.

Posted by: realclear | December 25, 2010 12:10 PM | Report abuse

CWG- you by far are the best forecasters in the nation, you present your educated opinions and pass on all the info you are working with. As a VDOT plow contractor, this blog has been indispensable since i found it.
Please cont. to post the latest model info as it comes in, but please do it without taking away from ur family's christmas.
To all u asking specific travel info please keep in mind the greatest part of this blog is CWG gives us the info and leaves it to us to make our own inferments about when, where, and how much

Thanks and merry christmas
ps. to all you snow lovers- using my b-day wish today for our blizzard hopes

Posted by: vtjudyz | December 25, 2010 12:11 PM | Report abuse

Too bad can't get you a good bottle of scotch for the live blogging to keep you motivated - or demotivated. Always enjoyed y'alls take since pre-WashPo CAPX days.

Posted by: somdcommuter | December 25, 2010 12:12 PM | Report abuse

"My advice would be for everyone to expect 3 to 6, but don't be surprised if they either get a A) nothing or B) 16."

That's why I want percentages of likelihood from CWG. I will act and advise based on those. I read this and other weather sites RELIGIOUSLY, so people come to me when they want to know what's most likely to happen. The link I posted to WRAL -- those meteorologists are the North Carolina equivalent of CWG, I just need to know what it's going to be like in the DC region since I'll be driving north into that.

Posted by: AdmiralX | December 25, 2010 12:17 PM | Report abuse

This storm seems to be getting underway. My question to Jason and the rest of the gang is about the nature of this developing storm. Is the mass of precip that we see on radar the storm that will continue to grow? Or is this one of those prelim storms that will eventually transfer the energy to the coast like those storms that bomb out off the coast?

Because right now the current mass of precip seems to already be turning northward and seems within pretty good shot of our area. It also seems potent already, so I'm wondering how you guys know when this phasing happens or about when it will happen.

Thanks guys. Look forward to your continued updates.

Posted by: bbirnbau | December 25, 2010 12:24 PM | Report abuse

Thanks for working so hard on Christmas Day.

Where can we see a bigger version of the Short Range Ensemble Forecast Model you show above?


Posted by: -TBG- | December 25, 2010 12:24 PM | Report abuse

Thanks for the updates. I'll be making my travel decision based on your updates. Merry Christmas!

Posted by: mmsq | December 25, 2010 12:24 PM | Report abuse

When you begin updating and giving accumulation forecasts, us CWG readers in Hampton Roads/Williamsburg would love if you can expand the map a bit to include us, especially since we are likely to be majorly impacted by this storm. Many thanks!

Also, since it's going to be a Boxing Day storm, my vote is to call it, if it unfolds as a big one, PacquiWOW.

Posted by: orduckfan | December 25, 2010 12:27 PM | Report abuse

According to the radar there's really nothing north of Charlottesville right now. According to my eyes it's snowing in Manassas.

Posted by: TheJoeGreene | December 25, 2010 12:32 PM | Report abuse

Looks like to trip to NH will be ok as long as I stay west rather than on 95

Posted by: mandarb77 | December 25, 2010 12:32 PM | Report abuse

for all interested, here's an interesting water vapor loop, you can see the clouds starting to pull north as teh southern stream system over the south starts interacting with the northern stream. Looking at the image, it's hard to envision a complete whiff.

Posted by: wjunker | December 25, 2010 12:39 PM | Report abuse

We really appreciate you all keeping us updated even on a big holiday. It's been very helpful for folks like us who have travel plans tomorrow to have the best possible information. Thank you.

Posted by: krrolney | December 25, 2010 12:45 PM | Report abuse

I hope that everybody that welcomes this storm, if it comes, thinks for a second about those with non-refundable plane tickets this week.

Posted by: bmfc | December 25, 2010 12:47 PM | Report abuse

Where's WalterinFairfax? Someone got him wrapped in a straightjacket or something?

Posted by: waterfrontproperty | December 25, 2010 12:53 PM | Report abuse


I so hope you're right! Thank you for some perspective!

Though I must say that flying out of National during even the smallest amount of snow & remembering the 1981 crash into the 14th St. Bridge gives me pause . . .

Posted by: Post43 | December 25, 2010 1:00 PM | Report abuse

on AmericaWx blog someone says about the latest 36 sub 984 starting to get captured bout 100 miles east of ac (Atl. Cty)...hvy precip from balt to boston
Def starting to look more and more likely that there will be Winter Storm Warning snow totals northeast of here. Suppose it might be such a close call here that we won't know for a little while yet what will happen. A dusting to 5 inches here (in DC) perhaps?

Posted by: BH99 | December 25, 2010 1:05 PM | Report abuse

been following your blog for a long time and wanted to say thank you so much for keeping us informed of the weather. Kudos to WaPo for hiring you folks. It's the best gift we could get from WaPo. Also... of course, merry christmas! :)

Posted by: labyriza | December 25, 2010 1:06 PM | Report abuse

Kierein's sporting the plaid shirt today, no suit and tie for the Xmas webcast

he's got 3-6 immediate metro, 6+ east of BWI, 1-3 west of Leesburg

in NY, similar pattern, WNBC's saying 6-10 City, 10+ Eastern LI and CT, 3-6 Northwestern NJ

in Boston, WHDH's got 12+ Boston and east, 6-12 west

Posted by: TGT11 | December 25, 2010 1:07 PM | Report abuse

In short, you guys still don't know for sure. I need your job. Say anything can happen and still get paid. I'll just consult my crystal ball, it will likely be more reliable.

Posted by: concernedaboutdc | December 25, 2010 1:10 PM | Report abuse

Pay no attention to the previous poster. You folks are doing your typical outstanding job -- on Christmas Day, no less -- and I appreciate it.

Posted by: EricinReston | December 25, 2010 1:13 PM | Report abuse

Re: the criticisms: I can't imagine taking the time to post such negative comments about people working so hard on Christmas Day. Why not just log off?

I've said it before but am compelled to say it again -- thanks, CWG. The rational readers understand that weather is truly complicated and predictable only to a certain point, but appreciate all of the different perspectives/possibilities you provide.

Posted by: RASinDC | December 25, 2010 1:24 PM | Report abuse

To Eric and RAS - yep, you're right. CWS - just ignore that poster. :)

Posted by: labyriza | December 25, 2010 1:29 PM | Report abuse

As I said, it is a great job to have. When you are wrong, nobody really cares and you still get paid. Not just the CWG, but the NWS, NOAA, Weather Channel, Accuweather and local meteorologists.

I understand the city is at its highest readiness level to get the white stuff off the roads by Monday and next week promises warmer weather to melt whats left away.

If you can't tell, I just don't like heavy snow. I work and it is burdensome.

Posted by: concernedaboutdc | December 25, 2010 1:33 PM | Report abuse

concernedaboutdc i guess you are the reason for the saying "it takes all types"

Posted by: teacher11 | December 25, 2010 1:37 PM | Report abuse

There's a new post up btw.

Posted by: Murre | December 25, 2010 1:37 PM | Report abuse

It's time to start paying attention to what is actually happening on the weather map.

Looking at radar loops and hourly surface report, it seems apparent that the storm is blossoming. Already a band of moderate to heavy snow extends from NE Alabama, thru eastern Tennessse and western North Carolina. That band seems to be headed right toward DC.

It's already snowing in southern VA. I would think that the snow will start not far from midnight, light at first, heavier toward dawn.

With the flow backing and the storm rapaidly developing, it is hard to imagine that the area of heavy snow will past to our east.

So I believe that 6" in the DC area is fairly certain and that 12+ is realistic possibility if everything goes right.

That's my opinion, right or wrong.

Posted by: frontieradjust | December 25, 2010 1:54 PM | Report abuse

Thank you so much for the diligence on the storm this week. I have learned more here about winter storms than in 30 years elsewhere as a weather nut.

Feels like a good storm brewing in the country, the birds were out and about earlier, but now it is getting still outside. Like another present yet to come. Checking the plow and gas, shortly.

Posted by: Gooddogs | December 25, 2010 2:22 PM | Report abuse

If this thing produces anything substantial, the storm should aptly be named "SnoWhat!?" due to the unpredictable forecast.

Posted by: PoorTeacher | December 25, 2010 2:49 PM | Report abuse

Posted by: wjunker | December 25, 2010 2:54 PM | Report abuse

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