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Posted at 12:43 PM ET, 12/24/2010

Weekend snow threat still slight

By Jason Samenow

It's tempting to throw in the towel for the prospects of meaningful snow this weekend, but we're holding off. Enough uncertainty remains with respect to how this storm will evolve that we can't yet entirely rule out some snow for the metro region.

Wes Junker, our winter weather expert, says: "Any snow on Christmas day would be mostly flurries. But there remains a low end chance of light to moderate snow on Sunday due to a lot of uncertainty in the storm track."

If you have travel plans taking you into southern New England, you should keep a very watchful eye on the forecast. Wes cautions: "Most of the computer models bring the storm close enough to New England where there is the potential for a pretty big snowstorm."

Next accumulating snow chance: Mostly Sunday
Probability of accumulating snow (1" or more): 30%
Probability of more than 4": 15%

Keep reading for the technical discussion...

TECHNICAL DISCUSSION

Christmas snow: If we were to get any snow on Christmas day, it would be from the disturbance diving southeast along the northern jet stream. However, all the models show any precipitation associated with this feature drying out as it crosses the mountains and there's no moist flow from the south (warm air advection) to generate the lift necessary for much snow to develop. So the most snow we would expect to see on Christmas day would be some conversational flurries.

Sunday snow: All model guidance this morning suggests the coastal storm that develops Sunday passes far enough east that we get no snow with the exception of the GFS model (and the Japanese model, which we seldom use and has a bias tracking storms too close to the coast). The GFS model, taken literally, would indicate up to 1 to 3 inches. However, NOAA indicated there was an initialization problem with the model this morning, and thus:

THE SPECIFIC PREDICTIONS ... ARE IN QUESTION. . . . . [WE DISREGARD] THE SUBSTANTIALLY DEEPER AND WESTWARD SHIFT OF THE 12Z GFS REGARDING THE POWERFUL LOW TRACKING UP THE EASTERN SEABOARD.

So while the GFS model would give snow lovers a little hope, it doesn't appear like its output is credible.

Nonetheless, a few ensemble members of the various models track the low close enough to the mid-Atlantic coast to keep a small possibility of snow Sunday in the forecast.

As long as there is a chance, we'll keep providing updates. Look for the next one (brief) late tonight (around 11 p.m.).

By Jason Samenow  | December 24, 2010; 12:43 PM ET
Categories:  Latest, Snow Lover's Crystal Ball, Winter Storms  
Save & Share:  Send E-mail   Facebook   Twitter   Digg   Yahoo Buzz   Del.icio.us   StumbleUpon   Technorati   Google Buzz   Previous: A look back at big Christmas snows in D.C.
Next: Update: Bumping up Sunday snow odds

Comments

12z GFS and JMA both bring precip further west into our area between 48 and 72 hours. The ECMWF takes the precip east. But isn't it true that the ECMWF is more accurate in long range forecast and that the GFS tends to be more reliable in the short range? NWS is citing errors in the 12Z GFS run, so the 18Z run will be very interesting.

Posted by: DLO1975 | December 24, 2010 1:46 PM | Report abuse

Jason, just want to thank you and the CWG team for the excellent coverage of this event.


Posted by: TGT11 | December 24, 2010 1:48 PM | Report abuse

was just checking out a Connecticut site, and they're expecting to just get "brushed"

Posted by: TGT11 | December 24, 2010 1:50 PM | Report abuse

Justin Berk just posted new thoughts...

On a conference call with Richard Muth, MEMA, along with others. This is about the weekend storm which looks like it is taking form for Maryland. I want to thank them for trusting my insight. Here are the basic thoughts...

Saturday: Light snow mid morning to early afternoon.
Sunday: Snow arrives in Salisbury/Ocean City after midnight- but goes all day. Chance of 6-10"+ is 70%
Baltimore chance of 4"+ Sunday afternoon through Monday morning.
3 minutes ago

Posted by: DLO1975 | December 24, 2010 1:51 PM | Report abuse

DLO1975, verification of precipitation forecasts by HPC of both the Euro and GFS indicate that on average, the euro mdoel precipitation forecasts are superior inside of 72 and 48 hrs. I guess I'm saying that your perceptions are not correct.

Posted by: wjunker | December 24, 2010 2:08 PM | Report abuse

DLO1975, the Euro is usually very solid in this range. I'd personally expect it to be closer to right than the recent GFS. Sunny and calm here in CT... Wouldn't mind some snow but not getting hopes up too much yet.

Posted by: Ian-CapitalWeatherGang | December 24, 2010 2:10 PM | Report abuse

Call it wishful thinking, but I think the storm is going to track closer to the coast and we are going to be pleasantly surprised with a 4-8" snowfall on Sunday....

Posted by: snowlover | December 24, 2010 2:59 PM | Report abuse

I don't know.

The GFS is really backing the 500 mb flow, showing good surface inflow, taking an upper low south of us, super large and powerful 850 mb upper low. If the GFS depiction is correct, the precip printout is probably underdone.

This situation still has some favorable aspects. The models have been all over the board (thus useless) and we still don't know the final solution with respect to this potentially significant winter storm.

Posted by: frontieradjust | December 24, 2010 3:01 PM | Report abuse

I'm admittedly no expert (former meteorology major that follows the weather as a hobby), but have tried to learn as much as possible from the accuweather pro and other sites over the years. I know that Bastardi and others have mentioned on more than one occassion that the Euro model is one of the best long range forecasters...and I also know there's a lot of reliance on the GFS when it comes to short range forecasts. There are two models now (GFS and JMA) bringing precip further west. I'm just saying this could get interesting. Given that I fired up the snowblower today to ensure it was working, I'm sure this will be a miss.

Posted by: DLO1975 | December 24, 2010 3:08 PM | Report abuse

snowlover - we shall see! I will check back with you next week to see if your prediction verifies :)

Posted by: Camden-CapitalWeatherGang | December 24, 2010 3:14 PM | Report abuse

Want to thank everyone for weighing-in. Always appreciate the discussions we can have on the comment board here at CWG. This is a very tricky scenario. Models are exceptionally inconsistent, so there is MUCH to interpret. But all in all, chances for snow are decreasing, along with potential amounts; however, we aren't writing it off yet. Hope to check in here with you all tomorrow and the CWG and I can have higher confidence as to what will transpire Sunday/Monday. Take care, all!

Posted by: Camden-CapitalWeatherGang | December 24, 2010 3:17 PM | Report abuse

18Z NAM has shifted even further west.

Posted by: 4seams | December 24, 2010 3:22 PM | Report abuse

for any folks relying on the 12z GFS...I think the guidance was essentially "ignore it" since it initialized with some bad data.

my favorite snow was the one 2 weeks ago where we got that lake effect snow spike right through here and 1/2" or so as a fun surprise.

Posted by: AndrewRockville | December 24, 2010 3:25 PM | Report abuse

LWX didn't mention snow on Sunday in the 12pm forecast, but they've just added it back in at 3pm:

http://weather.noaa.gov/pub/data/forecasts/zone/va/vaz053.txt

Posted by: oriolesfan2323 | December 24, 2010 3:34 PM | Report abuse

18z NAM is nothing like the 12z GFS was. Still looks like maybe an inch... maybe on the 18z NAM.

Posted by: KRUZ | December 24, 2010 3:35 PM | Report abuse

The 18Z nam is a miss for here but a big hit for new england. The 15Z sref gives dca a 30-50 percent chance of 0.10 liquid (an inch or so of snow) but it shows lots of uncertainty about the track and I'm not sure what the impact of any problems that might be inherent in the GFS would impact them. Still lost fo uncertainty. I'd be really surprised by a major hit but not by a minor one. The nam pretty much dry slots us.

Andy, I glad to see you posting.

Posted by: wjunker | December 24, 2010 4:07 PM | Report abuse

Excuse all the typos in the last post. Andy good to see you are posting. and there still is lots of uncertainty as indicated by the 15Z sref runs.

Posted by: wjunker | December 24, 2010 4:09 PM | Report abuse

Refusing to be teased back into any kind of hopefulness.
Surprise me Santa...PLEASE.

Posted by: FIREDRAGON47 | December 24, 2010 4:29 PM | Report abuse

It seems as the storm gets closer the GFS and the sref are pushing it more westward. New GFS models coming in now..

Posted by: MVPlaya8120 | December 24, 2010 4:41 PM | Report abuse

the latest from Channel 7 in Boston

How much snow will fall? That's the million dollar question right now. If the dynamics set up just right and the timing of phasing of storms is spot on, then we could see 6-12 inches of snow...mainly across southeastern MA. If those dynamics don't work out perfectly, then we're looking at about 2-5 inches of snow in that timeframe.

http://www1.whdh.com/weather/blog/page/1/

Posted by: TGT11 | December 24, 2010 4:49 PM | Report abuse

Guys,any comment on the 18z GFS?

Posted by: snowlover | December 24, 2010 5:01 PM | Report abuse

18z GFS is coming in now. The track is definitely a minor hit for DC and the eastern suburbs but is showing the eastern shore as a major hit. Is this just a continuation of an initializing error as per the 12z run? Interesting to see how this plays out over the next 24 hours.

Posted by: pjdunn1 | December 24, 2010 5:03 PM | Report abuse

Hmmmm...Maybe I maybe misreading this but the GFS 18Z is still throwing a bit of ppn the DC area way...Not sure the GFS 12Z data issues can explain the fact that GFS is sticking to it is guns here regarding snow potential...or so I think

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfsp03/18/images/gfs_p03_054m.gif

Posted by: BigHH | December 24, 2010 5:05 PM | Report abuse

It seems like the 18z GFS tracks it even farther west than the 12z....This could get interesting.

Posted by: MVPlaya8120 | December 24, 2010 5:07 PM | Report abuse

A little further -- The 18z GFS gives Baltimore 6-10" of snow....

Posted by: snowlover | December 24, 2010 5:12 PM | Report abuse

Im gonna throw in the towel for this snow. Crowds at grocery were a lot less today than yesterday. The Mob has voted... no big snow. Remember.. there is a lot of time left this winter for a snowstorm!

Posted by: pvogel88 | December 24, 2010 5:13 PM | Report abuse

hpc is throwing out these runs since models do not agree. What is going on? Late night run should be looked at carefully. This will create nightmare putting forecast with less than 24 hrs of incoming storm if these latest runs agree. What do u all think??

Posted by: chetupadhyay | December 24, 2010 5:30 PM | Report abuse

Is the GFS is really calling for an explosive, 960mb low to develop off New England? Insane.

Posted by: marklandterrapins | December 24, 2010 5:30 PM | Report abuse

I'm convinced that there is some employee in Camp Springs that's upset he/she has to work on christmas and is manually swinging the models back and forth just to watch people like us go insane. 18z is no snowmeggeddon, but it's a hit. Still skeptical though...

Posted by: Brian-CapitalWeatherGang | December 24, 2010 5:35 PM | Report abuse

I'm convinced that there is some employee in Camp Springs that's upset he/she has to work on christmas and is manually swinging the models back and forth just to watch people like us go insane. 18z is no snowmeggeddon, but it's a hit. Still skeptical though...

Posted by: Brian-CapitalWeatherGang | December 24, 2010 5:35 PM | Report abuse

Hope the CWH will get to the bottom of the 18Z GFS run. Was this another error or is the GFS onto something?....

Also where does the EURO stand in all this right now?

Posted by: KRUZ | December 24, 2010 5:39 PM | Report abuse

The next GFS run should be interesting. Will it keep west going on what the Euro had for us earlier this week? Or start to push back east again? Hmmmmmmmm

Posted by: MVPlaya8120 | December 24, 2010 5:46 PM | Report abuse

The next GFS run should be interesting. Will it keep west going on what the Euro had for us earlier this week? Or start to push back east again? Hmmmmmmmm

Posted by: MVPlaya8120 | December 24, 2010 5:46 PM | Report abuse

well..wes did say earlier that he wouldn't be surprised if we got a minor accumulation. Guess that's still looking pretty possible. Perhaps and inch or two??

Posted by: BH99 | December 24, 2010 5:51 PM | Report abuse

I would think that the 500 mb solution as depicted by both the 18Z GFS and 0Z NAM would have to be way off for us to get no snow.

When you back the flow that much against a good thickness ribbon, how do you not snow? A 528 thickness is a little lower than you want, but not outrageous.

The dry pocket created by the NAM over us seems insane, but we shall see.

Posted by: frontieradjust | December 24, 2010 10:52 PM | Report abuse

What a ride...alarms please???

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

The comments to this entry are closed.

 
 
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