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Posted at 10:15 AM ET, 01/25/2010

Late-week snow potential emerging

By Jason Samenow

* Turning more wintry: Full Forecast | A snowy surprise 10 years ago *

Next Chance of Accumulating Snow: Thursday night through early Saturday
Probability of Accumulating Snow (1" or more): 40%
Most Likely Potential Impact:

As an Arctic front drops south through the region late Thursday night, there is a decent chance some snow will break out. In some places (mainly east of I-95), precipitation may begin as rain or a mix, but cold air pouring into the region should change everyone to snow, for at least a brief time.

Low pressure will develop along this front and may pass to the south of the metro region. This could mean the heaviest snow falls in central Virginia (and possibly to the south and southwest) before the storm passes out to sea. However, there is a possibility that the storm will track further north and turn up the coast. In this scenario, heavier precipitation would work its way into the metro area, and last for a longer period of time. There's also the outside chance a track closer to the coast would cause some warmer air to work its way into the metro area, increasing the chance of some mixed precipitation.

Here are the current accumulation possibilities which will certainly evolve in the next several days:

30% chance: A dusting or less
30% chance: A dusting to 1"
20% chance: 1-5"
20% chance: 5"+

Stay tuned for more updates each day.

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

By Jason Samenow  | January 25, 2010; 10:15 AM ET
Categories:  Snow Lover's Crystal Ball  
Save & Share:  Send E-mail   Facebook   Twitter   Digg   Yahoo Buzz   StumbleUpon   Technorati   Google Buzz   Previous: Forecast: Strong winds and showers this morning
Next: A snowy surprise, 10 years ago today


Hmmm - my guesscast from taking a look at the models is accurate at this point.

Posted by: stinkerflat1 | January 25, 2010 10:29 AM | Report abuse

We are driving south wednesday to Ft Lauderdale Fl for a cruise. We were going to leave thursday, but we want to get s of the storm

Posted by: pvogel88 | January 25, 2010 10:49 AM | Report abuse

I was just wondering where the SLCB was... ;)

Posted by: hobbes9 | January 25, 2010 10:58 AM | Report abuse


Posted by: CapitalClimate | January 25, 2010 11:03 AM | Report abuse

Have fun on your cruise! They are so much fun.

Posted by: PeterBethesda | January 25, 2010 11:11 AM | Report abuse

SLCB at 72+ hours? Cap Wx, I sense you are holding some of your cards, no? I thought I was done with snow when we got a year's supply last month, but I feel the snow excitement ramping up against my better judgement.

As a side note, I have buds on my trees!

Posted by: chrissie413 | January 25, 2010 11:17 AM | Report abuse

Sorry, but I may have to side with ThinkSpring and the other warm-weather advocates on this one.

This storm impacts the Jan. 29 VIP singles dance plus two swing dances also scheduled for Friday night. It's likely though that if the storm is big the dances will be cancelled or postponed. The big issue is whether the Friday PM rush hour and Friday night road conditions are impacted.

I have already e-mailed the folks in charge of both dances.

Posted by: Bombo47jea | January 25, 2010 11:42 AM | Report abuse

From NWS Hydrometeorological Prediction Center:



Posted by: CapitalWeatherGang | January 25, 2010 12:01 PM | Report abuse

Could you please interpret that last forecast comment CWG?? Thanks!

Posted by: someonelikeyou | January 25, 2010 12:18 PM | Report abuse

Today is close to 60 degrees and I am contemplating a snowstorm on the weekend!

Love it!!

Posted by: celestun100 | January 25, 2010 12:20 PM | Report abuse

I'd be disappointed if we only had one major snow event this winter. You need at least three to make it an official winter.

So my wishcast is 4-6" on Thursday, and then another 10-12" on Friday as the storm sits off to our southeast and doesn't move for a while. No school for the kiddies on Friday, and early dismissal on Fri for los federales.

I now return you to rational, fact-based analysis.

Posted by: 20009matt | January 25, 2010 12:24 PM | Report abuse


In plain English...

The National Weather Service sees potential for a significant winter storm extending to the mid-Atlantic states late this week.

Posted by: CapitalWeatherGang | January 25, 2010 12:25 PM | Report abuse

Lovin' it today! Shorts on and waitin' for some more snow beginnin' Friday ( I believe) and ending Sun mornin'! Thursday seems a bit premature as this thing stalls a bit in Tennvall/SApps on Thursday afternoon...Gotta love the Mid Atlantic region! GO TERPS!!

Posted by: GMorg11 | January 25, 2010 12:25 PM | Report abuse


Sounds great, but I have a feeling that wishcasting doesn't work!!! Too bad because I love the "sits off to our southeast and doesn't move for awhile" idea!!!

Posted by: celestun100 | January 25, 2010 12:27 PM | Report abuse

I'm really torn on this one...I would love another storm, but this is a particularly busy time for a lot of feds (like me) so I'm not excited at the prospect of having to drive in a major storm. But I can't turn off the 10 year old part of myself that is doing a happy snow dance right now!

Posted by: bachaney | January 25, 2010 12:34 PM | Report abuse

Hey CWG - any records set with this ridiculous non-tropical 990mb Low sitting off to our west? My ears are actually popping from this low pressure, and I was surprised to see Dr. Masters on WXUnderground mention that this storm set all kinds of lowest pressure records out in CA and AZ...

Posted by: DullesARC | January 25, 2010 12:51 PM | Report abuse

Insightful analysis, as always, from Capital Climate. Me thinks there may be a little bitterness at not being part of the team anymore?

By definition, a post that is titled "Late-week Snow *POTENTIAL EMERGING*" cannot be hype. Nor can an analysis that gives just a dusting to 1 inch a 60 percent (more than half, in case you need help) probability of occuring.

Go away - you ruin the interactivity of this site for everyone else.

Posted by: SouthsideFFX | January 25, 2010 12:51 PM | Report abuse

Yep - MadMan Margusity see this as a 6 inches to a foot+ storm for the region. Looks to be (at this point) that we are in the bullseye here in the DC-Balto region! I'll take a foot!

Posted by: stinkerflat1 | January 25, 2010 12:57 PM | Report abuse

Joe Bastardi (Accuweather) predicts a cold and snowy February for the eastern half of the country. I really hope so. I could use a few snow days.
I'm going to give a few gifts to the snow Gods Wednesday and Thursday night to make sure that we get a storm and maybe Friday off.
Really hoping that mid Feb will look like mid December.

Posted by: Bainbridge | January 25, 2010 1:19 PM | Report abuse

"bull's eye"!?!?!


Posted by: walter-in-fallschurch | January 25, 2010 2:16 PM | Report abuse

Well, if this happens it could be fun! I'm not getting my hopes up yet though.

Posted by: kallieh | January 25, 2010 2:30 PM | Report abuse

... though as someone just pointed out in Accuweather's forums, for this to miss us completely and not give us something it would essentially just have to go off coast in GA which would require a lot of factors going wrong from the model runs.

Posted by: kallieh | January 25, 2010 2:39 PM | Report abuse

Your accumulation potentials seem way too low, considering many of current models suggest at least 8 inches for the city (one foot plus in central Virginia).. This is why I have a problem with your percentages.. They allow you to hedge your bets too much. In effect, you just said it will snow, but we have no idea how much and no matter what we say, we will be right.

Posted by: realclear | January 25, 2010 2:53 PM | Report abuse


Can someone post a link to this? I've searched around and cannot find this mentioned anywhere except on the capitalweathergang site.
This page doesn't mention it:

Posted by: spammy2 | January 25, 2010 3:06 PM | Report abuse


We're highlighting the possibilities at this point as it is way too soon to be making a definitive call. It's true that the overall pattern looks favorable and some (but importantly, not all) models are simulating some good snows. Models are seldom correct in this time frame. Often, when they represent substantial snow 96 or more hours out they fail miserably. Any experienced forecaster knows our state of knowledge and model skill are insufficient for making a responsible forecast at this point.

Bottom line-- this post is serving as a "heads-up" to the potential. We're not trying to be right or wrong here. We'll provide narrower ranges and a more deterministic forecast as we get closer to the event.

Posted by: CapitalWeatherGang | January 25, 2010 3:16 PM | Report abuse

Posted by: CapitalWeatherGang | January 25, 2010 3:21 PM | Report abuse

Posted by: skywatcher1 | January 25, 2010 3:23 PM | Report abuse

I don't want to argue, but last week you had a forecast that said something like 30 percent chance of 2 to 5 and 20 percent chance of 5 plus and then 20 percent chance of less than 1.. Well, we got nothing... Is that forecast not wrong, since you called for a 50 percent change of at least 2 inches. Or are you right cause you had a 20 percent chance of less than 1 verified??

All I am saying is its easy to do the weather when you can give such big ranges. I respect your work and like your blog, but people would never allow the television weathermen to do what you all do...

In my book, if we get more than 5 inches later this week, you all will have been miserably wrong cause you under played the potential. Last week, you were miserably wrong cause you overplayed the potential... Isn't it better to give no range at all if you are not sure??

Posted by: realclear | January 25, 2010 3:23 PM | Report abuse

I pooh-poohed Accuweather's prediction of the mother of all snowstorms the Monday before we got hammed in mid-December. So I'm just going to shut my mouth now.

Posted by: ValleyCaps | January 25, 2010 3:28 PM | Report abuse

At 96 hrs out the bull's eye is not where we want to be. The bull's eye has a tendency to move northward as the event gets nearer. With the Snowpocalypse in December, the models were calling for the bull's eye to be in the Richmond area until we were well within 48 hrs of the storm.

Posted by: bdeco | January 25, 2010 3:29 PM | Report abuse

bdeco. if you look at the models the bullseye for this storm is also currently in Richmond.. (one model has richmond getting about 16 inches while DC gets about 8)

Posted by: realclear | January 25, 2010 3:34 PM | Report abuse


You are referring to the one post last week where we made a mistake and overdid the odds of accumulating snow. We quickly backed away from that forecast. After that one post, we then said less than 50/50 chance of an inch in DC and ultimately called for less than inch in all of our forecasts within 24 hours of the event.

This is a not a TV station and the local TV broadcasters rarely, if ever, mention accumulations until within 24-36 hours. We're trying to give folks some idea of the possibilities before you'll get this information on TV. Sure, you might get a Joe Bastardi or Henry Margusity from AccuWeather talking specific accumulations days in advance, but they get burned more often than they are right IMO - because the science is not there.

What we try to do is identify potential, indicate the possibilities (we usually err on the side of being conservative to start with, because so many things in DC have to come together for it to snow), and then, when our confidence is sufficiently high, provide our best estimate of the actual accumulation total. We usually beat the TV stations on getting our first accumulation map out.

Agree that it's hard to be wrong when you give probabilities, but we're giving you those when nobody else is AND we're giving you our best bet as soon as feel the science justifies it.

Posted by: CapitalWeatherGang | January 25, 2010 3:38 PM | Report abuse

@ real clear

That's exactly where we want it to be right now!

Posted by: bdeco | January 25, 2010 3:39 PM | Report abuse

It's entirely appropriate to stick with probabilities, trends and confidence levels from 4-5 days out. Way too early to figure out a bull's eye for this, or any other storm. I like the CWG's treatment of "potential" events very much. You can leave the wishcasting to us, your somewhat disturbed commentors.

Posted by: curtmccormick | January 25, 2010 3:43 PM | Report abuse


"Isn't it better to give no range at all if you are not sure??"

Uh, then there would never be any weather forecast, ever, since you can never be "sure".

I think the CWG entry about the surprise snowstorm of 2000 pretty persuasively illustrates that giving % likelihoods is a far superior method of forecasting than the deterministic method you advocate.

Posted by: ryanem1 | January 25, 2010 3:46 PM | Report abuse

I understand CWG. And, as I said earlier, I respect what you all do.. My only point is that you can be wrong by underplaying a storm just as much as folk can be wrong overplaying a storm threat.. But as of now, I will take you at word that there is a 60 percent chance that DC will get one inch or less of snow later this week

Posted by: realclear | January 25, 2010 4:18 PM | Report abuse has up high percentages for snow thurs night, friday, and saturday for my zip code. They are usually the last ones, by far, to put up possibilities so I'll take that as a good sign. But then they have our temps being marginally on the too high side- potentially reaching into sleet or freezing rain territory. I'll take that as a bad sign.

I end up neutral. Yes, I realize that compared to people who read models and all that my way is incredibly unscientific. :-P

Posted by: kallieh | January 25, 2010 4:22 PM | Report abuse


I agree that you can be equally wrong in both directions (underplaying and overplaying a storm). Generally speaking, I think most people understand that there is a ton of uncertainty to accumulation probabilities more than a couple days in advance of a storm. And that nothing is set in stone until a more deterministic forecast is provided closer to the event (and even then we know things don't always pan out as predicted). But that doesn't mean there isn't any value in providing probabilities early on. We have the ability here to go above and beyond what the TV folks do with in-depth items like the Snow Lover's Crystal Ball, while at the same time we're providing the more basic forecast information in our regular forecast posts. Part of the fun of the Crystal Ball, in my opinion, is taking the probabilities for what they're worth and watching how the forecast and probabilities evolve over time.

Posted by: Dan-CapitalWeatherGang | January 25, 2010 4:54 PM | Report abuse

I love the snow and always miss the good storms. Storm of '96, out of town. Storm of 2003, out of town. I will be out of town for the weekend, so that means the chances of a big snowstorm hitting just went up significantly. Lucky local snowlovers!

Posted by: winterchic | January 25, 2010 5:04 PM | Report abuse

Question: You note above that models are "seldom correct" in this time frame. Do you have a dfinition of "correct" here? Otherwise you're sort of implying that the models are negative indicators: that snow in the model now indicates an increasing chance of there being no snow.

Posted by: oldtimehockey | January 25, 2010 5:21 PM | Report abuse

As soon as you explain how your undisclosed conflict-of-interest, i.e., working for an energy-industry lobbying organization, contributes to your "incisive analysis" of climate policy, we can have that conversation.

Conveying the information without hysteria (from NWS):

Posted by: CapitalClimate | January 25, 2010 5:34 PM | Report abuse


They're seldom correct in the exact details though they usually have the big picture pretty close to right. But because so many ingredients need to come together just right for significant snow here, getting a detail or two wrong can have big implications.

Posted by: CapitalWeatherGang | January 25, 2010 5:40 PM | Report abuse

The problem I have with overrelying on probabilities is that there is no forecast when you cover every possibility, unless you assume anything with over a 50% chance is the "forecast." Under that scenario, CWG currently predicts an inch or less of snow with this storm, and anything more would not have been predicted at this time. As for the "Crystal Ball" - that would be great if you identified storm chances a week or more out. Even the NWS discussion this past Sat morning already mentioned a possible southern storm at the end of the week. For several days there have been comments here like "what about the end of week storm chances?" - so raising the possibility on Monday of an event Thursday night isn't exactly getting out ahead of other outlets. I think the value CWG brings is in deeper analysis of the forecast variables, updated coverage of storm events while they are happening, and retrospective analysis.

Posted by: manatt | January 25, 2010 6:21 PM | Report abuse

Hmmm.... I'm usually the first one to welcome snow - I love it. However, this weekend my mother-in-law has offered to watch my four horrible children and give my hubby and I a much-needed overnight away. If there's so much as a flake in the sky or the talk of snow, there is no way she's making the 17 minute trip around the beltway from her place to ours. My forecast for the weekend? Chance of romance and indulgence looks cloudy. Frigid air may affect husband as weekend away disappears leaving accumulations of stress.

Posted by: someonelikeyou | January 25, 2010 6:49 PM | Report abuse

you should work out your inferiority complex before posting

Posted by: Peter_L_inmclean | January 25, 2010 7:09 PM | Report abuse

1" - 10"...

I have never seen the SLCB posted this far in advance ( 84+ hours) of a potential storm. Is this "hyping" or is this " highlighting the possibilities"? Only time, and the CWG, will tell.

I happen to trust the CWG and believe they are seeing something to warrant the posting of the SLCB, no matter the possible percentages of a trace to "12inches+" of snow.

There is some good agreement in the models of the overall picture of the weather pattern for the near future. Most models agree that a low pressure system will develop in the southern stream near the Mexico/Texas border. This storm is prognosticated to tap the moisture from the Gulf of Mexico and move northeast towards the mid-Atlantic coast. This is where the uncertainty of the forecast comes into play. How far will a cold front sag to the south of DC? Does the low pressure system move up the coast or out to sea? When does the low pressure system re-develop off the coast?

Apparently the CWG - and the NWS - believe there is enough of a chance that this storm will give us some accumulating snow to warrant the SLCB a full 84 hours (or more) in advance of this "potential" storm. I personally am hoping for a good storm. The December 19 storm was great but it was early and I am now ready for the next round of winter. 68 degrees was nice and a well deserved teaser of spring. But face it folks... it is still January. Let's enjoy winter until it is Spring.

Posted by: pjdunn1 | January 25, 2010 7:49 PM | Report abuse

I for one appreciate the Snow Lover's Crystal Ball and think the discussions it spawns are great fun to read! Please keep up the good work CWG!

Maybe it could have been warranted on Sunday - but hey - its here now, so enjoy it.

As for the percentages, I always saw the range offered as being pretty helpful in better understanding the confidence in the current models as opposed to being a prognostication on what the actual event will dump - at least when more than 48 hours out.

As a lawyer, I recommend a disclaimer!

As a reader, I say again, great job and keep up the good work!

Also noticed the change in weather icons - no snow for Thursday during the day, and Friday's precip % increased to 40, with an extra snowflake floating from the cloud. All positive signs IMO!

Posted by: hrc2211 | January 25, 2010 7:57 PM | Report abuse

I LOVE the Crystal Ball, LOVE the prognostication, and LOVE CWG for being the place to discuss the possibilities. I appreciate and value the CWG's opinions and analysis, and I don't expect 100% accuracy (although I do trust them!). I enjoy this site precisely because it goes beyond what the TV forecasters are willing to say. The fun part for me is seeing what may a snow lover, I like it when I can have a little hope! Thanks, CWG - keep up the good work!!

Posted by: kathyb39 | January 25, 2010 8:47 PM | Report abuse

"Capital Climate," I don't think I was commenting on climate policy, was I? And have I in, I don't know, over a year? And since you seem to know so much about me, why the need for "disclosure?"

Oh, and, bitter much?

Posted by: SouthsideFFX | January 25, 2010 8:50 PM | Report abuse

I believe the SLCB was posted because of the consistent model agreement over 3+ runs to the possibility of a storm. Usually 4/5 days out there is still a lot of uncertainty to the track and intensity of the storm. This time around, there was great agreement on those issues. Anyways, by definition, the SLCB is issued more than 2 days out.

I have no idea what all this hubbub is about. Its been posted dozens of times before without all these questions.

I guess the masses are restless for snow.

Posted by: jpl1019 | January 25, 2010 9:42 PM | Report abuse

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