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Posted at 1:30 PM ET, 01/ 7/2011

Tuesday snow risk increases

By Wes Junker

The Snow Lover's Crystal Ball reappears as the chance for accumulating snow Tuesday is increasing (relative to yesterday). The models have converged toward a solution that would give the Washington area at least some snow. Therefore, the Crystal Ball assessment for the probability of getting over an inch of snow is in the 40 to 50% range, a high number given that the storm is not expected until Tuesday.

Next accumulating snow chance: Tuesday
Probability of accumulating snow (1" or more): 40-50%
Probability of more than 4": 15-20%

Yesterday Jason and Dan noted that this threat was like other storms this year and might keep us on edge because of uncertainty in the track. The two options offered yesterday are still on the table: 1) a track across the Gulf of Mexico and then off the Southeast coast and out to sea, 2) a track far enough north to produce snow for the area.

The odds of getting the latter has increased during the past 24 hours as the majority of the weather models from the various centers are now simulating snow across the metro region. The storm is certainly one worth monitoring closely over the next several days.

TECHNICAL DISCUSSION

Why have the odds for snow risen? The upper level pattern forecast on all the models looks much more conducive to getting precipitation across our area even if the surface low were to scoot out to sea.

wes-500.jpg
Last night's 1 a.m. GFS 500mb (18,000 feet) heights (pressure), wind and vorticity (atmospheric spin) forecast valid 1 p.m. Tuesday.

Note, on the forecast to the right (from the GFS model run at 1 a.m. last night) of the flow at around 18,000 feet (500 mb) that a shortwave ridge (red line) has developed over Ontario in advance of the approaching vorticity maximum (i.e. upper level disturbance) over central Kentucky and that the black lines above it separate (or spread apart) as they approach the ridge. Meteorologists call that diffluent flow which can lead to lift in the atmosphere supportive of precipitation. The map also shows the left exit region of a jet streak (fast flow in the atmosphere) approaching which also is favorable for lifting and precipitation. All of this should aid in the development of low pressure along the coast.

Where that development occurs and how far north the low tracks prior to shifting out to sea will determine how much snow we get. The system is quite progressive (i.e. moving along quickly) suggesting that the snowstorm probably will not be a mega-storm but still could produce our most significant storm of the season so far.

The GFS based on data from 1 a.m. last night gave us around 3 or 4 inches of snow despite a less than optimal track. Both the 7 p.m. GFS and European models forecast similar amounts though the latter would probably be more in the 2 to 3 inch range. The 7 a.m. GFS from this morning cut back slightly on precipitation showing a forecast that would produce 2 or 3 inches of snow as its upper level (500 mb) trough (dip in the jet stream) was not quite as strong as last night's model version. The latest Euro run from today continues to suggest a light snow event, probably on the order of a couple inches.

The ensemble forecasts from both models last night were even more favorable for snow, especially last night's late (1 a.m.) GFS run. Recall that ensemble forecasts are runs of a given model with the same physics, lower resolution and tweaks to the model's starting data (or initialization)

ensemble-tracks.jpg
Track of low pressure system from the GFS model (red) and its ensemble members (blue) from last night's 1 a.m. run

For last night's 1 a.m. GFS run shown above, the ensemble members (blue dots and lines) tended to track the storm farther west (closer to the coast, producing more snow for us) compared to the operational run (the red dots and track). And that remains the case with the latest GFS run and its ensembles. For snow lovers, that's good news. However, the ensembles were also snowy for the December 26 storm - so caveat emptor, buyer beware.

If someone put a gun to my head and said will I see snowflakes Tuesday, yes or no, I'd say yes. But today I'm feeling lucky more than skillful. The odds don't favor this being a major storm like the ones we saw last year despite the high ensemble mean forecast precipitation amounts. This looks more like a 0-6 inch storm with the most likely amounts being somewhere in the middle of the range. As you can see from the ensemble above, the spread in the track of the low grows once the low gets to North Carolina so there remains much uncertainty. And my yes or no guess is just that, a guess.

By Wes Junker  | January 7, 2011; 1:30 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: Dusting to 1" possible Saturday morning
Next: Winter weather advisory N and E of D.C.

Comments

and so it begins...

Have to admit, that even with the outcomes not being what I've wanted this winter, it's been a fun ride with the forecasting..

Posted by: Snowlover2 | January 7, 2011 1:45 PM | Report abuse

With the GFS 1AM model (red) being so far out to see and still projecting 3-4", it must have a pretty large area of precipitation, no?

Posted by: finger11 | January 7, 2011 1:52 PM | Report abuse

finger11, it's really not a huge precip shield by the time we get it. Much of precipitation is due to the dynamics associated with the upper system that is coming east. It's pretty vigorous and has a nice jet streak with it to supply lifting across our area resulting in the precipitation.

Posted by: wjunker | January 7, 2011 1:57 PM | Report abuse

Wes,
Well done and said.

After a quick glance at the 12z data, my thoughts were, probably a regional average of 1-4", unless model interpolation changes prior to the event. This concurs quite nicely with your thoughts of probably somewhere in the middle of 0-6....

Posted by: AugustaJim | January 7, 2011 2:01 PM | Report abuse

Weather board chatter is talking up a 2" to 5" event...must be the Tuesday storm.

Tuesday evening is first Clarendon Ballroom swing dance of the new year...Clarendon Ballroom does NOT like to cancel events, but attendance can be way down if snow or ice shows up.

As for a big event, that vorticity chart looks too darned zonal for my tastes...the storm will likely scoot right through here, drop a quick couple of inches [if we're lucky!] and rush out to sea. I'd really rather see an intense counterclockwise rotating, but slow-moving vorticity lobe. Not enough spin here to suit me!

Posted by: Bombo47jea | January 7, 2011 2:02 PM | Report abuse

Nothing against CWG or the good folks who post here, but I am reminded of the movie North Dallas Forty, when Mac Davis and Nick Nolte are at a party. Davis asks Nolte to go get in the "pile." Nolte says, no, it's the same of old pile (of hanger ons, drunk players, etc)

Davis laughs and says, Yea, and I'm going to go get knee deep in it.

Posted by: jaybird926 | January 7, 2011 2:11 PM | Report abuse

Bombo47jea, I agree with you about the 500, it's strung out too much for a big storm. I don't think it likely to be a complete miss but it is not likely to be a big storm.

Posted by: wjunker | January 7, 2011 2:13 PM | Report abuse

I will start hyperventilating over this pie-in-the-sky snow event on Monday & not a day sooner.
Y'all go ahead & lose sleep over it. Not me.

Posted by: FIREDRAGON47 | January 7, 2011 2:27 PM | Report abuse

Thanks for the insight jaybird926. Welcome to the club!

Posted by: HappyWeagle | January 7, 2011 2:44 PM | Report abuse

I have my broomstick ready to use in case of any dusting in our area.lol

Posted by: BlackHill | January 7, 2011 2:45 PM | Report abuse

No losing sleep here...there's a 50-60% chance of NO accumulation...those are high odds of no snow. I'll keep watching but we all know the trend by now and most of us probably expect little or nothing.

Posted by: parksndc | January 7, 2011 2:53 PM | Report abuse

raises hands and points/wiggles fingers toward the storm currently somewhere over texas(?) and chants:

shiiiift to the weeeest. shiiiiift to the weeeeest. shiiiift to the weeeeest... dooooon't goooo ouuuut to seeeeaaa. sloooow doooown and deeeeeevelop a voooortiiiicity looooobe (whatever that is). staaaaall ouuuut over faaaaalls chuuuurch.

Posted by: walter-in-fallschurch | January 7, 2011 3:10 PM | Report abuse

Dear Capital Weather Gang:
I want to formally apologize to everyone on the staff for my recent posts. They have been sarcastic and have bordered on personal attacks. And I want you all to know that I truly do enjoy the way that CWG presents the forecast (with the laymen and technical discussions) I think that the overall lack of snow in our immediate vicinity compared with direct hits that so many people have received all around us (Ocean City, Philly, VA Beach, Deep Creek Lake, Etc) has caused an alarming amount of anxiety and resentment towards others. And that resentment has culminated in to a few less then desirable verbal diatribes directed against CWG and Wes. So I am sorry.
So I have to tell you that I was more than delighted when I saw that your most recent post was entitled “Tuesday’s Snow Risk Increases”. The delightfully positive words that followed brightened my day and I want to thank you personally for that. So Wes… I have to give it to you… finally a forecast worth reading. Finally a positive analysis.
However… as I read through the post the smile on my face quickly turned to a frown as your true colors came storming back.
Wes, does someone really have to “put a gun to your head” for you to call for snow???? While many readers here probably skipped right through that statement interpreting it figuratively…I know the truth… and the truth is yeah… someone would have to put a gun to your head for you to call for snow five days in advance. Admit it Wes.
And then came the numbers… >1”, less than 4 inches???? Theys fighting words. This the same unadulterated crap that you jokers were spitting out in the days before the 12/26 storm. It’s embarrassing…… You basically said the chance for it to hardly snow or not snow at all has increased…. If you are not gonna hype, that what is the point of even posting the crap…
And for all of you that what to accuse me of “hiding behind the anonymity of the internet”… give me a call on my cell phone…. 443.527.2578. We can discuss.

Posted by: jac8949 | January 7, 2011 3:17 PM | Report abuse

Umm, awkward.

Posted by: HurricaneSpud | January 7, 2011 3:25 PM | Report abuse

That's a really nice apology "jac8949".
I'm sure Wes & all the gang appreciate it.

Posted by: FIREDRAGON47 | January 7, 2011 3:26 PM | Report abuse

Take it elsewhere Jac.

Posted by: JDK4 | January 7, 2011 3:36 PM | Report abuse

jac8949,
i think to get the kind of forecasts that would "delight" you, go to accuweather. they'll tell you we're due for 6-12" or something like that next tuesday. it's probably much more fun to forecast 12". i know it's more fun to read. who cares if it's an irresponsible forecast not justified by the best guidance? at least it's "delightfully positive".

Posted by: walter-in-fallschurch | January 7, 2011 3:39 PM | Report abuse

For storms like this I like to watch NAO. It is trending sharply upward and will be positive. That means progressive, so no blockbuster and possibly nothing. OTOH the AO is trending very negative so by the end of next week we should be looking a very cold blast, then an ice storm for next weekend.

Posted by: eric654 | January 7, 2011 3:46 PM | Report abuse

**crickets chirping**

I am not a huge snow lover but I do get a kick out of those who are. I also appreciate the rather clear and concise details about the storm and I know to expect a few inches while acknowledging we might not get anything.

jac8949 - I simply don't understand you. You disparage, degrade, and insult for no other reason that you don't hear what you want too. I believe that is this lovely thing called "real life". Temper tantrums are only valid when you are two or if someone took the last really good cookie - as this is not one of those situations, you are really just kind of sad.

Posted by: hereandnow1 | January 7, 2011 3:50 PM | Report abuse

raises hands and points/wiggles fingers toward the storm currently somewhere over texas(?) and chants:

shiiiift to the weeeest. shiiiiift to the weeeeest. shiiiift to the weeeeest... dooooon't goooo ouuuut to seeeeaaa. sloooow doooown and deeeeeevelop a voooortiiiicity looooobe (whatever that is). staaaaall ouuuut over faaaaalls chuuuurch.

Posted by: walter-in-fallschurch | January 7, 2011 3:10 PM |
---------------------------------------------
Walter, I completely agree. My hope is that it takes a drastic shift west, sucks up some moisture and hammers us with over 12". Now, the likelihood of that happening is probably about 2%, but hey, one can always dream! :)

Posted by: BobMiller2 | January 7, 2011 3:51 PM | Report abuse

I'm with you walter...too soon for dancing, but not too soon to try to conjure a big, whammy snow storm.

Posted by: manassasmissy | January 7, 2011 3:56 PM | Report abuse

this is becoming absurd... really. Definately an example of taking something a little bit too far. I want a huge amount of snow just as much as the next snow lover... but get a grip! I feel really bad for Wes and the other forecasters on this site for having to put up with nonsense like that. I for one respect all the hard work you put into this site guys, and enjoy hearing all the different perspectives from everyone. NO ONE can predict the future. It will snow again in the area sometime, we just should enjoy it when it happens. sigh

Posted by: rudy1481 | January 7, 2011 4:03 PM | Report abuse

jac8949: Were you showing us Hyde or the Doctor today? Where's that narcissistic Ophelia when you need her??

Posted by: kolya02 | January 7, 2011 4:06 PM | Report abuse

Looking at these super low dewpoints at DCA and IAD. Am I correct in thinking that will delay and hold down further the limited moisture that will come through tonight?

Posted by: HurricaneSpud | January 7, 2011 4:22 PM | Report abuse

I'm an eternally bullish on snow and for the first time I'm excited about the Tuesday situation.

My reasoning: There is a strong ridge off the West Coast and in the short range the models depict a pretty powerful (under 534) upper low over the Rocky Mountain States. There are even signs of the dreaded La Nina ridge off the SE US coast.

Normally, all these features would spell doom for DC area snow lovers in terms of running a storm up into the Great Lakes.

In this case, the unusual Arctic blocking appears strong enough to prevent that from happening. In fact right up to the most recent model runs, the blocking seemed to be overwhelming the storm and preventing much development.

Now the models are developing a storm over the South Central States which should ride up to at least Kentucky. Along with the coastal storm, the setup should produce a long easterly fetch of moisture off the Atlantic somewhat similar to the big storms last year.

Can things go wrong? Sure, it's still way to early to make definitive snowfall predictions. We could even change to rain.

But for the first time I see potential for a major event.

Posted by: frontieradjust | January 7, 2011 4:25 PM | Report abuse

@walter-in-fallschurch ... your first post was hysterical. Keep 'em coming, (Bworl-in-fallschuch)

Posted by: Bworl | January 7, 2011 4:30 PM | Report abuse

jac8949 was an abused child...

Posted by: Jamie66 | January 7, 2011 4:35 PM | Report abuse

Weather forecasting is at best an inexact science. Any snow forecast out beyond 3 or 4 days is basically speculation. Please don't get overly upset if the forecast isn't always right or to your liking.

There was a significant snowstorm on 12/26 that basically found a way to swerve right around us. No one could forsee that.

The forecasters are doing the best they can under difficult circumstances. They are providing an excellent service to the best of their ability.

Posted by: frontieradjust | January 7, 2011 4:41 PM | Report abuse

frontier adjust, please stop getting my hopes up so high...you're thoughts are so darn convincing...

And to those getting their panties up in a bunch, I'm pretty sure Jac is being facetious. To me it's just a bit of hyperbole.

But if I'm wrong...yeah I agree with walter...go watch some accuweather vids where they call for huge snows without any realistic probabilities of the event. The weather is not completely predictable; deal with it.

Posted by: bbirnbau | January 7, 2011 4:42 PM | Report abuse

I like the potential better than anything this season so far. So far this season we've had a lot of trouble getting enough ridging to help get a giant storm here and that seems to be the case still. So, I agree it's not likely big but some snow would be good.

Posted by: Ian-CapitalWeatherGang | January 7, 2011 4:47 PM | Report abuse

That was the worst apology I've ever read. What's the point in apologizing if you're going to do a 180 mid-paragraph? Why not just launch on the attack?

These guys stink at predicting weather but so does everyone else because even with all the nerdy tools and gadgets, people just can't predict the weather. At least therse guys provide some reasoning behind their waffling...

Posted by: spdawson1 | January 7, 2011 4:52 PM | Report abuse

@spdawson1

Wow. Thanks for having our back :(

-Dan, CWG

Posted by: CapitalWeatherGang | January 7, 2011 5:01 PM | Report abuse

1) Walter, I'm using my New Orleans voodoo to try and help you out. I miss your sculptures from last year.

2) CWG, I love y'all even when the snow is lame and doesn't show up to the party even though it promised you it would be there.

Posted by: kmill67 | January 7, 2011 5:08 PM | Report abuse

One of the most refreshing things about CWG is that they are willing to admit when they are not sure of a forecast and when they get a forecast wrong. I love all the analysis of why a forecast is difficult and the discussion that ensues.

Posted by: WickedRose | January 7, 2011 5:11 PM | Report abuse

frontier adjust, please stop getting my hopes up so high...you're thoughts are so darn convincing...
And to those getting their panties up in a bunch, I'm pretty sure Jac is being facetious. To me it's just a bit of hyperbole.
But if I'm wrong...yeah I agree with walter...go watch some accuweather vids where they call for huge snows without any realistic probabilities of the event. The weather is not completely predictable; deal with it.
Posted by: bbirnbau | January 7, 2011 4:42 PM | Report abuse
---------------------------------------------------
bbirnbau -
I agree, Frontier adjust's thoughts are indeed convincing, but if they're too much for you to handle, maybe you should skedaddle on over to AccuWeather.com; they'll get your hopes up even higher! :)

Posted by: BobMiller2 | January 7, 2011 5:15 PM | Report abuse

Hey guys, haven't been on this site since the dec. 26 storm, siiiiiigh... But i now have a new storm to root for... GO SNOW!!!!!!!!!

Posted by: SnowDreamer | January 7, 2011 5:17 PM | Report abuse

i'll be out of town this weekend, so i'm not getting too excited about saturday's snow.

tuesday's snow on the other hand... 'preciate any voodoo-type help i can get w/that one.

Posted by: walter-in-fallschurch | January 7, 2011 5:23 PM | Report abuse

the dude on nbc 4 said 1-2 tonight. more towards baltimore. but the the dude on cbs9 said some spots might not see any accumulation. big difference?

Posted by: fortheglory | January 7, 2011 5:42 PM | Report abuse

the dude on nbc 4 said 1-2 tonight. more towards baltimore. but the the dude on cbs9 said some spots might not see any accumulation. big difference?

Posted by: fortheglory | January 7, 2011 5:42 PM | Report abuse

Hey guys, haven't been on this site since the dec. 26 storm, siiiiiigh... But i now have a new storm to root for... GO SNOW!!!!!!!!!
Posted by: SnowDreamer | January 7, 2011 5:17 PM | Report abuse
-----------------------------------------------------------------
Do you mean to say that you only come on this site when there's a snowstorm?? Where's the team loyalty?? I'm on here every day! You do realize that this site doesn't only focus on snow, right?

Posted by: BobMiller2 | January 7, 2011 5:48 PM | Report abuse

Is it possible that I just heard Doug Hill say the words "big coastal storm"?? Just yesterday he was betting on just about nada.

Posted by: BobMiller2 | January 7, 2011 5:53 PM | Report abuse

Could someone please hit Walter with a tranquilizer dart? ;)

And, again, CWG - you have nothing to apologize for. Apparently some people don't know Murphy's law re Mother Nature.

Posted by: waterfrontproperty | January 7, 2011 6:26 PM | Report abuse

Jac obviously picked the wrong week to stop sniffing glue...

Anyone who thinks wxcasting is an exact science needs to go back and take a refresher course in the fickleness of Mother Nature. She does what she wants, when she wants, no matter how much we wish for a specific outcome.

I admit, I like snow, but I also recognize that we got a huge bonus package last winter...we might be left with a small box to play with this year.

Kim in Manassas

Posted by: ksrgatorfn1 | January 7, 2011 6:52 PM | Report abuse

The 18Z GFS was not very exciting, actually the NAM looked better to me.

Posted by: frontieradjust | January 7, 2011 7:32 PM | Report abuse

Everyone does realize that "jac" put his cell phone # on here, right?

Posted by: TheJoeGreene | January 7, 2011 10:59 PM | Report abuse

"... give me a call on my cell phone…. 443.527.2578. We can discuss."

Posted by: jac8949

-------------------------------------------

Who in the world would WANT to talk this nasty person?

Posted by: waterfrontproperty | January 7, 2011 11:29 PM | Report abuse

waterfrontproperty,

Agreed. Not worth anyone's time.

But I'd sure like to see his hand at a forecast... :)

Excited at the Tuesday potential... hoping it's more than 2-4 inches. But like Firedragon, I will get estatic around Monday night...

Posted by: MKoehl | January 8, 2011 1:40 AM | Report abuse

Oh goodness...

Out of curiousity I looked up jac8949's phone number... and found this...

http://www.washingtonpost.com/wl/jobs/JS_JobSearchDetail?jobid=29847517

There's a lot of job postings with this number on it... so I doubt it's his real phone number... why would someone use a business phone number...?

CWG, my two cents only, but you might want to label jac8949 as a troll and block him.

Posted by: MKoehl | January 8, 2011 1:51 AM | Report abuse

Hahaha I can't stop laughing at these comments. I personally think Jac is more upset over the headline hype than the actual predictions and forecasts.

I am a huge snow fan but I also don't do the shoveling in my house, can work from home if I need to, have all wheel drive and can still drop the kids off at daycare. Let's give some empathy to those who are mission essential/emergency personnel, do the shoveling, or don't have the luxury of 4 wheel drive.

Last year and early this year wasn't a typical DC area winter. I suggest racking up hotel points and frequentflyer miles, labeling your savings account "snowy day fund" and scheduling your time off now so you're prepared to hang out in a ski lodge somewhere across the country.

I love CWG, "Common-sense Weather Guys/Girls". Stop busting their chops and riding their jock at the same time. It's really not that serious.

Posted by: tressoleilgoddess | January 8, 2011 7:36 AM | Report abuse

First, the discussion concerns probabilities. Expressing probabilities offers an assessment of risk/confidence. A basic familiarity with those concepts would reveal that probabilistic statements are not identical to "waffling." Instead, they offer good insight into the magnitude of risk/confidence.

Second, if one regularly reads the CWG column, it is clear that the forecasts/discussions/predictions do not "stink." More often than not, they are on the mark.

Although it might be human nature to crave definite answers to questions as to whether it will or will not snow and exactly how much will fall, one should have a measure of patience until the critical details are known, as there remains a range of possible solutions. Most importantly, one should not lash out at others in frustration that their desire for certain outcomes and definite answers cannot be satisfied when the possible event is still outside the near-term.

Posted by: donsutherland1 | January 8, 2011 5:44 PM | Report abuse

The comments to this entry are closed.

 
 
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