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Posted at 5:00 AM ET, 01/23/2011

Forecast: Cold keeps a tight grip

By Brian Jackson

Primary precip type still in question for midweek storm

Today's Daily Digit
 
A somewhat subjective rating of the
day's weather, on a scale of 0 to 10.

 

Anyone tired of the chill won't be happy with another day struggling to reach 30.
 
Get the 'Digit' on Twitter

EXPRESS FORECAST

Today: Cold, bit of a breeze. Mid-to-upper 20s. | Tonight: Mostly clear, biting cold. Near 10 to mid-teens. | Tomorrow: Still cold. Upper 20s to near 30 at best. | A Look Ahead | Get Express Forecast by E-mail

FORECAST IN DETAIL

Just in case you were worried yesterday's cold would lose its punch, today brings a reinforcing cold front and a similarly powerful chill - with a bit of a breeze to boot. The cold remains the story until a coastal storm threatens midweek. Whether we get precipitation and what kind - snow, wintry mix, rain, or all of the above - depends, as usual, on the storm's still uncertain timing and track.

Snow Potential Index: 5 (→) - We're still following the potential for some snow Tues/Wed (now probably late Tues/Wed), but plenty of "ifs" mean low confidence.

 
The SPI is a daily assessment of the potential for accumulating snow for the next week on a 0-10 scale. Get the 'SPI' on Twitter
 

Temperatures: Latest D.C. area temperature map powered by iMapWeather (base map by Google). Click and hold on map to pan. Double-click to zoom. Refresh page to update. See larger map on our Weather Wall.

Today (Sunday): A weak cold front struggles to bring us any visible effects in the form of precipitation or clouds - in fact, skies should be partly to mostly sunny. Still, the non-visible effects are quite noticeable. We stay very cold with highs similar to yesterday in the mid-to-upper 20s. Add to that, winds from the northwest around 10-15 mph at times with some afternoon gustiness. Confidence: High

Tonight: We're in for one of the - if not the - coldest nights of this winter. With mostly clear skies, really low dew points and little wind, overnight lows could dip into the single digits in some of our more rural areas, and the low-to-mid teens for everyone else. All in all, a pretty good night to fire up the fireplace if you've got one. Confidence: High

Keep reading for the forecast into the coming work week, including the latest on our snow chances for midweek...

Tomorrow (Monday): We start the work week the way we finish the weekend - cold. One improvement over Sunday is a less noticeable breeze. Though with highs in the upper 20s to near 30 at best, I don't think many will find much solace in that. Clouds may increase some as the day goes on. Confidence: Medium-High

Tomorrow Night: Partly to mostly cloudy skies should be insulating enough to put an end to the mini-streak of bitterly cold nights. Lows only drop to the low-to-mid 20s thanks to the clouds and a warmer southerly flow. Confidence: Medium-High

A LOOK AHEAD

A disturbance to our north may bring a flurry or two early Tuesday, but odds are that any significant precipitation doesn't begin to affect us until Tuesday evening or overnight. If partly to mostly cloudy skies allow just enough breaks of sun, highs could break past 40. Otherwise, highs probably stay in the upper 30s.

Precipitation chances increase Tuesday night, especially during the overnight and toward dawn, as a coastal low-pressure center takes shape to the south and lows dip to around freezing. Some snow is likely to start. But with no strong high pressure to our northeast to hold in the cold air, any snow may eventually change to a wintry mix and/or rain as we get into Wednesday, unless the storm takes just the right track for all snow or mostly snow. Wednesday's overall chance of precipitation is about 70 percent (so, a 30% chance the storm misses us altogether) with highs in the 30s. Confidence: Low

By Brian Jackson  | January 23, 2011; 5:00 AM ET
Categories:  Forecasts  
Save & Share:  Send E-mail   Facebook   Twitter   Digg   Yahoo Buzz   Del.icio.us   StumbleUpon   Technorati   Google Buzz   Previous: Strong storm chance Tues-Wed, snow odds unsure
Next: Latest on the Tues night-Wed storm threat

Comments

Madame Olga could do just as good a job, if not better. At least she'd use a tambourine for emphasis. Let's face it - CWG watches radar and gets their jollies over models that frequently conflict with each other, populates forecasts with "may's" and "could's," then keeps tweaking the forecast until whatever it is actually gets here, then explains why everything they told us would happen didn't. If this sounds familiar, it should - they're in the same class as Metro escalator repairmen.

Posted by: hofbrauhausde | January 23, 2011 6:41 AM | Report abuse

This is what happens when you tease us with the probability of rain:

http://www.youtube.com/watch?v=AKGPvul8FXc

Posted by: RedCherokee | January 23, 2011 6:45 AM | Report abuse

@hofbrauhausde

We'd welcome you to forecast against us head-to-head any time and/or present to us consistently better forecasts from another outlet (gov, media or otherwise).

Posted by: Jason-CapitalWeatherGang | January 23, 2011 6:53 AM | Report abuse

Wow- pretty big east push with the NAM and GFS in overnight runs. GFS out to sea...

Posted by: Jason-CapitalWeatherGang | January 23, 2011 7:04 AM | Report abuse

Hey brian... when looking at the models, what feature bests depicts the rain snow line. I hear it is the 540 line but I dont know where to look for that. Is the 0 degree c at 850 mb reliable? That is easy cause it is a big fat blue line on the gfs :)

Posted by: jac8949 | January 23, 2011 7:18 AM | Report abuse

@hofbrauhausde I thought the same way when I first started reading this blog. Then I sat back and watched them to see how they verified. They have been dead on so far this winter. It seems like they have a conservative bias for no snow, but in fact, the pattern for us just has not been setting up right and they are calling it like they see it. Good Job CWG!

Posted by: jac8949 | January 23, 2011 7:24 AM | Report abuse

My best guess is the deep moisture is going out to sea, the pattern is too progressive to get the south to north flow we need. Then the question is how strong will the storm be as it passes east of us. I'm not sure it will be strong to get the heavier precip needed to cool the lower atmosphere. I'm going to predict wet snow with only some accumulation on Wednesday with dim sun poking through by the afternoon. But I sure hope the models change and move everything back to the west.

Posted by: eric654 | January 23, 2011 7:44 AM | Report abuse

Moving it back west...umm. Well, how about we move it to Warren County? I'm relieved to have a dry season in JeffCo. Easier on the house. All I want is enough precip to keep the field from catching on fire.

Posted by: tinkerbelle | January 23, 2011 7:52 AM | Report abuse

Jeeze, hofbrauhausde -- if you're so unhappy with CWG and their work, why do you keep coming back?

Posted by: natsncats | January 23, 2011 7:55 AM | Report abuse

"Wow- pretty big east push with the NAM and GFS in overnight runs. GFS out to sea..."

Does that mean we are more likely to miss the moisture altogether?

Posted by: pxw22 | January 23, 2011 7:56 AM | Report abuse

Unfortunately whatever Warren county gets, Jefferson does too. What do you mean by easier on the house? I was just out looking at the ground yesterday and the top few inches is pretty dry and could use some rain or snow (preferably snow since it soaks in better as it melts). But I can deal with whatever we end up with, wet or dry.

Posted by: eric654 | January 23, 2011 8:05 AM | Report abuse

I'll be out of town for a two weeks, so as a snow starved snow lover - I predict at least one decent storm if not two. So Tuesday-Wedensday I'd say 4-6" in DC. I'll also go out and predict that Feb 4-5 we'll get 5" and it'll delay my return and enjoyment of the snow.

Posted by: Bainbridge | January 23, 2011 8:13 AM | Report abuse

Something for us all to keep in mind- there still has not been even a single run of ANY model that shows us getting a big snowstorm.

Some have trended further east and a little colder, but take the heavy precip with it, and some have stayed further west with lots of precip but warmer air. CWG- this seems like a situation where our only chance of staying all snow is if we take the lesser amounts of precip that come with a glancing blow. There just doesn't seem to be enough cold air around this go around.

Also, don't even bother responding to the trolls. The other weather sites have folks go to reasonable weather outlets (like this one) and leave crazy comments, if you respond it only lets them know their tactic is working. HA

Posted by: 4seamed | January 23, 2011 8:14 AM | Report abuse

Weather is inherently a dynamic phenomenon. What sense does it make to make an iron-clad projection several days out? It's far better to explain all the possibilities and the likelihood of each based on the current data. As the data changes over time the probabilities change accordingly. No one is trying to be Nostradamus here. If you want that type of forecasting, a better place would be AccuWX. However, you'll often their projections to be a complete bust and without any explanation why.

Posted by: bdeco | January 23, 2011 8:14 AM | Report abuse

I think the problem some folks have with forecasting is their lack of understanding into the knowledge/skill/education that goes into atmospheric science. One of the BIG problems is the perception that all you have to do is stare at what the computers spit out every six hours, change your forecast to match it, rinse and repeat. Just read this form this morning's NWS discussion for our area.

MDLS HV HAD GRT
DIFFICULTY W/ CSTL STORMS THIS SEASON...AND UNFORTUNATELY THIS ONE
MAY HV THE GREATEST MDL DIVERGENCE OF ALL..SO WE`LL ALL WAIT AND
SEE HOW THIS STORM DVLPS NAD MAKE ACCORDING CHGS TO THE FCST. STAY
TUNED.

Doesn't this sound like "the models aren't giving us the answer, so we will just wait to see what shows up on radar and observation and then change our forecast."

While I don't need an ironclad prediction this far out, I would like to see mets use their history books and education and combine that with the models to come up with a best case scenario.

Posted by: 4seamed | January 23, 2011 8:23 AM | Report abuse

High temperatures yesterday were in the mid to upper 20's at the three airports, not where I live in surburban upper Montgomery County, MD. Last I heard, very few people if any, live in airport like environments (miles of cleared land with no vegetation, 600 degree jet exhaust, stronger winds, and low elevations).

I run a National Weather Service published climate station in Montgomery County, MD. My high yesterday was 20.1 degrees F.

I'm at 700 feet elevation versus Dulles, the highest AP being under 300 feet. The average elevation in Mont. County is over 500 feet. My sensors are located near the ground where human activity occurs, not on a heated rooftop or near a huge black asphalt runway.

Wish you guys would look at non-airport data a little more when you summarize conditions.

Official NWS data (including many non-airports that count in the record books are published every morning around 9 am by the local NWS forecast office at:

http://www.srh.noaa.gov/data/LWX/RTPLWX

Posted by: mdweather | January 23, 2011 8:27 AM | Report abuse

The euro would be a dream come true for me because 1. It shifted west (more precip) 2. The rain snow line would be in E loudoun, so I'd probably get all snow or mostly snow.

I don't know what's up with the GFS... Should we continue to disregard its forecasts? This will probably be another wait and see storm...sigh...

Posted by: BobMiller2 | January 23, 2011 8:27 AM | Report abuse

mdweather-

I'm with you, the validity of measurements is an issue you just can't get enough people to pay attention to. There is an organization that has a dedicated project to make sure instruments are being used properly and placed in the proper location (not sitting under a heat exhaust, on a blacktop parking lot, etc) where folks go to NWS reporting locations to inspect and take pictures, but I won't link to it here since so

Posted by: 4seamed | January 23, 2011 8:36 AM | Report abuse

Jason - what does the push east mean (NAM, GFS)? I suppose it means rain....

You are going to start hearing much ranting and raving from the Crofton area soon if we don't see some snow....

Posted by: nolagirl67 | January 23, 2011 8:54 AM | Report abuse

Jason - what does the push east mean (NAM, GFS)? I suppose it means rain....

You are going to start hearing much ranting and raving from the Crofton area soon if we don't see some snow....

Posted by: nolagirl67 | January 23, 2011 8:54 AM | Report abuse

Jason - what does the push east mean (NAM, GFS)? I suppose it means rain....

You are going to start hearing much ranting and raving from the Crofton area soon if we don't see some snow....

Posted by: nolagirl67 | January 23, 2011 8:56 AM | Report abuse

Snow flurries with bright sunshine in Oakton, VA.

Posted by: Kevin-CapitalWeatherGang | January 23, 2011 8:57 AM | Report abuse

Jason - what does the push east mean (NAM, GFS)? I suppose it means rain....

You are going to start hearing much ranting and raving from the Crofton area soon if we don't see some snow....

Posted by: nolagirl67 | January 23, 2011 9:00 AM | Report abuse

nws has dulled back precip. report to around 1.3" liquid for IAD...
http://www.hpc.ncep.noaa.gov/qpf/day4-5.shtml

the imfamous wxrisk.com articles are out, this one says IAD will be in an area of uncertainty, but is only about 60 miles away from the 6-12" zone!!!!!

Posted by: SnowDreamer | January 23, 2011 9:02 AM | Report abuse

Snow flurries in a bright blue sky in Merrifield, VA, as well! I can see some large thin clouds just off to the west, so I assume that's the source.

Posted by: --sg | January 23, 2011 9:04 AM | Report abuse

jac8949 - the 850 0 line is a better rain-snow line than 540 thickness but it doesn't always work (esp when we have boundary layer temp issues)

Bobmiller - yes if anything is "certain" it is that this is a wait and see storm. As we see the weather models jump around, we have to keep clear, analytical heads. Why the jumps around? The atmosphere is uncertain what mode it wants to enter into...the storm is a manifestation of a lot of atmospheric energy, but too much is misaligning for a consistent output by the models. Will keep you posted!

Posted by: Camden-CapitalWeatherGang | January 23, 2011 9:12 AM | Report abuse

@Kevin: Snow flurries with bright sunshine in Oakton, VA.

Apparently we had flurried here at Worldgate-Herndon VA too according to mitchrapp...

Posted by: kygurl94 | January 23, 2011 9:14 AM | Report abuse

Reston, VA - 24 degrees, light snow falling with a light dusting on surfaces, and...partly sunny (odd).

Jason/Gang - I'm not surprised to see a model throw this storm out to sea. I'm feeling pretty confident in another trace to an inch storm here. what are the odds of that again? Given the 2010/2011 winter pattern. I understand we could also likey see the opposite...a western track that brings snow, mix, and rain.

Posted by: parksndc | January 23, 2011 9:37 AM | Report abuse

@Brian Jackson. You might want to rephrase the suggestion that this is a good time to build a fire in the fireplace. That's a prescription for freezing the pipes, since fireplaces mainly draw outdoor air into the house through the basement in many homes (while contributing no net heating).

It would be a good time to fire up the woodstove or indoor jacussi, however.

Posted by: jimtitus1 | January 23, 2011 9:37 AM | Report abuse

@4seamed

That's just not true. There have been multiple runs of both the Euro and the GFS that have shown good snow storms for us. Not to mention the ensembles have been the most consistent of all to show snowstorms for us.

That being said, the latest NAM and GFS runs are a huge kick in the groin. We go from too far inland for snow to OTS...there's no winning here.

Posted by: bbirnbau | January 23, 2011 9:42 AM | Report abuse

I think I am jealous of the Virginia flurries you all report! Nothing but sunny skies here in downtown DC. Only other flurries I can spot on high-def radar are near Hagerstown & Front Royal.

Posted by: Camden-CapitalWeatherGang | January 23, 2011 9:45 AM | Report abuse

I just did a snow flurry photo shoot. With this season, I have to take any opportunity I can get. It snowed for about 30 minutes in the Oakton/Vienna area which briefly dusted the ground. Much of the time there was blue sky above.

Posted by: Kevin-CapitalWeatherGang | January 23, 2011 9:46 AM | Report abuse

So whats the deal with the latest GFS run, is it still the outlier or is it onto something because thats a beautiful miss! If it keeps trending east itd be great for no snow, but if it trends west in the next couple runs it could be a direct hit, although im not sure how much warm air it would bring.

Is the GFS still having errors or is it the1st to pick up on the final solution? BTW, the current GFS solution is the one thats happened time and again this winter season thus far.

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/06/images/gfs_slp_096m.gif

Posted by: KRUZ | January 23, 2011 9:47 AM | Report abuse

Btw, I had 9 degrees last night before I went to bed...that's ridiculous.

Posted by: parksndc | January 23, 2011 9:49 AM | Report abuse

Flurries and sun in Herndon during a very COLD run this morning.

Posted by: veronica7 | January 23, 2011 9:49 AM | Report abuse

pretty funny how pretty much everything seems to still be "on the table". we could have anything from nothing to a big snow storm to rain, sleet and maybe freezing rain... hahahah boy....wanna see a snow hole? watch this loop. warning: NOT for the faint of heart. you may want to shield your children's eyes.

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/06/index_p48_m_loop.shtml

let's hope THAT doesn't verify! watch that a few times and it'll make snowlovers happy with a piddly little 3" storm. hopefully there's still something wrong w/the GFS or it's an outlier or something... sigh...

Posted by: walter-in-fallschurch | January 23, 2011 9:49 AM | Report abuse

12Z NAM has the border line for a major snow/rain storm cutting right through the DC area. Obviously it's just one run, but it highlights the continuing uncertainty with this system.

Posted by: bdeco | January 23, 2011 9:57 AM | Report abuse

12z NAM looks promising for precip., but we are right on the rain snow line during the heaviest precip.

Posted by: snowlover | January 23, 2011 9:57 AM | Report abuse

The GFS has been the first to pick up on the correct or final solutions almost every time this year. The NAM followed the GFS fairly rigidly in its past two runs, maybe a slight Nward shift in its last run.

If the 12z GFS runs OTS, I'm done with this one. We are inside 72 hours and it looks like they are coming into agreement. It's hard to take into account what the Euro will do because it's been pretty bad this year. Nevermind the Canadian altogether.

CWG you've done a fantastic job this year, looks like the first mis forecasted event for you guys being that you called for a 70% chance of precip. But I'm not complaining. Guidance showed nothing over the past few days to suggest an OTS solution until right now. What a terrible winter to be a met.

Posted by: bbirnbau | January 23, 2011 9:58 AM | Report abuse

KRUZ - to chaotic for all models to grasp. No "final solution" to be labelled yet.

parksndc - wow single digits? Very cold. You must be outside the Beltway for that, right? Only 20 downtown last night, from what I can tell was the low.

veronica7 - yes, cold! And you were one of the lucky few out there to have flurries this morning.

Walter, you have good humor as always

Posted by: Camden-CapitalWeatherGang | January 23, 2011 10:01 AM | Report abuse

@4seamed If by history books you mean looking at similar storms in similar environments from the past, that's not a great way to forecast. In fact, analog forecasting has the least predictive skill of any type of forecasting.

The fact remains, these highly sophisticated computer models are the best tool we have for predicting the weather. Meteorologists have spent decades refining these models as they learn more about the processes in the atmosphere and its interaction with land and sea. As more research is done (and it certainly will given the chaos this Winter), changes and updates will be made in an effort to increase the accuracy of these models. In the end, we can't account for every single process that occurs in the evolution of a storm. That's why ensemble forecasts have grown in popularity in recent years. They allow us to see if the single model run is one we can have confidence in. Unfortunately, that doesn't seem to be the case for this storm. Last year was a different story.

What is interesting about this storm is that the GFS ensemble means have been consistent in bringing the storm up the coast and creating a primarily frozen precipitation event for our area. The HPC seems to favor this solution as their forecasts for the last couple cycles have reflected this prediction. If this were to pass, it would be a big victory for NCEP and Dr. Louis Uccellini, who have been pushing ensemble forecasting for the last several years. (Obviously, ensembles aren't that necessary when models are consistent and agreeable, but it would be interesting to see if they have value in these situations.)

And as I finish typing this, the 12Z NAM has brought the storm right up the coast and the 0C 850mb line right over DC - very similar to the GFS ensemble mean and a nightmare for forecasters. In the same presentation I saw Dr. Uccellini pushing ensemble forecasting, he referenced a busted forecast from the early part of this century. In forecasting for the east coast, they determined a significant snowstorm was coming. Schools, governments, and businesses closed. It rained. Ever since, Dr. Uccellini has expressed the need for meteorologists to be honest about the uncertainty in forecasts. So if you're looking for someone to walk out on the edge and make a bold prediction, don't expect it. Better yet, don't listen to it. Anyone making a confident forecast for DC at this point has nothing to base it on.

Posted by: Steve-wxtalkwordpresscom | January 23, 2011 10:02 AM | Report abuse

jac8949 and Camden, Sorry, but I'm going to have to disagree on the 850mb 0-degree line being a good indicator for snow, but, I don't like the 540 thickness (1000-500 mb) line either. Both are far too general to make a confident forecast of snow off of. I go nuts when I see folks looking at a model forecast with 850mb temperatures and they start screaming "Snow!"
While both are an ok starting point. I have faults with both. In a typical atmosphere, with minor variations, temperature decreases with height, so, if it's 0 degrees at 850 mb, it's logical that the surface would be above freezing. Now, the thing that gives it creedence around here is that our snow events typically occur with a "cold-air damming" event which holds a shallow layer of cold air near the surface, so with 850 mb temperatures at or below freezing, we're likely going to remain below freezing at the surface.
With the 540dm line on the 1000-500mb thickness chart, again, it's a good indicator, but its a bit broad. The profile may contain warmer and colder layers within it that could alter precipitation types, though at 540 or below, some type of winter precip(snow, sleet, freezing rain) is likely.
I prefer to use both the 1000-850 thicknesses (132dm) and the 850-700mb (152dm). This gives a more detailed look at the temperature profile. If we have both of the layers below those critical thickness numbers, snow is likely. If the 850-700 layer is warmer, but the 1000-850 layer is still cold, some snow is still possible but we are more likely to see freezing precip (sleet/freezing rain). With the surface warmer, and the 850-700 layer still cold, we may see some rain/snow mix that melts quickly, or all rain. When both are warmer, rain is likely.
Here are some examples from this mornings (interesting)(12z) NAM run:
850mb temp:
http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/nam/12/images/nam_pcp_084m.gif

At 84 hrs, we look like we may be in for a pretty good wallop, the 0 degree line is right over or just to the SE of DC by a matter of a few miles. Looking at only this, one may be inclined to call for snow, but with a lot of uncertainty since warmer temps are very very close.

1000-500mb:
http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/nam/12/images/nam_slp_084m.gif

At the same time, the 540 line is well north of the area and we are looking at thicknesses of 546dm which signals liquid precip.

1000-850mb and 850-700mb:
http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/nam/12/images/nam_sl8_084m.gif
http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/nam/12/images/nam_sl7_084m.gif

From these we can see that the surface layer is plenty cold(132 line all the way down to FL/GA border) but the mi-levels (850-750) are warm, 152 line back in OH/PA, showing a more snow/sleet/freezing rain threat this run.

Posted by: Brian-CapitalWeatherGang | January 23, 2011 10:03 AM | Report abuse

@bbirnbau one run of the 6z (off hour) GFS 3 days out shouldn't make you give up on a storm. The 0z GFS gave us all snow and like a foot. No way you can call this a blown forecast at this point.

Posted by: samdman95 | January 23, 2011 10:04 AM | Report abuse

Centreville VA Went down to 12 here last night. Breezy & bitter; lots of fast moving clouds but no sign of flakes.
Do not like.

*reads forecast, gnashes teeth, pulls hair*

Posted by: FIREDRAGON47 | January 23, 2011 10:07 AM | Report abuse

BobMiller2/spgass1

Still killing several stinkbugs a day! I guess they want to be in my nice toasty house. Can you make me a coconut sized coffin!!

Posted by: worldtraveler83 | January 23, 2011 10:08 AM | Report abuse

Camden - Reston, VA...the temp just started plummeting around 8pm and it was getting colder rapidly. I think it leveled off at some point and began to rise overnight though b/c we were at around 23 when I woke up this morning.

Posted by: parksndc | January 23, 2011 10:15 AM | Report abuse

@bbirn

I guess "good snow storm" is pretty subjective. There have been runs that have shown heavier precip that may have included some sloppy mix, but none have snown an all snow storm with anything more than a few inches of snow.

The good news is that the NAM actually produced the best run for snow yet! There is still hope...

Posted by: 4seamed | January 23, 2011 10:18 AM | Report abuse

samdman95 - I don't know where a foot is coming from and I'm not sure when anyone mentioned a "blown" forecast...what forecast are you referring to? I feel like some of the snow lovers (and I am one) on here are reading forecasts of their own sometimes…over-hyping something that isn’t even real.

Posted by: parksndc | January 23, 2011 10:21 AM | Report abuse

@ parksndc this is bbirnbaus quote i was reffering to "CWG you've done a fantastic job this year, looks like the first mis forecasted event for you guys being that you called for a 70% chance of precip. But I'm not complaining. "

Posted by: samdman95 | January 23, 2011 10:29 AM | Report abuse

Hey Everyone, how often do these runs from the different models come out? Keep us updated on the NAM runs, and other runs to see what they say now that we are getting closer to game time!!!!

Posted by: RJ16 | January 23, 2011 10:35 AM | Report abuse

@RJ16 NAM and GFS models are run every 6 hours, although the morning (!2Z) and evening (00Z) runs tend to carry more weight as they contain a full batch (so to speak) of new information.

Posted by: Steve-wxtalkwordpresscom | January 23, 2011 10:39 AM | Report abuse

Now we just wait for the 12z GFS. It'll probably still say OTS, but I still think this storm will ride up the coast. Right now, I think we're all more concerned about precip type more than anything. We lucked out last year as we never had to give precip type a second thought.

@worldtraveler83

Hopefully whatever snow we DO get will bury the stink bugs and kill 'em all! I found one on my window this morning and boy, you better believe it was down the drain before you could count to three!

@bbirnbau

What do you mean the models are coming into agreement?? The GFS ensemble means are all over the place, and with each and every run of each and every model, things change. This is by no means a done deal and at this point, there are still many possible scenarios on the table.

@Camden & parksndc

Here in sterling, we got down to 8.7°F late last night. Temps really took a nose dive.

@Walter

Something tells me that there won't be a snow hole this time around. That's my take on it; I'm probably wrong...


@firedragon

We had some pretty big flakes here this morning...just enough to barely coat the ground.

@SnowDreamer

You do realize that 1.3" is equal to 13" of snow, don't you? I'm not sure what the NWS is basing those qpf maps off of as none of the models are predicting that much.

@CWG

What time will the next update come? Still too early for an accumulation/zone map, right?

Thanks,
Bob


Posted by: BobMiller2 | January 23, 2011 10:42 AM | Report abuse

**********We are going to get snow and all snow. Its 15 degrees today. I don't think that these temps will be above freezing by Tuesday. We are getting a major SNOW STORM. EVERYONE GO OUT AND BUY MILK, BREAD, AND SNOW BLOWERS. GET READY FOR THIS. ITS GONNA BE THE STORM OF THE CENTURY!!!!!!!!!! *********

P.S.
CWG,

When is the next updated forecast today?

Thanks!

PRAY FOR SNOW!!!

Posted by: SNOWLUVER | January 23, 2011 10:42 AM | Report abuse

@RJ16

NAM and GFS are every 6 hours. Although from what ive heard, the NAM is very unreliable until its within 48 hours or even 24 hours. Maybe CWG can comment on that assumption.

Posted by: KRUZ | January 23, 2011 10:42 AM | Report abuse

Brian... thank you soo much for your explanation. That is pretty awesome that you went in to that much detail.

Posted by: jac8949 | January 23, 2011 10:43 AM | Report abuse

I'm way confused with these model run this morning, are the model leaning toward warmer air which means RAIN, or at this point it will start off as snow then changing to whatever.....

Also I'm hearing the storm has back off hearing it might be Wednesday into Thursday now...

With the latest run, what are they showing??

I see TWC is still forecasting Snow/Wind on Wednesday, and Snow on Tuesday Night.....

Posted by: Michael_Nguyen | January 23, 2011 10:44 AM | Report abuse

And you heard it here first, 3 - 5 inches for Montgomery County. I, unlike all the Mets, predict Weather the old fashion way. 3-5 inches for moCo and 1-3 for dc. You heard it from CRJG capital RJ gang first.

Posted by: RJ16 | January 23, 2011 10:45 AM | Report abuse

Here's what Justin Berk had to say this morning:

Look at the arctic reinforcement on the way. As for the computer models... the GFS may come back in line today or tonight... This arctic air will not move ...out that fast. It will moderate as the storm arrives, but snow or ice- at least for the start will be a major concern. Don't hug the models today.. watch the energy diving south and how/where storm develops in the Gulf through tomorrow.

Here's some of what Joe Bastardi's latest blog post (he talks about his "misses" this year...and why they happened):

WHILE MODELS TREND WEST, GFS TRENDS EAST.

No changes folks on the idea of a storm coming up out of the gulf in the Tuesday Wed period. The track should be inside Hatteras and Cape Cod, meaning heaviest snows are probably west of the big cities. I believe the GFS and its ensembles are having major problems with the energy considerations, the usual problem of trying to keep too much in the northern branch. The euro ensembles have the right idea in my opinion and are closest to mine. They have a slower initial evolution, with more energy further back in the southern branch.

I cant tell you how torturous it is to work with this model. I have been watching it in the plains where I have to try to fight its preloads in the energy business. Today, it had a 40 degree turn in the day 10 temps in southern Canada. Last Friday it had temps near International Falls near 20 ABOVE NORMAL for Monday jan 31. They are now over 20 below. 20 degree changes in the northern plains are needed for the early part of next week. Its a constant war with seeing how bad this is. Since I have to work with it every day, and try to fight its preload, its torture, pure and simple. I have told my clients for instance, that a 10 day european weekly in the plains, for lets say days 10-16, will beat the GFS ensembles the week of the forecast in question! Again I wish I had the moveable type here to show you. Though I was late by my standards ( and yours) I did catch the Jan cold before the fact, putting out a forecast on New Years eve ( I busted my tail Christmas week, outside of snow shovelling with my dad and son, it wasnt a very merry week) and put out a forecast for Jan to be the coldest for the nation since 1985. As it is, only 1994 may be able to stop that ( the month was -2.6 right now by the same measuring standards we are -2.1 but this is going to be close) At the same time, the GFS ensembles were constantly trying to push warmth out into the plains. Right now there is no one east of the rockies above normal in the plains. This "push" east of the weather, be it a storm off the east coast, or taking the core of warmth out of the rockies, is a constant problem. I work 7 days a week, and have to look at it every day. Perhaps that is why I am seeing this. If you have an 9 to 5 job 5 days a week, and lets say just looking at statistical verifications of the model or tweeking it, you arent as acutely aware.

Posted by: DLO1975 | January 23, 2011 10:53 AM | Report abuse

Dr. Tracton,
If Dr. Uccellini is gung-ho about ensemble forecasting, why is the high-resolution GFS run out to 384 hours, 4x per day? Granted it drops in resolution beyond 192hr, due to marginal skill at these long-range times. Wouldn't it be more efficient use of HPCC resources to limit GFS hi-res runs (2x/day) and run more low-res versions of the GFS instead for ensemble forecasting? I never heard the rationale for the current scheduling of the NCEP's models.
Thanks!

Posted by: klasskalmen | January 23, 2011 10:57 AM | Report abuse

CWG- Have you guys noticed the outstanding agreement on the low placement at hour 96 on the 12z NAM and the 00z Euro and the 00z GFS ensemble? How significant is it that we have agreement with these three runs and as a result, do you think that we will start seeing more confidence in the forecast? Also- one of the things that I am seeing on the models is cold air being drawn into the storm on its SW quadrant... it looks like the Euro goes really cold at hour 96, but all three models show cold air coming back in to it. Since there will be no Real Blocking, what do you guys think the models are picking up on? Could it be the surrounding cold from our NW?

Posted by: jac8949 | January 23, 2011 10:57 AM | Report abuse

Dear CWG,
I just wanted to chime in and thank you for all your excellent work. Yours is the first place I turn in the morning to check on the weather. Despite what others might say, I have found your forcasting to be spot on 99.9 percent of the time. While I have been disappointed at the lack of snow this year (last year set a pretty high benchmark), I have not been in your reporting of these very tricky situations. I think all snow lovers can sometimes suffer from "confirmational bias", in that we look for what we want to happen and are disappointed when it doesn't, but that's our problem. Although I do like the idea of tambourines all round, what do you say? Anyway, thanks for and keep up the splendid job!

Posted by: cgindc | January 23, 2011 11:02 AM | Report abuse

Dear CWG,
I just wanted to chime in and thank you for all your excellent work. Yours is the first place I turn in the morning to check on the weather. Despite what others might say, I have found your forcasting to be spot on 99.9 percent of the time. While I have been disappointed at the lack of snow this year (last year set a pretty high benchmark), I have not been in your reporting of these very tricky situations. I think all snow lovers can sometimes suffer from "confirmational bias", in that we look for what we want to happen and are disappointed when it doesn't, but that's our problem. Although I do like the idea of tambourines all round, what do you say? Anyway, thanks for and keep up the splendid job!

Posted by: cgindc | January 23, 2011 11:02 AM | Report abuse

@RJ16

CRJG capital RJ gang > CWG


Posted by: SNOWLUVER | January 23, 2011 11:02 AM | Report abuse

CWG- Have you guys noticed the outstanding agreement on the low placement at hour 96 on the 12z NAM and the 00z Euro and the 00z GFS ensemble? How significant is it that we have agreement with these three runs and as a result, do you think that we will start seeing more confidence in the forecast? Also- one of the things that I am seeing on the models is cold air being drawn into the storm on its SW quadrant... it looks like the Euro goes really cold at hour 96, but all three models show cold air coming back in to it. Since there will be no Real Blocking, what do you guys think the models are picking up on? Could it be the surrounding cold from our NW?

Posted by: jac8949 | January 23, 2011 11:03 AM | Report abuse

@ jac8949 -----> with the statement you said, that most model have the low placement in the same location, well I'm assuming with the latest run, is that good forecast for the DC Area??

I think this winter is hard for these model to come into the most agreement... Are we still in the forecast for some heavy precip or light whatever falls from the sky??

Posted by: Michael_Nguyen | January 23, 2011 11:05 AM | Report abuse

Howard Bernstein from WUSA 9 just made a prediction on twitter: "Believe we will see a snow to rain event tue pm into wed. May stay all frozen toward I-81.

Sounds like typical winter wx in DC.

Posted by: KRUZ | January 23, 2011 11:12 AM | Report abuse

In all honesty, I am a teacher and I can always feel it when we are about to have a snow day off. That being said, my spider senses are tingling and I can already tell that there will be no school on Wednesday. I'm 88.3456 percent accurate. I also have my own model that I run at home, birds and the wild life. Their behavior indicates that Snow is coming my friends.

Posted by: RJ16 | January 23, 2011 11:17 AM | Report abuse

The 12z GFS is finally moving further west...

Posted by: BobMiller2 | January 23, 2011 11:18 AM | Report abuse

@ Brian

Thanks for the information. You explained clearly something that i've been trying to wrap my head around for a long time.

Posted by: bdeco | January 23, 2011 11:23 AM | Report abuse

The 12z GFS is also a lot colder. Interesting to see what the temps look like on the 18z NAM.

Posted by: MVPlaya8120 | January 23, 2011 11:25 AM | Report abuse

@ Michael_Nguyen - well I am trying to get feedback from CWG on the actual forcast. I can tell you that the agreement in the models placed the low off the coast of Atlantic City with the 850 zero degree line either right over us or too our east. At least they are not showing an inland track. Now in terms of SNow or Rain... I have no clue. The analysis of that is too dynamic for me to figure out. I think that if the models come in to agreement 2-3 runs in a row and the track is good for snow, then we will likely hear from CWG that the confidence for snow has risen slightly.

Posted by: jac8949 | January 23, 2011 11:28 AM | Report abuse

I think we are going to get all snow in Falls Church Va.

Posted by: weatherfreak1994 | January 23, 2011 11:38 AM | Report abuse

I think we are going to get all snow in Falls Church Va.

Posted by: weatherfreak1994 | January 23, 2011 11:39 AM | Report abuse

The latest GFS definitely has to raise some hope for snow. Temps far cold enough to support snow along 95, precip just a tad too far east to give us a good thump. But the big question is what the Euro does this afternoon. The Euro has been a tad warm with temps lately so I think it's more important to look at the track of the low rather than precip types right now. If the Euro still gives the track it's been giving then we are starting to come into agreement with where this storm is going to go. Then we will have to pour over thermal profiles to see where the 850 line sets up. VEERY inaraesting.

Posted by: bbirnbau | January 23, 2011 11:40 AM | Report abuse

I think the analysis and forecast here is good. For me the best way to understand it would be a graphic with probability circles for a certain amount of liquid equiv precip - say 1" and probabilities, .5" and probabilities and so on. Same then for snow accumulations. Last storm somebody posted a link to something similar. Do any models / forecasters have graphics like that?

Posted by: biketraveller22 | January 23, 2011 11:43 AM | Report abuse

I love u GFS. I think it's time to do my snow disco dance.

Posted by: weatherfreak1994 | January 23, 2011 11:44 AM | Report abuse

Thanks to everyone at CWG for all of these reports. I found you two years ago and have learned a tremendous amount from you since then. Brian - great post there about all the different levels. I never really understood those maps before, but now I have a better grasp of what they mean.

Thanks!

Posted by: jackowen | January 23, 2011 11:49 AM | Report abuse

im not sure why people are loving the GFS for snow, if anything the near miss seems more likely than snow. Even if the next GFS run trends west it has to trend west a couple hundred miles to give dc and especially west of DC snow. If anything, its better to root against the GFS.

Until this thing is actually down south, im not believing anything. Im sticking with the trend that these storms have taken all year. This time tomorrow the euro and gfs will be in closer agreement as to the track of the storm. This time tuesday we will still have no clue exactly what we are going to get LOL. Sad but i believe to be true.

Posted by: KRUZ | January 23, 2011 11:51 AM | Report abuse

bay city rollers Saturday night LOVE THAT SONG:)

Posted by: weatherfreak1994 | January 23, 2011 11:52 AM | Report abuse

@KRUZ. If taken literally, the GFS would already give us 3-6 inches of pure snow. If it shifted just a tad west, we woul get over a foot. http://www.americanwx.com/bb/uploads/monthly_01_2011/post-506-0-07538900-1295798912.gif

Posted by: samdman95 | January 23, 2011 11:55 AM | Report abuse

@samdman95

But something has to be said of the 06Z run?...

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/06/images/gfs_slp_096m.gif

We cant just write it off can we?

Posted by: KRUZ | January 23, 2011 11:59 AM | Report abuse

@biketravel1er22

The GFS ensemble has probability of greater than 0.25, 0.5, and 1 inch of liquid precipitation.

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gens/00/model_m.shtml

That's a link to the 00Z run. The 12Z run should be coming up shortly.

Posted by: Steve-wxtalkwordpresscom | January 23, 2011 12:01 PM | Report abuse

Still haven't seen anything indicating an all snow storm, expecting the usual snow/sleet/rain that most of these storms bring us. Of course, areas 2 the W will get more frozen prec. It still looks like 2 much warm air will b pulled in aloft. It would really b great if we could keep H pressure 2 the N 2 allow more cold air 2 filter into they system. Ideally the H should b centered over the Hudson Bay area.
Go Steelers, 6.5 hrs 2 kickoff.

Posted by: VaTechBob | January 23, 2011 12:06 PM | Report abuse

@KRUZ

We have to assume that a later run of the GFS has more information inputted and therefore less chaos. Yes, it is by no means deterministic, obviously, but it should be a "better run."

That being said it's not about what the run projects per say, but the trend. The trend from the last run was about a 150 miles shift North, a change from zippo to a couple inches of snow or some rain.

That being said, trends on operational runs are pretty obsolete when chaos is running this rampant, something that has even bitten me in the behind over the last couple days on what I've prognosticated about this event.

See how confusing this is? And I don't even understand much of the scientific side. To quote someone from earlier, this is a nightmare for the mets.

Posted by: bbirnbau | January 23, 2011 12:07 PM | Report abuse

VaTechBob,

Completely true. I was wondering about the High pressure beginning to drift across S Canada.

Funny how at the beginnings of tracking this storm we were worried about another HP system drifting off the NE/NS coast, then we gave up on it as being far to OTS before the storm arrived. Now I see a HP system drifting across southern Canada that may bring in some ample cold air to support frozen precip.

But there's nothing to blocking the High. Wondering if it's possible for a drifting High to "be in the right position" for the duration of a storm in order to supply necessary cold air.

Posted by: bbirnbau | January 23, 2011 12:11 PM | Report abuse

Today is a day to fire up the fireplace and sit on the couch and watch football.

Just waiting for the snow storm to come. Im calling for 6-10 inches in the D.C. metro area.

There's no way we will get rain. It's too cold and these freezing temps aren't going anywhere anytime soon.

Posted by: SNOWLUVER | January 23, 2011 12:21 PM | Report abuse

we've probably got to be careful converting qpf to snow inches. generally a 1:10 ratio, this storm could easily be really wet snow. 1:8 or 1:5?

cwg, wxperts,
what is the lowest, wettest snow ratio you can have, or that you've seen from just snow? not where rain falls on top of snow, but just snow?

Posted by: walter-in-fallschurch | January 23, 2011 12:23 PM | Report abuse

Wow ppl here are already throwing out totals, even with all thats happened over this past winter thus far?...

Well then I guess I'll throw out my totals prediction: BUST

Posted by: KRUZ | January 23, 2011 12:30 PM | Report abuse

Hello everyone, Wes Junker will be posting an update for you on the blog here between 130pm-2pm. FYI!

Posted by: Camden-CapitalWeatherGang | January 23, 2011 12:50 PM | Report abuse

NWS just downgraded western Loudoun to 20% chance of precipitation on Tuesday night. :-(

Posted by: celt1 | January 23, 2011 12:53 PM | Report abuse

@KRUZ -

I like your prediction. I'm gonna go with that one.

Posted by: ThinkSpring | January 23, 2011 12:58 PM | Report abuse

@celt, the storm is more likely to happen on wednesday. If anything, with the 12z suite of model runs, the chance of precip has increased

Posted by: samdman95 | January 23, 2011 12:59 PM | Report abuse

@walter-in-fallschurch: Regarding the lowest snow ratios, I remember a snowstorm when I lived in Alexandria that snowed moderately for the entire event but the snow never stuck to the ground. Surface temperatures were about 35 degrees. So, I suppose the ratio for that snowstorm was 1:0.

Posted by: Kevin-CapitalWeatherGang | January 23, 2011 1:03 PM | Report abuse

RAIN RAIN RAIN RAIN RAIN! Just sayin' (or wishin'; Vegas bound on Wednesday)!!!

Posted by: Islandernole | January 23, 2011 1:05 PM | Report abuse

Lol yeah. Weather.com tells me there will be rain/snow/wind on wednesday. No sleet/hail/ice?

Posted by: MVPlaya8120 | January 23, 2011 1:07 PM | Report abuse

The GFS is very encouraging in that it took a westward shift. I think that it will shift further west than in the 18z run, but you never know. It'll be interesting to see what the Euro says... I'm looking forward to the upcoming analysis by Wes.

KRUZ, I know you don't like snow, and to have a good reason not to. But don't you think we snow-lovers deserve at least one good snowstorm this winter??

btw, the current reading on my deck here in NE Loudoun is 25.5°F. If only it could stay that cold for the upcoming storm...

Posted by: BobMiller2 | January 23, 2011 1:10 PM | Report abuse

@Camden: Wes Junker will be posting an update for you on the blog here between 130pm-2pm.

*yay*

@Kruz: as much as I love snow, I have to kinda lean your way. hoping that I'm wrong however!!

Posted by: kygurl94 | January 23, 2011 1:29 PM | Report abuse

@BobMiller2

Yeah you snow lovers deserve one good snow this year but I would also question dont us snow haters deserve a close to no snow winter this year after going through the SNOW LAST WINTER? ;)

But you know Bob, how about I meet you in the middle. I'll root for a snow storm towards the end of the winter season, say March 1st, when there is maybe some warmth in sight. See maybe a foot of snow march 1st then spring comes in. So you get your snow and then shortly after I get my warm up and more importantly, no more snow!

Posted by: KRUZ | January 23, 2011 1:29 PM | Report abuse

KRUZ - That seems like a very fair compromise.
I will await with interest your forced snow enthusiasm in early March :-)

Posted by: FIREDRAGON47 | January 23, 2011 1:36 PM | Report abuse

@Jason-cwg re: 653am

ha, not exactly setting a high bar, but your probably right..

Posted by: jp142 | January 23, 2011 1:36 PM | Report abuse

spgass: That is funny with the nutshell coffin for stinkbugs. I saw it at your website a day or two ago. But putting them in coffins means touching them. Ych!

Eric, my house loves dry, whatever the season. The monsoon of 2009 caused mold which I fortunately was able to remediate. As for winter precip damage--well, I haven't had a roof or deck collapse from snow weight but I've had to replace a north-facing skylight when ice/snow just sat there forever and cracked it, and Snowmaggedon clogged gutters and drains so that melt ran down on the wrong side of the cedar siding--what a headache.

Posted by: tinkerbelle | January 23, 2011 1:38 PM | Report abuse

CWG-

How hard has it been to forecast temperatures mid-range, say 5 days out this season?

If forecasts were for a more moderate winter, well, they were way off.

When are we going to get back on track to normal temperatures?

Posted by: moo1 | January 23, 2011 1:44 PM | Report abuse

@Wes Junker

Wes...can you please comment on the 12Z JMA when you post. Particularly the 96 hour mark. WOW...just WOW! That is a log of precip!

Posted by: DLO1975 | January 23, 2011 1:47 PM | Report abuse

Still hoping this Tuesday night junk "busts" or goes out to sea, so my swing dance doesn't get "hit"...as I previously posted, it's a new band...first time at the Clarendon Ballroom.

Sure wish "much-unneeded rain" would QUIT scheduling all these wintry-mess events for dance nights--I have dances both Tuesday and Friday nights this coming week. Thus far the Friday night event looks okay.

Posted by: Bombo47jea | January 23, 2011 1:54 PM | Report abuse

Still hoping this Tuesday night junk "busts" or goes out to sea, so my swing dance doesn't get "hit"...as I previously posted, it's a new band...first time at the Clarendon Ballroom.

Sure wish "much-unneeded rain" would QUIT scheduling all these wintry-mess events for dance nights--I have dances both Tuesday and Friday nights this coming week. Thus far the Friday night event looks okay.

Posted by: Bombo47jea | January 23, 2011 1:54 PM | Report abuse

Still hoping this Tuesday night junk "busts" or goes out to sea, so my swing dance doesn't get "hit"...as I previously posted, it's a new band...first time at the Clarendon Ballroom.

Sure wish "much-unneeded rain" would QUIT scheduling all these wintry-mess events for dance nights--I have dances both Tuesday and Friday nights this coming week. Thus far the Friday night event looks okay.

Posted by: Bombo47jea | January 23, 2011 1:55 PM | Report abuse

After an entire winter of disagreement on seemingly every winter storm, even with less than 24 hours till storm-time, the GFS and NAM are really close with their 12Z runs all the way out to 84 hours

Posted by: 4seamed | January 23, 2011 1:55 PM | Report abuse

Also wondering...why is my comment triply-posting???

PLEASE FEEL FREE TO DELETE THE DUPLICATE POSTS!!!

Posted by: Bombo47jea | January 23, 2011 1:58 PM | Report abuse

Wes' post is up.

Posted by: Ian-CapitalWeatherGang | January 23, 2011 2:01 PM | Report abuse

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