Network News

X My Profile
View More Activity
The new Washington
Post Weather website
Jump to CWG's
Latest Full Forecast
Outside now? Radar, temps
and more: Weather Wall
Follow us on Twitter (@capitalweather) and become a fan on Facebook
Posted at 5:00 AM ET, 12/24/2010

Forecast: Continued wintry. Weekend snow?

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

 

Winds slacken, but gusts around 30 mph negate the minimal warmth of mid-winter sun. At least it's Christmas Eve?
 
Get the 'Digit' on Twitter

EXPRESS FORECAST

Today: Partly sunny, breezy. Mid-30s to around 40. | Tonight: Mostly cloudy. Low-to-mid 20s. | Tomorrow: Mostly cloudy. Late-day snow showers? Mid-30s. | Sunday: Overcast, becoming windy. Chance of snow. 30s. | A Look Ahead | Get Express Forecast by E-mail

FORECAST IN DETAIL

Cold temperatures in the 30s, windy periods, and quite cloudy conditions are common characteristics of our weather through this weekend. Slight chances for snow appear from Saturday afternoon through Monday morning, with confidence still not high on even getting anything at all. At least Christmas Eve and Christmas Day travelers will have very few, if any, impacts to their schedules, at least as far as weather goes. We'll keep watching the latest guidance for you though, and promise to give you the latest as we know & interpret it!

Snow Potential Index: 4 (↓) - Odds of a big weekend snow are down, but a measurable dose of snow still seems remotely possible. Someone to the east and northeast could get more?

 
The SPI is a daily assessment of snow potential 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 (Friday): Chilled temperatures in the mid-30s to near 40 feel mighty brisk, then you factor in northwest winds sustained as high as around 15 mph with gusts around 30 mph! I want full-on winter gear with me at all times today: scarf, hat, ear muffs, heavy coat, double socks. All of it! Luckily for shoppers and travelers alike, we see some sunshine and have no weather disturbances for our Christmas Eve. Confidence: Medium

Tonight: Clouds creep into the region slowly but surely. Temperatures still get pretty cold, but they're somewhat more uniform than usual -- in the low-to-mid 20s. Northwest winds calm just a bit -- not as gusty -- but still in the 10-15 mph range. That is enough to keep you bundled up tightly, I'd say! Confidence: Medium-High

How are our chances for snow this weekend? Keep reading...

Christmas (Saturday): Mostly gray and still colder than average, with high temperatures making it to mainly the mid-30s. If any light snow -- mostly snow showers -- arrive in the afternoon, temperatures may head toward freezing. Northwest winds are still around, but lighter -- only around 5-10 mph. Chance of snow is not too great, around 30%. Confidence: Low-Medium

Christmas night: Cloudy, cold, with a continued 30% chance of light snow, or snow showers. Only a slight northwest breeze, but it's cold even without it. Low temperatures slowly dip then hover in the mid-20s throughout most of the region. Confidence: Low

Sunday: As of now, the storm system we have been watching mainly impacts those north and east of the area, but still brings a slight risk of snow here. High temperatures could range from the low-to-mid 30s to the upper 30s depending on storm impacts -- higher temperatures if it doesn't snow at all or very much. There's about a 30% chance of accumulating snow. A lot is still up in the air even though we're running out of forecast time. As the storm passes, northwest winds pick up again, in the 15-25 mph range. Confidence: Low

A LOOK AHEAD

On Sunday night a slight chance of snow continues into the evening but that chance diminishes thereafter. Low temperatures head into the mid 20s (suburbs) to nearer 30 downtown. Skies are variable, but mostly cloudy. Confidence: Low

Monday looks like one of those cold, fairly cloudy and windy days we've seen so many of this December. Cold air is reinforced at least temporarily with potentially strong winds out of the northwest. High temperatures struggle to get much past freezing -- perhaps as high as the mid-30s. Confidence: Low-Medium

Tuesday could see our first moderate dose of sunshine in a while. Highs look to get above freezing, into the mid-to-upper 30s. But this time of year, I tend to think clouds will always win-out when competing with the weak sun angle. Breezes may continue, but they should be lighter than Monday. Confidence: Low-Medium

By Camden Walker  | December 24, 2010; 5:00 AM ET
Categories:  Forecasts  
Save & Share:  Send E-mail   Facebook   Twitter   Digg   Yahoo Buzz   Del.icio.us   StumbleUpon   Technorati   Google Buzz   Previous: PM Update: Winds to reluctantly relent
Next: A look back at big Christmas snows in D.C.

Comments

NW exurbs looking at 40% chance of white Christmas from the system to our west. It'd be interesting if that turned out to be the snow-maker for the region.

Well, the family is all here and due to that blasting wind we've long since battened down the hatches, so I'm ready. It's a gorgeous morning in the country, with moonset and sunrise together in a clear cold sky.

Posted by: tinkerbelle | December 24, 2010 6:49 AM | Report abuse

*pop*
That was the sound of Camden putting the final pin in my White Xmas dream bubble.

Posted by: FIREDRAGON47 | December 24, 2010 7:19 AM | Report abuse

Ya, for a blog that spent the better part of a few days hyping a white Christmas, don't you think the SLCB number should be a 2 or a 1 at this point?

Sometimes a model is just a model. It is not going to snow even a trace amount in the western suburbs until after New Year's. Book it.

Posted by: doczoidberg | December 24, 2010 7:47 AM | Report abuse

So how far north and east is "north and east"? I am currently living in Crownsville MD and working in NE DC. I have to work every day (for the forseeable future ... yes I'm cracking! no, it's OK, it's a transition). OK, so should I plan to be ready to stay in town any of these nights? IOW, is Crownsville significantly more likely to get snow than DC?

Thanks

Posted by: ChickenLady | December 24, 2010 8:14 AM | Report abuse

I think 'Northeast of DC' is codeword for 'Cape Cod'.

Posted by: jpl1019 | December 24, 2010 8:53 AM | Report abuse

Despite the ever decreasing chance of snow eveyone have a merry Christmas.

Posted by: marathoner | December 24, 2010 9:00 AM | Report abuse

I don’t think that CWG hypes the weather. I think we snow lovers have to take a look at ourselves as the culprits. We voted for wanting even more snow than last year, we say, please, please, tell us it’s going to snow and we see “30% of snow” and act like it’s a 70% chance.

They lay out the models and factors, and give us probabilities. I wanted snow real bad too, but I don’t blame CWG for hyping. It's more us hoping.


Posted by: jaybird926 | December 24, 2010 9:04 AM | Report abuse

While the models are giving us little, if any snow this weekend, the upper system looks stronger as depicted by the 6Z GFS. I think it's still too early to write this off.

Posted by: frontieradjust | December 24, 2010 9:08 AM | Report abuse

One of the things I love about CWG is they don't hype, they are always balanced. They tell us straight up how likely the chances of snow (or any other weather) are and why.

Posted by: SubRosa2 | December 24, 2010 9:12 AM | Report abuse

I don't think they hype either. I've decided that it was all my fault that the storm fell apart for us. On Wednesday night I went to the grocery store to shop for Christmas dinner, and I decided to stock up on some other items just in case we were snowed in for a few days. I jinxed it!

Posted by: weatherwatcher1 | December 24, 2010 9:18 AM | Report abuse

As I am a die hard Redskins fan, and snow fan, this dissapointment is a familiar feeling. Oh well, I will keep coming back and hoping (just like I do with my Skins). Thank you, CWG, for the most excellent blog, expert analysis, and NO HYPE. Happy Holidays to everyone!!

Posted by: kathyb39 | December 24, 2010 9:24 AM | Report abuse

Seen some posts recently regarding "off" model runs. (i.e. the 6Z and 18Z runs).

My memory is that those runs aren't viewed as credible as the 0Z and 12Z runs. Why is that? Can someone refresh my memory?

Posted by: ThinkSpring | December 24, 2010 9:37 AM | Report abuse

Hope CWG will keep us updated with this weekend storm throughout Christmas if they get a minute or two in between family time to do so :)

Im seeing a warm up coming late month up into the 40s! Just wondering what the thoughts are on that new years storm on the GFS are. Right now I see the 540 line is well west of us. I know the storm is far out, but it has been there for quite a while now, just wondering what any of your thoughts are on it up to this point. Rain event, mix or snow?

Merry Christmas and/or Happy Holidays to the entire CWG!!! Thanks for all you do.

Posted by: KRUZ | December 24, 2010 9:39 AM | Report abuse

The 12zNAM is giving us a late dandruffy white Xmas :-D

Posted by: dustinmfox1 | December 24, 2010 9:55 AM | Report abuse

The NAM at 12Z for the first time is showing a little snow for DC with the coastal storm. It keeps looking better at 500 mb.

Not a big storm yet, but at least it's trending the right way.

Posted by: frontieradjust | December 24, 2010 10:41 AM | Report abuse

@kathyb39

"As I am a die hard Redskins fan, and snow fan, this disappointment is a familiar feeling."


Amen sister.

Posted by: Vingold | December 24, 2010 10:47 AM | Report abuse

Bastardi is not throwing in the towel on this. He's not alone, as a few local meteorologists are also saying let's not give up on this so fast. For those that are interested in Bastardi's thoughts, see below. For those that are not fans of his, please skip this post.

FRIDAY 9 AM - ITS NOT OVER...YET
The complex Christmas weekend snowstorm is underway with part one. This will feature the large area of snow over the plains moving eastward and weakening with time. Again I dont have moveable type, but I am going to give you some links to look at so you can see what I am talking about.. The good people at Harris Weathercaster have the JMA model out to 72 hours for the 00z run and it best illustrates my idea

So if you can open another browser and copy links, you will see what I am saying

The 48 hour surface map http://grib2.com/jma/CONUS_JMA_1000-500_SLPTHKPRP_48HR.gif

We see the large area of snow, mainly light, north of the pinkish line but snow deep into the southland, a major rare event on Christmas day. Notice the enhancement of snow near Chicago

At 500 mb http://grib2.com/jma/CONUS_JMA_500_GPHTMPVORT_48HR.gif

The trough is digging right into the slot that I love so much for mid and north atlantic snowstorms. In fact, I could not have forecasted the upper pattern any better for all of this the past 3 weeks, including last weeks miss. The upper features are heading right to what I envisioned, its that simple, but the surface map is the problem. Last weeks storm had the low develop too far southeast relative to the trough. To some extent, this is the problem here. But is the system going to develop that far out to sea. That is a big question

In some way this is similar to a late January 2000 storm that shocked many on the east coast ( see my blog from two days before that, if we have it archived) that lead Congress to get mad because a 10 inch storm hit after a forecast for flurries. That too was an error of where the storm was developing in relation to a perfect upper pattern. Folks upper lows moving from Kentucky to Nantucket and deepening dont normally dump no snow in the mid atlantic states. In any case off the Harris site, a look at the 72 hour JMA 500 mb.

http://grib2.com/jma/CONUS_JMA_500_GPHTMPVORT_72HR.gif

and the surface map: http://grib2.com/jma/CONUS_JMA_1000-500_SLPTHKPRP_72HR.gif

While this is fairly far west and of course with the upper pattern snow would expand northwest and this could be a monster from NYC northeast especially ( definition of monster at least 10 inches of snow with gusts over 40 mph) However even this, given the 500 mb looks to far east as its more likely to be tucked in over the gulf stream.

Point is, its not over yet. However in the spirit of the season, and the fact that many, and they have absolutely valid reasons for it, dont believe this can come close enough to become a monster, I have a song for the season..

Posted by: DLO1975 | December 24, 2010 10:54 AM | Report abuse

The 54 hour GFS surface map is certainly interesting...isn't it?!

Posted by: DLO1975 | December 24, 2010 11:01 AM | Report abuse

@DLO1975
yeah...I remember that storm in January of 2000. It was my senior year of high school. I remember being disappointed by the forecast of flurries. But then between 8 or 9 or so, I noticed that the large area of precip over eastern Virginia and NC was taking a course directly north and even NNW- directly for us. The TV mets quickly updated their forecasts at the 10/11pm newscasts, but I'm sure many were pretty surprised to find all that snow the next morning!! So my question to CWG...does the set-up with this storm indeed resemble the set-up we had with that particular storm in 12/00 that JB makes reference to?? Thanks.

Posted by: BH99 | December 24, 2010 11:07 AM | Report abuse

Whoa, baby. How about that 12Z GFS?!

Posted by: bdeco | December 24, 2010 11:08 AM | Report abuse

FIREDRAGON47 - sorry about that, but I guess it is very diminished now... thank you for the sound effect, I suppose :)

doczoidberg - too many uncertainties and because weather models are mathematical, numbers have to be averaged and tempered up or down in incremental fashion. Would not be mathematically sound to completely write off the snow at this point.

Posted by: Camden-CapitalWeatherGang | December 24, 2010 11:12 AM | Report abuse

12Z GFS looks REALLY interesting at 54 and 60 hours! Could this actually trend far enough west to get us into some decent accumulating snow after all?

Posted by: DLO1975 | December 24, 2010 11:13 AM | Report abuse

These models being all over the place and so inconsistent is becoming very aggravating. I need to make travel plans for the weekend and can't seem to get a handle on exactly what is going to happen 24-48 hours out.

Posted by: ThinkSpring | December 24, 2010 11:13 AM | Report abuse

CWG guys...can we get your thoughts on the 12Z GFS run. Are we being foolishly hopeful looking at the 60 hour mark?

Posted by: DLO1975 | December 24, 2010 11:20 AM | Report abuse

ChickenLady - I don't think you need to alter your plans. If anything falls, it will be an amount which should only require leaving early... allowing for extra time.. no need to sleep over.

As far as models go, I am sure this storm will continue to be chaotic within the mathematical systems known as weather models. We can get excited about one set of the latest models, but we can reference every other weather model run before it... the storm is not easily grasped by the models. And we will likely see on-again-off-again chances for snow in our area. CWG hasn't written it off yet, but chances for high amounts of snow for long periods of time is increasingly low. Of course we will continue to watch it, but I don't want everyone looking at one model run in isolation. Please see the ensemble models that more properly represent probabilities--these probabilities for snow do match our current forecast of around 30% chance, for snow on the lighter end of the spectrum. If there are any changes, we will create a new post!

Posted by: Camden-CapitalWeatherGang | December 24, 2010 11:26 AM | Report abuse

Thanks, Camden. That put things in perspective for me.

Posted by: ThinkSpring | December 24, 2010 11:30 AM | Report abuse

ThinkSpring - it is definitely a frustrating scenario, but we will keep watching it!

Everyone travel safely today -happy holidays!

Posted by: Camden-CapitalWeatherGang | December 24, 2010 12:06 PM | Report abuse

MODEL DIAGNOSTIC DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
1159 AM EST FRI DEC 24 2010

VALID DEC 24/1200 UTC THRU DEC 28/0000 UTC


...SEE NOUS42 KWNO ADMNFD FOR THE STATUS OF THE UPPER AIR
INGEST...

12Z NAM/GFS EVALUATION INCLUDING PRELIMINARY PREFERENCES

...SPLIT SHORTWAVE TROUGHS EXTENDING OVER THE PLAINS/MIDWEST...
...LOW PRESSURE FORMING ALONG THE EAST COAST THROUGH MONDAY...

PREFERENCE: EQUAL BLEND OF THE 06Z GFS/00Z ECMWF OR THE ENSEMBLE
MEANS

INITIALIZATION ERRORS IN NUMEROUS DIAGNOSTIC
QUANTITIES...INCLUDING HEIGHT/VORTICITY FIELDS/RH...ARE EVIDENT IN
BOTH THE 12Z NAM/GFS WITH SMALL BUT LIKELY SIGNIFICANT SHORTWAVE
TROUGHS OVER SOUTH DAKOTA/NEBRASKA ALONG WITH
SASKATCHEWAN/MANITOBA...WITH THESE AREAS ALSO NOT PARTICULARLY
RESOLVED OR PREDICTED WELL BY THE 00Z ECMWF. THUS...THE SPECIFIC
PREDICTIONS BY ALL DETERMINISTIC GUIDANCE ARE IN QUESTION...WITH
THE RECOMMENDATION TO FOLLOW CONTINUITY...WITH THE FINAL OUTCOME
MOST BELIEVED TO LIE BETWEEN THE 06Z GFS AND 00Z ECMWF...WITH ALL
ENSEMBLE GUIDANCE INCLUDING THE SREF MEAN/GEFS MEAN/ECMWF ENSEMBLE
MEAN ALSO CONSIDERED USEFUL TO ADDRESS THE CONTINUED UNCERTAINTY.
THIS APPROACH DISREGARDS THE SUBSTANTIALLY DEEPER AND WESTWARD
SHIFT OF THE 12Z GFS REGARDING THE POWERFUL LOW TRACKING UP THE
EASTERN SEABOARD...AND TO A LESSER EXTENT THE 12Z NAM WHICH LIES
NEAR THE FAST EDGE OF THE GUIDANCE WITH THE DEVELOPING LOW.

...HIGH AMPLITUDE SHORTWAVE TROUGH ENTERING THE WEST SATURDAY
NIGHT/SUNDAY...

PREFERENCE: NAM OR 00Z ECMWF ACROSS CALIFORNIA AND THE SOUTHWEST

THE GFS HAS TRENDED SLOWER WITH SOUTHERN PORTIONS OF THE TROUGH
ENTERING CALIFORNIA AND THE SOUTHWEST SATURDAY NIGHT AND
SUNDAY...BUT IS STILL FASTER THAN THE AGREEING NAM/00Z
ECMWF...WHILE THE GFS IS ONLY SLIGHTLY FASTER WITH NORTHERN
PORTIONS OF THE TROUGH. GIVEN GFS TRENDS AND SUPPORT FROM THE 00Z
UKMET/CANADIAN...THE PREFERENCE ACROSS THE SOUTHWEST IS FOR THE
NAM OR 00Z ECMWF.

...LOW PRESSURE NEARING THE PACIFIC NORTHWEST COAST LATE MONDAY...

PREFERENCE: 2/3 NAM OR 00Z ECMWF TO 1/3 GFS

THE NAM/00Z ECMWF ARE IN RELATIVELY GOOD AGREEMENT WITH A SURFACE
LOW AND ACCOMPANYING LEADING EDGE OF ITS FRONTAL SYSTEM
APPROACHING THE COAST JUST WEST OF PORTLAND BY 00Z TUE...WHILE THE
12Z GFS IS ABOUT 200 NM FARTHER SOUTH AT THE SAME TIME. WHILE
SOLUTION SPREAD IS QUITE LARGE AT THIS TIME FRAME...
RECOMMEND LEANING TOWARD THE MORE NORTHERN SOLUTION OF THE NAM/00Z
ECMWF.

...MODEL TREND GRAPHICS AT
WWW.HPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML...
...500MB FORECASTS AT WWW.HPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML...

Posted by: KRUZ | December 24, 2010 12:39 PM | Report abuse

Forget about the 60 hour mark...I'd like to hear about the 60 Degree mark...for the end of next week. How about it CWG? And happy holidays to you guys. Best weather blog on the net.

Posted by: dhb2 | December 24, 2010 12:39 PM | Report abuse

The Bombo snow-threat index falss back below 5 to 3.5

...However even a deepening storm that far out east over the ocean is NOT a snowstorm! With the ocean still having a sea-surface temperature around 8-12 Celsius and the air immediately above the ocean at a similar temp--we're talking 45 degrees Fahrenheit or so for 2000 feet or so--all that "abundant moisture" is gonna fall as a cold wind-driven RAIN! For excitement you might add a few lightning strokes so embedded thunderstorms are a risk near the storm center! Just rent a cruise ship from Carnival or Royal Caribbean and sail out a couple hundred miles or so from Baltimore to enjoy the "great winter storm". Bet you won't see much snow, but the wind and waves will make you mighty seasick. The only snow at our latitude may be a rather narrow band on the north and west fringe of this system...gotta get north to New England before there's enough cold air for the 16-plus inches they were forecasting southeast of Richmond a few days back.

Even the temperature here is 39 degrees, not the 25 degrees at 12:50 PM we need for a major accumulating-snow event around here. Warm air advection seems much too possible if the "abundant moisture" were to make it this far north and west. Granted it DOES feel cold, but that's the wind-chill!

One further reality check: They seem to be bracing for a good accumulation around Hickory, North Carolina, but Hickory and nearby areas in the Blue Ridge are at considerable elevation. Down near Wilmington and Myrtle Beach, they are looking at cold rain and even much of interior South Carolina has been notified to prepare for a RAIN EVENT. A couple of days ago everyone in the interior Deep South was eagerly anticipating a white Christmas with snow on the magnolias. Looks like there just isn't quite enough Arctic air in this system anymore.

Posted by: Bombo47jea | December 24, 2010 12:41 PM | Report abuse

So NWS is basically sayint there were some problems with the 12z runs?... Can anyone from CWG make some better sense of this for me :)

Posted by: KRUZ | December 24, 2010 12:42 PM | Report abuse

I think some r starting 2 wishcast. While there is a chance of a decent snow, the odds r very low. Then again, never say never with regards 2 weather.
Expecting warmer temps for Jan.


Posted by: VaTechBob | December 24, 2010 12:42 PM | Report abuse

Just wanted to say Happy Holidays to all! I love the CWG! It's the first place I check in the morning! Although I really wanted snow this weekend, I have been so happy to see all the discussion of the models and the balanced analysis. Thanks - you all are the best!

Posted by: soleil2000 | December 24, 2010 12:51 PM | Report abuse

Hey CWG--I've seen a few mentions of more snow on the eastern shore, and accuweather is predicting about 3" in Rehoboth. We're driving there on Sunday--any thoughts on snow on the beaches and when it might happen? Thanks for a great blog! And happy holidays to everyone!

Posted by: beachy3 | December 24, 2010 12:53 PM | Report abuse

dhb2 - happy holidays to you too. Yes I would also like a brief respite from the cold. One, just one, 60 degree day sounds nice ;) Going to be not-60 for at least two weeks it appears though. (Obviously low confidence after 6 day forecasts, but I see atmospheric signs we won't warm substantially anytime in the near future)

KRUZ - yes, your interpretation is essentially correct. Initial information from the global system of radiosondes (weather balloons) and weather station data was either not entered into the system correctly, or some algorithmic error occurred just after the model was initialized. Output got screwy, apparently. I am glad NCEP caught the error. Yet one more aspect to the weather models "keeping us on our toes" today AND also evidence NOT to read weather model output in isolation or without considerable interpretation of ALL information (past and present) :) sorry about my run-on sentence!

Posted by: Camden-CapitalWeatherGang | December 24, 2010 1:43 PM | Report abuse

VaTechBob - I wish I had an "agree" button below your comment ;-)

soleil2000 - thanks for reading us! Appreciate your feedback. Have a safe, enjoyable holiday time

beachy3 - timing for [if] any snow would be Sunday late afternoon through early Monday morning in Rehoboth... 3" could be a bit high. But safe to plan for that much, rather than be surprised. As long as your comfortable driving in a slowly accumulating 3 inches, I'd say don't worry about it too much. Salt trucks should be able to keep main roads clear, too. I hope that helps? Sorry to repeat that this is a low confidence forecast, but I am giving you my best median..educated interpretive..estimate! :)

Posted by: Camden-CapitalWeatherGang | December 24, 2010 1:59 PM | Report abuse

The comments to this entry are closed.

 
 
RSS Feed
Subscribe to The Post

© 2012 The Washington Post Company