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Posted at 5:00 AM ET, 01/10/2008

Forecast: Unsettled Through Next 48 Hours

By Josh Larson

Noticeably cooler by Sunday

A series of cold fronts -- one that moved through yesterday and another passing by today -- will provide us with up-and-down temperatures and periods of showers and rain today into early Friday. Thereafter, drier weather and cooler temperatures are in store for Saturday, while seasonably cold conditions return on Sunday and into the start of next week.

TODAY

Partly sunny a.m., cloudy and showery p.m., low 50s. Plan on a partly sunny morning, but then increasing clouds and becoming overcast in the afternoon. Highs in the low 50s will be some 10-15 degrees cooler than yesterday. Showers are likely to develop during the afternoon, and may increase in coverage and intensity by early evening. Periods of rain will linger into the overnight hours, with rather mild low temperatures in the mid 40s in most spots.


A colorful sunset over downtown D.C. captured Tuesday evening by Capital Weather Gang photographer Ian Livingston.

TOMORROW

Morning showers, near 60. The day will likely start off with overcast skies and occasional showers, which may linger through the lunchtime hour. In the afternoon, skies will remain mostly cloudy, but some peaks of sun will probably allow high temperatures to hit the 60 degree mark. Partial clearing and a touch cooler Friday night, with lows from the mid 30s in places like Herndon and Gaithersburg and near 40 downtown.

THE WEEKEND

Turning cooler again, mid 40s to low 50s. Expect more clouds than sun on Saturday, though with dry weather, and highs within a few degrees of 50. Saturday night will feature partly to mostly cloudy skies with overnight lows dropping to near freezing in suburban areas like Damascus and Reston, and in the mid to upper 30s downtown.

Sunday will likely feature more clouds than sun with the slight chance (about 20% as of now) of rain showers or wet snow courtesy of a coastal area of low pressure. At the moment, indications are the coastal low may stay too far offshore to have a significant impact on the area. Expect highs in the mid 40s with cooler overnight lows ranging from 30-35 and a slight chance of continued wet or wintry precipitation.

A LOOK AHEAD

Depending on what happens with the possible coastal low near our region, the forecast for Monday is an uncertain one. We'll call for mostly cloudy skies with a slight chance of rain or wet snow and highs near 40. Overnight lows will drop to the upper 20s to low 30s.

The forecast for Tuesday is a more confident one: Expect mostly sunny skies and seasonably cold high temperatures ranging from the upper 30s to low 40s. Overnight lows will drop, once again, to the upper 20s to low 30s in most spots.

Plan for partly to mostly sunny skies on Wednesday, with temperatures a notch or two warmer and most likely in the low to mid 40s for highs. Cooler overnight lows will drop to the mid 20s across the outlying suburbs to near 30 downtown.

By Josh Larson  | January 10, 2008; 5:00 AM ET
Categories:  Forecasts  
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Comments

Morning check and it is not looking good for a snow event for this weekend.

Off to the office where I will check in from time to time this afternoon.

Posted by: Greg | January 10, 2008 6:07 AM | Report abuse

Greg,

Just wondering what you are basing that off of. The GFS at 6z has this much farther west and 850mb temps look good (but of course that doesn't always mean snow). ECMWF also trended EAST giving a better look to it. Just wondering how you came to that conclusion.

Posted by: Kenny | January 10, 2008 6:45 AM | Report abuse

Judging from the model shifts late yesterday and this morning, I think it's looking much better for a winter storm of some sort Sunday night and Monday. My fear is that it may turn out to be mostly rain, given the way that this winter has gone.

Posted by: Kevin | January 10, 2008 7:52 AM | Report abuse

Kenny:
You are exactly right. The compromise that I suggested between the GFS and EURO last eve. has occurred overnight. The GFS now bombs a 996 low near the Va. capes by 1 a.m. Monday with heavy snow to the tune of 5-10 inches for the duration, over much of the area especially north and west of DC. Surface temps. would be marginal in the DC area. During much of the storm the 32F line remains a little north and west of the capital.

But remember, this is only one run of the GFS! The GGEM, JMA and DGEX are NOT bullish on this potential.

Posted by: Augusta Jim | January 10, 2008 8:04 AM | Report abuse

Agree for the most part Augusta Jim, Euro has been more consistant, GFS seems to be trending towards it. If those two showed this setup 24 hours away, I'd be psyched....72 hours and ALOT more runs to go ;)

Posted by: Mike from the Blue Ridge | January 10, 2008 8:55 AM | Report abuse

Agree for the most part Augusta Jim, Euro has been more consistant, GFS seems to be trending towards it. If those two showed this setup 24 hours away, I'd be psyched....72 hours and ALOT more runs to go ;)

Posted by: Mike from the Blue Ridge | January 10, 2008 8:56 AM | Report abuse

Josh, can you really say "will provide us" when you're reporting from Boulder, CO?

Posted by: Kalorama Park | January 10, 2008 9:10 AM | Report abuse

Im suprised that we had such a westerd shift in GFS.Good News...We just need cold temps.I dont know much about artict highs. Is there one building in to give us a better shot for colder air...Previous storms, I can recall the highs were weak..

Posted by: skinsfn | January 10, 2008 9:29 AM | Report abuse

Sorry folks. My grammer isn't the best when I rush..I will make a point to proofread this point forward.

Posted by: skinsfn | January 10, 2008 9:31 AM | Report abuse

Morning everyone ... for those clamoring for an at-a-glance type forecast -- we are working on it. May be a few weeks, but please bear with us and please keep checking back. Don't forget about us!

Posted by: Dan, Capital Weather Gang | January 10, 2008 9:42 AM | Report abuse

Great news Dan! As forgetting about Cap Weather? Never :)

Posted by: snowlover2! | January 10, 2008 10:09 AM | Report abuse

Checked the ECMWF re the Sunday night/Monday event. Evidently both the Euro and Sterling tend to have the Metro area too warm ("Boring Forties")for anything more solid than plain ol' rain. Still, six to ten inches would be a nice pleasant surprise to wake up to on Monday morning!

Don't put too much faith in the GFS right now. The Euro seems to be somewhat more accurate for the duration of this La Nina thus far. But it will be interesting to see whether the Euro, GFS and NAM start coming into agreement as this storm forms and approaches us over the weekend.

As for the currently approaching system, there's an interesting feature though not so much of the "wintry" variety. I noticed this morning that the Weather Channel had their cloud-ground lightning detection radar on this morning. Numerous strikes are occurring from Memphis SW into the Arklatex area. The interesting pattern is developing in Tennessee and the Carolinas east of Memphis. Except for the Nashville area which had no rain, lightning strikes were occuring with varying frequency over the metro areas, particularly Knoxville and Columbia. Outside these urban areas the rain was relatively strike free, except for isolated hits in the Birmingham metro area. I was wondering: Do Knoxville and Columbia have that pronounced a heat-island effect, or could there be something else (eg. rush-hour automobile emissions) causing these pockets of instability over Knoxville and Columbia? Since this is the rain shield due to affect us later on in the next 24 hours, perhaps we need to be on the lookout for isolated urban thundershower activity tonight. I believe Doug Hill has it in his forecast on WTOP.

Posted by: El Bombo | January 10, 2008 10:20 AM | Report abuse

El Bombo,

I think the EURO is still fairly wet here even with good shift east. Some mid to upper 30s with a driving rain sounds about right to me.

6z GFS pumps out some snow in the area (fairly significant just west of DC).. but, as you mention, GFS has not been steller in the short-medium term (though I think it has 'seen' some longer term threats well).

It's still too early to give up or commit. Those who've watched the models this season are aware of the seasonal trend for the southeast ridge to become a bigger player as we get near game time... what looks OK 5 days out seems to shift W and NW over time. We'll see if that continues here.

Posted by: Ian, Capital Weather Gang | January 10, 2008 10:48 AM | Report abuse

El Bombo:
10 minutes ago at 10:40, there were numerous lightning strikes in the Nashville area extending into s.w. Ky. Only a few remain in e. Tenn., indicated in the past 10-40 minutes.

Posted by: Augusta Jim | January 10, 2008 10:53 AM | Report abuse

12z GFS (still running) looks to slam us with a big snow event... great track for the whole east coast it seems. Too bad it's a few days off.

http://raleighwx.easternuswx.com/models/gfs/12zgfs850mbTSLPp06084.gif

Posted by: Ian, Capital Weather Gang | January 10, 2008 11:00 AM | Report abuse

I really liked having the link to the NWS forecast discussion. Any way that you can add that link to your new site?

Posted by: Brad | January 10, 2008 11:16 AM | Report abuse

12z GFS is faster, warmer, less QPF, approx. 50 mi. s.e. of the 06z track. If the 12z verifies, the I81 corridor could still receive 2-4 inches of wet snow, but most of the heavy wintry action would be to the n.e. of most of us.

Bring back the 06Z!!

Posted by: Augusta Jim | January 10, 2008 11:24 AM | Report abuse

I put significantly more stock in 12z and 0z model runs since they have far more data input than the secondary (6z, 18z) runs.

Posted by: Josh, CapitalWeather.com | January 10, 2008 11:27 AM | Report abuse

Not sure Augusta, 12Z looks to slam us pretty good

Posted by: Mike from the Blue Ridge | January 10, 2008 11:30 AM | Report abuse

I admit that, if taken literally, the 12Z GFS suggests some wet snow a probability late Sunday into early Monday; the only problem is that it is way too early to take a model run literally. (Some would say that you can't take any model run -- even one 6 hours before an event -- literally.)

Posted by: Josh, Capital Weather Gang | January 10, 2008 11:37 AM | Report abuse

Im just glad the model runs have been more favorable these past couple runs. What is causing the westward shift of the forecasted low now..do you think it may shift back east, or is this an unlikely scenerio..Please somebody respond to my question. Thanks

Posted by: skinsfn | January 10, 2008 11:51 AM | Report abuse

The shift westward is likely due to a better resolution to the upstream energy with subsequent analyses & data.

As an aside, "12z and 0z model runs since they have far more data input than the secondary (6z, 18z) runs" is simply not true with the advent of the satellite era. It is true, however, that these cycles are missing radiosonde observations, the most accurate, direct, reliable information we have.

Posted by: d | January 10, 2008 11:56 AM | Report abuse

Hey Josh Larson did you go to high school in Atlanta?

Posted by: missy | January 10, 2008 11:58 AM | Report abuse

Josh and Mike:
Yes, my comments are based on a literal interpretive comparison between the 06 and 12z GFS. There will certainly be many changes in later runs, but the 12z trend is not good for most in this area, wishing for a significant snowstorm Sunday night and Monday. The Euro shifted east, the GFS now seems to be entertaining that idea. The 12z GGEM is keeping most of the action to the east of the I95 corridor at this latitude.

Having said this, even the 12z GFS looks good, compared to the 07-08 winter experience to date!

Posted by: Anonymous | January 10, 2008 12:02 PM | Report abuse

I claim the 12:02 post

Posted by: Augusta Jim | January 10, 2008 12:05 PM | Report abuse

12z GFS for following Sunday 1/20..Looks interesting as well..

Posted by: skinsfn | January 10, 2008 12:07 PM | Report abuse

Looks like more rain showers for this upcoming Sun/Mon storm.

No cold air in place to support wintry precip except west of the Blue Ridge.

Posted by: Ivan | January 10, 2008 12:09 PM | Report abuse

Is the snow lovers crystal ball going to come back?

Posted by: Aaron | January 10, 2008 4:05 PM | Report abuse

The comments to this entry are closed.

 
 
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