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Posted at 9:05 AM ET, 01/27/2010

Forecast: Calm into tomorrow, then action begins

By Dan Stillman

Turning colder tomorrow night... followed by snow?

* Details on snow threat: SLCB | Wild weather out West *
* Outside now? Temps, clouds & more: Weather Wall *

Today's Daily Digit
 
A somewhat subjective rating of the day's weather, on a scale of 0 to 10.
 
5Similar to yesterday but with more sun at times. So we'll bump the digit up by 1.
 
Get tomorrow's 'Digit' on Twitter tonight

EXPRESS FORECAST

Today: Partly sunny. Mid-40s. | Tonight: Partly cloudy. Mid-20s to low 30s. | Tomorrow: Partly sunny. Upper 40s to low 50s. | A Look Ahead | Get Express Forecast by E-mail

FORECAST IN DETAIL

The forecast consists of rather straightforward January stuff today and through part of tomorrow. Then, the action begins with a strong cold front set to come through late tomorrow, followed by the chance of snow late Friday into Saturday. To be honest, there are still more questions about the potential snowstorm than there are answers. But do read on for the details as we see them now.

Temperatures: Current area temperatures. Powered by Weather Bonk. Map by Google. Hover over and click icons for more info. Click and hold on map to pan. Refresh page to update. See map bigger on our Weather Wall.

Today (Wednesday): A mix of clouds and sun today with highs ending up around the mid-40s -- right around where you'd expect them to be this time of year. Confidence: Medium-High

Tonight: Partly cloudy with lows in the mid-20s to low 30s (suburbs to city). Appreciate these lows slightly above the seasonal norm. Tomorrow night will be much colder. Confidence: Medium-High

Keep reading for the forecast through the weekend...

Tomorrow (Thursday): The day starts off feeling like a run-of-the-mill January day with partly sunny skies and temperatures climbing toward and into the 40s. But as a cold front approaches, afternoon highs may spike as high as the low 50s with increasing winds. The front should come through during the late afternoon or early evening, possibly with a rain or snow shower, after which temperatures start to tumble. Confidence: Medium

Tomorrow Night: Mostly clear early and probably breezy in the wake of the cold front. Lows drop all the way down to the upper teens to mid-20s (suburbs to city) with a chance that some high clouds work their way in overnight or toward morning. Confidence: Medium-High

A LOOK AHEAD

Friday and Saturday should be quite cold with highs only in the 30s on Friday and 20s on Saturday. Could see some accumulating snow late Friday into Saturday. Whether we do, and how much, depends on the track of a storm coming up from the south. See the Snow Lover's Crystal Ball for more details. Confidence: Low

Any snow should be finished by Saturday night but we stay cold Sunday with highs in the 30s. Confidence: Medium

By Dan Stillman  | January 27, 2010; 9:05 AM ET
Categories:  Forecasts  
Save & Share:  Send E-mail   Facebook   Twitter   Digg   Yahoo Buzz   Del.icio.us   StumbleUpon   Technorati   Google Buzz   Previous: PM Update: A flurry or two, then clearing
Next: Late Friday-Saturday snow threat still evolving

Comments

Are the GFS and NAM settling into a light snow scenario for the DC area? It's a little early yet witht NAM, but 24hrs ago the GFS had us at about 8" of snow, 12 hours ago a total miss, and now at about 2-3" of snow. I think we are going to need some seriously high liquid to snow ratios to hit my prediction of 5"-8" that I made yesterday. Let's hope this thing shifts 150 miles north over the next 60 hours:)

Posted by: snowlover | January 27, 2010 5:11 AM | Report abuse

This one's not as obvious as the storm of Dec 19th, which screamed "Major Storm" from 2-3 days out. That tells me less is the more likely choice. But it's great to be back in an active pattern after a welcome three-week break. It will be interesting to see what Winter Part II brings...

Posted by: curtmccormick | January 27, 2010 7:21 AM | Report abuse

I always say give me the cold air - I'll find the precip. We're not going to have another 12/19 for a while. And this is DC, so let's face it, something that sticks would be great.

Posted by: fleeciewool | January 27, 2010 7:44 AM | Report abuse

I'm just glad we have the cold air... so at least there isn't any question that what will come down, will be snow... hopefully it will be a decent storm - 3-4 inches would be my call...

Let it snow! :)

Posted by: MKoehl | January 27, 2010 9:42 AM | Report abuse

GFS is now showing snow for Saturday and Sunday (in addition to next Wed, Sat and Sun). With the models flip floping regularly I'm really hoping that means all the naysaying will turn into snow!
But really, what is the (or two) major factor contributing to the models changing?

Posted by: Bainbridge | January 27, 2010 9:52 AM | Report abuse

Maybe it is just my imagination but it seems like it is much more likely for us to have precip of one form or another on weekends. Should be a smaller percentage chance but it sure doesn't seem that way!

Posted by: CliftonJohn | January 27, 2010 10:02 AM | Report abuse

@Bainbridge

I like that long term GFS outlook. Even if there is a bust or two in there, something is bound to happen!

Posted by: bdeco | January 27, 2010 10:05 AM | Report abuse

@Bainbridge

There are really a host of factors that cause models to fluctuate on storm track and precipitation amount. For example, the amount of ridging of the jet stream in the western U.S. can affect how deeply the jet stream dips in the eastern U.S., which can be the difference between a storm that rides up the East Coast or tracks more out to sea. Also, small changes in when and where a storm develops and how fast it moves can affect if, when and how the storm interacts with other weather systems at different levels of the atmosphere across North America. The models themselves and the observations fed into the models are not perfect, and so inaccuracies and fluctuations in these and other components can cause models to sway back and forth between differing large-scale and small-scale scenarios, which can have significant implications for the weather you and I end up experiencing.

Posted by: Dan-CapitalWeatherGang | January 27, 2010 10:56 AM | Report abuse

This is possibly a very obvious and novice question, but does a "ridge" in the jet stream refer to a protrusion up, away from the surface, higher in altitude or does it refer to a wave parallel to the surface, but bending north or south or something?

Posted by: manassasmissy | January 27, 2010 11:15 AM | Report abuse

@manassasmissy

No worries ... we like novice questions here. The answer is the latter -- a wave parallel to the surface. So typically, the more the jet stream bulges northward in the western U.S., the more it dips in the eastern U.S. The dipping in the eastern U.S. allows storms to ride up the south-to-north (or southwest-to-northeast) component of the jet stream on the eastern side of the dip. When the jet stream is flatter, then storms will tend to follow that more west-to-east flow out to sea rather than south to north up the East Coast.

Posted by: Dan-CapitalWeatherGang | January 27, 2010 11:58 AM | Report abuse

A high-pressure ridge also extends farther into the atmosphere...there's more air piling up in a high pressure area, and it tends to sink towards the earth and flow away from the ridge. The clockwise or counterclockwise flow [depending on whether you are in the Northern or Southern Hemisphere] is imparted by the Earth's rotation, and is greater the farther you are from the Equator.

Likewise, there's less air in a low-pressure trough, and it tends to rise as outside air flows in, becoming a counterclockwise flow to us and clockwise for Australians, South Africans, New Zealanders, Chileans and Argentines. Consequently the "heights" of equipotential lines [e.g. 500 mb.] are lower in a trough, higher in a ridge, on an upper-air chart.

Posted by: Bombo47jea | January 27, 2010 12:47 PM | Report abuse

I'd like the expected wind direction to be mentioned along with the expected wind velocity.

Posted by: hawknt | January 27, 2010 4:53 PM | Report abuse

The comments to this entry are closed.

 
 
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