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Posted at 8:30 PM ET, 01/18/2009

Alert: Chance of Light Snow Tomorrow

By Jason Samenow

* Full Forecast | Inauguration Weather Forecast and What to Wear *

* 8:30 p.m. update: The latest guidance remains a little conflicting, but I'm slightly more confident we'll see at least some light snow tomorrow (60% chance of at least a dusting). Updated accumulation potential: 40% chance of a dusting or less, 30% chance of a dusting to an inch, 20% 1-3", 10% 3"+. My best bet would be between half an inch and just over an inch. We'll provide comprehensive coverage on the snow threat starting early tomorrow morning.

A fast-moving disturbance, originating from Canada, may pivot through the region tomorrow producing periods of light snow from morning to evening. It's not out of the question that a few locations -- especially along and east of I-95 -- experience a period of moderate snow as the disturbance re-generates off the coast. Light accumulations are possible but not probable.

Probability of Accumulating Snow: 50%
Most Likely Potential Impact:

While tomorrow's disturbance seems to have the best potential we've had thus far this season to produce any accumulation, due to the complex pattern we're in, it's not a given.

Keep reading for more discussion about the risk of snow and accumulation potential...

You may have noticed snow entering and exiting the forecast over the last several days. That's because lots of little disturbances or waves are flowing along a fast moving and shifting jet stream -- and it has been difficult to predict their timing, intensity, and placement. While there is growing confidence that tomorrow's energetic disturbance will, in fact, produce some snow over the region, a slight change in its path/development could mean more or less or no snow.

Here's my best bet at accumulation potential:

Dusting or less: 50%
Dusting to 1": 20%
1-3": 20%
3"+: 10%

Note that while there's a 30% chance we'll receive our first inch, there's a 70% chance we get an inch or less. We'll update this assessment this evening...

By Jason Samenow  | January 18, 2009; 8:30 PM ET
Categories:  Alerts  
Save & Share:  Send E-mail   Facebook   Twitter   Digg   Yahoo Buzz   StumbleUpon   Technorati   Google Buzz   Previous: Forecast: No Go for Accumulating Snow Tonight
Next: Inauguration Weather Forecast: A Cold Wind


no disrespect to capital weather but ill believe it when I see it! I will most deff pray on that 10% for 3+

Posted by: clintonportis17 | January 18, 2009 1:36 PM | Report abuse

No disrespect taken :)

As the post implies, most likely scenario is around a dusting -- but we'll know more with additional model runs later this afternoon and tonight.

Posted by: Jason-CapitalWeatherGang | January 18, 2009 2:52 PM | Report abuse

Any chance we get a little bit of snow later tonight out here in annapolis from the moisture currently moving up the coast?

Posted by: snowlover | January 18, 2009 3:12 PM | Report abuse

Not gonna happen!


Posted by: stinkerflat1 | January 18, 2009 4:25 PM | Report abuse

A light snow fell here during the last hour in Warren County east of Front Royal providing a 1/16" dusting.

Posted by: spgass1 | January 18, 2009 7:41 PM | Report abuse

I'm still waiting for the day I can come to this site and see

Alert: Major snowstorm chances increasing

haha just maybe this year!

Posted by: clintonportis17 | January 18, 2009 7:46 PM | Report abuse

clintonportis17: That's only happened once in my entire life. It was the 2003 snowstorm that went from a dusting on the 6pm news to 1-2 ft by the 6am news. That was one of the happiest days I can remember from high school... haha.

Posted by: JTF- | January 18, 2009 8:10 PM | Report abuse

MLK day I am thinkin' 1-3 and thats about it tomorrow......... Looks like a nice storm scenario lining up for later in the week. Thurs night thru Sun needs to be watched as it could be the biggie we are waiting for!! Plenty of moisture but the good ol rain/snow line will be the deciding factor.

Posted by: Hurrizzard11 | January 18, 2009 9:41 PM | Report abuse

To edit my post....tomorrows snow...if any at all will likely fall along and south and east of the I95 corridor.

Posted by: Hurrizzard11 | January 18, 2009 9:44 PM | Report abuse

Jason - what's your long-range take on a potential storm next weekend? Love the blog. Keep up the good work!! My son (10) and I love your commentary.

Posted by: someonelikeyou | January 18, 2009 10:02 PM | Report abuse

I just hope this doesn't mess up Inauguration Day activities. I'm planning on going down and I don't want it to be a wet mess! If anything, it will be a dry mess!

Posted by: PeterBethesda | January 18, 2009 10:40 PM | Report abuse


Thanks for the nice feedback. I haven't spent a lot of time looking at the late week threat. Looks to be another complex set of circumstances, and at the moment, I'm not overly bullish about snow potential.

Posted by: Jason-CapitalWeatherGang | January 18, 2009 11:27 PM | Report abuse

Wow, this snow forecast keeps constantly changing...though we still get tabbed for a "dusting" rather than the "Knickerbocker" I'm looking for. Not sure about this "later this week" deal either, since we keep going into the high thirties and "boring forties" with their attendant threat of plain ole boring ole RAIN!!! This winter, with its [supposed!] promise of "La Nada" snowbanks, has thus far been one of the more boring winters in my thirty-some years in the D.C. area. Global warming has really done a number on the big-snow events of yesteryear. Some sources tell me we've slipped back into weak "La Nina", which may account for the lack of snow cover. There has also been a tendency for storms to track consistently to our north so far. Meanwhile, meteorological winter continues to tick away...

Posted by: Bombo47jea | January 18, 2009 11:55 PM | Report abuse

Siberian "Cold Pole" conditions: 2:30 PM local;

Verkhoyansk: Cloudy, minus 11 F

Oymyakon: minus 30 F

Posted by: Bombo47jea | January 19, 2009 12:04 AM | Report abuse

I'm just glad that this winter we're seeing more seasonable temps. last winter was just wimpy. Don't get me wrong, want snow as much as the rest of us.

Posted by: novajeffc | January 19, 2009 1:14 AM | Report abuse

Bombo -

Your sources are correct. We have indeed slipped back into a weak Nina. Combine that with the fact the atmosphere was, even before the weak Nina, still in a largely "Nina" configuration thanks to the recently ended strong Nina, and that explains much of our winter thus far.

The Nina isn't as strong as the prior one, so the SE Ridge is not as powerful, which helps our ability to get cold temps. HOWEVER, the storm track aspect of this Nina is alive and well. For DC to get big snows, we need "split flow" with an active southern branch of the jet stream. A hallmark of Nina's is to NOT have split flow and have only the Northern branch active - which results in the northern storm track we have seen.

Nina, not global warming, accounts for this winter. It is basically always error to suggest the events of a given season (or even seasons) is "climate" and the result of global warming. Global warming is a much longer term thing.

Posted by: jahutch | January 19, 2009 1:41 AM | Report abuse

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