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Posted at 5:00 AM ET, 02/ 2/2010

Some snow now... a lot of snow later?

By Matt Rogers

Two chances for snow: Second one could be major

* 2-4" of snow possible later today/tonight: Full Forecast *

Next Chance of Accumulating Snow: Late today/tonight; Friday-Saturday
Probability of Accumulating Snow (1" or more): 70% and 75%

The first chance of accumulating snow comes later today and tonight from a relatively small storm that could drop up a few inches of snow. See our full forecast for all the details.

Now, on to the bigger threat...

Like clockwork, we are facing yet another potential major winter storm on or overlapping with a weekend. Once again, cold air being driven southward will converge with precipitation being pushed northward Friday into Saturday. There are two notable differences from the past weekend's event, however: (1) The cold air is not expected to be as strong, so temperatures may not be as cold and the potential snow could be of a wetter variety; some mixed precipitation also can't be ruled out yet. (2) The storm is expected to be stronger than last weekend's event, meaning we could see higher winds and heavier precipitation.

Global Forecast System model shows a strong coastal storm dumping precipitation on the mid-Atlantic Friday night. Courtesy NCEP.

Like last week, the weather guidance on this system may vary in the coming days and expectations will likely change a few times before the storm arrives, possibly by around Friday afternoon as it looks now and persisting into Saturday and maybe Saturday night. However, given the impressive combination of cold air supply and moisture this winter -- the very active subtropical branch of the jet stream in this pattern suggests that this storm will have an ample moisture supply -- the mid-Atlantic continues to be in a highly favored position for continued significant snow opportunities.

As usual, storm track will be a key factor determining how much and what type of precipitation we see. If the storm passes too far to the south, then it could lower our accumulation potential (but that has not been the trend this year). Another risk is that if the storm trends too far north/inland, we could see more in the way of mixed precipitation, which would lower accumulations (especially south and east sections).

Here are the current (VERY EARLY) probabilities on accumulations:

25% chance: Less than 1"
25% chance: 1-4"
30% chance: 4-8"
20% chance: 8"+

The Snow Lover's Crystal Ball appears when the potential exists for accumulating snow beyond 24 to 36 hours.

By Matt Rogers  | February 2, 2010; 5:00 AM ET
Categories:  Snow Lover's Crystal Ball, Snowmageddon  
Save & Share:  Send E-mail   Facebook   Twitter   Digg   Yahoo Buzz   StumbleUpon   Technorati   Google Buzz   Previous: PM Update: Just a brief break in the action
Next: Forecast: Snow threatens again... and again


First....and bring on the snow

Posted by: RWRose | February 2, 2010 6:20 AM | Report abuse

I Second that!

Posted by: JW211 | February 2, 2010 7:52 AM | Report abuse

Any chance of a Dec 19th type whammerooski?

Posted by: mandarb77 | February 2, 2010 9:06 AM | Report abuse


As I had posted a couple of days ago, at least one early model run had this area receiving 36-48 inches...more than the Knickerbocker [28 inches] and probably more than the Washington/Jefferson [36 inches each @ Mount Vernon and Monticello].

The current estimates don't look quite that bad, chiefly because the storm appears to cut off before or around 0Z Sunday. Early estimates had us pegged for a three-day or even four-day snow event. A couple of recent model runs are even projecting an inland runner with its attendent potential for a rainy "bust"--though rain and sleet might be more in accord with the large precipitation potentials apparently slated for this system.

Posted by: Bombo47jea | February 2, 2010 11:54 AM | Report abuse

I'm loving all the snow so far, but come on already, when are we going to end up having a major snowstorm during the week? I'm ready for a snow day!

Posted by: BruinGirl2001 | February 2, 2010 12:15 PM | Report abuse

My totally unscientific gut instinct is telling me to enjoy tonight's snow because I have a feeling this weekend's storm will end up under performing.

And of course by under-performing, Im setting the bar at the Dec. 19 storm precip. totals and assuming the Fri/Sat event will be a mixed bag of rain, snow and sleet - i.e. more akin to what we normally get around here.

Posted by: hrc2211 | February 2, 2010 12:26 PM | Report abuse

@ Bombo47jea: I HOPE that first model turns out to be true! 5 FEET OF SNOW?!?! AWESOME!!! :)

Posted by: sigmagrrl | February 2, 2010 12:31 PM | Report abuse

Ok seriously...notice each accumulation predication is around 30%.

25% chance: Less than 1"
25% chance: 1-4"
30% chance: 4-8"
20% chance: 8"+

What kind of predication is this?????

Posted by: lwaya2 | February 2, 2010 4:13 PM | Report abuse

@lwaya2 It means that there's a 50-50 chance of there being more than 4 inches of snow, and that most likely we'll get between 4 to 8 inches.

Posted by: yankervitch | February 2, 2010 4:16 PM | Report abuse

I am supposed to go out to Northern Virginia and Berkeley Springs area of West Virginia this weekend.... think I should cancel?

Posted by: h0ney_suckle_r0se | February 2, 2010 5:43 PM | Report abuse


What do you think of next Tuesday's storm (2/9) - looks to be another coastal storm hitting us in the 18Z GFS run. Less moisture than Saturday, but much deeper cold (so higher snow to rain ratio). Unlike the 2/6 storm, the 2/9 storm does not yet have run-to-run model consistency of even existing. The 2/6 storm has been showing up on the GFS for the past two weeks now as a major storm, and consistently hitting us for a lot of snow (how often do you see a storm showing up over two weeks out that stays consistent!?).

Enjoying the crystal ball!

Posted by: RandC | February 2, 2010 5:45 PM | Report abuse

I have had it with the snow this winter... and with the dopes who want 3 feet of snow. They obviously have never had the pleasure of digging their car out of the snow and then losing their parking space.

Posted by: misterbeauregard | February 2, 2010 8:23 PM | Report abuse

Dear misterbeauregard--3 feet of snow is a sign to stay home, don't even bother digging your car out. :)

Posted by: jhkimball | February 3, 2010 12:03 AM | Report abuse

00Z NAM, interpolated using GFS data beyond it's time frame, indicates that we could get 1.5-2.5 feet of snow (1.5 to 2" liquid) over the weekend. GFS alone indicates 1-2 feet of snow (1.25 to 1.75" liquid).

Also, not liking the 00Z GFS run on next Tuesday: looks like another event like last weekend, very cold air, but combined with much more precip could surprise us with quantities. Going to guess at maybe 6-12" of snow (0.25 to 0.75" liquid).

Anyone notice how cold the entire US is forecast to be the morning of 2/10? Ref:

Posted by: RandC | February 3, 2010 12:18 AM | Report abuse

For lwaya2 who was curious about the four probabilities, you can take this and get an estimate. If I use 0.5 inches for less than one inch, 2.5 inches for 1-4, 6 inches for 4-8 and 12 for 8+, the average is,

(0.25)*0.5 + (0.25)*2.5 + (0.3)*6 + (0.2)*12 = 4.95 inches - lets say 5 inches.

Based on what they know, the expected snowfall amount is about 5 inches. As they get closer to Friday, the probabilities will change (I hope).

Posted by: nidomhnail | February 3, 2010 7:35 AM | Report abuse

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