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Posted at 1:30 PM ET, 01/20/2010

Wintry mix could cause mess

By Dan Stillman

Snow/sleet accumulation likely late Thurs.-Fri.

* Light mix for southern sections tonight? Full Forecast *
* Coleman's climate change conspiracy | CWG turns 2! Comments? *

Next Chance of Accumulating Snow/Sleet: Thursday Evening-Midday Friday
Probability of Accumulating Snow/Sleet (1" or more): 65%
Most Likely Potential Impact:

If the thaw had you forgetting that it's winter, this forecast should bring your memory back.

A storm system currently taking shape in the central U.S. will spawn a new area of storminess in the southeast U.S. tomorrow. As the second system then works its way up the coast, the D.C. area is likely to see a mix of snow, sleet and rain starting tomorrow evening, probably after (or at least with little impact on) the evening commute. Precipitation could change to mostly snow and sleet (potentially mostly snow in some places) overnight and last through around midday Friday.

The best chance for mostly snow and thus higher accumulations will be north and west of D.C., while the District and points south and east could see more sleet mixing in and thus lower accumulations. With that wildcard of sleet, accumulation potential is highly uncertain. Here are some preliminary snow/sleet accumulation probabilities, which are subject to (and likely will) change...

No accumulation: 5%
Trace-2": 30%
2-5": 35% (most likely as of now)
5"+: 30%

Those north and west of the District should consider the percentages as representative of the higher end of each category (except toward northern Md., where overall precipitation, regardless of type, may be less), while those south and east should consider them as representative of the lower end of each category.

Stay tuned for updates!

By Dan Stillman  | January 20, 2010; 1:30 PM ET
Categories:  Snow Lover's Crystal Ball  
Save & Share:  Send E-mail   Facebook   Twitter   Digg   Yahoo Buzz   StumbleUpon   Technorati   Google Buzz   Previous: John Coleman's climate change conspiracy theory
Next: PM Update: Temperatures cool ahead of storm


35% of 2-5! i'll take that! i was expecting much less. i guess we're having colder temps than expected earlier or something? or maybe the storm's arriving overnight to maximize snow?

Posted by: walter-in-fallschurch | January 20, 2010 1:59 PM | Report abuse

I love it when I lose hope and stop obsessively checking the CWG page, then I come back and there's a happy surprise for me :-)

Posted by: kallieh | January 20, 2010 2:01 PM | Report abuse

Ah! Back to the type of winter storm in DC we are so familiar with. Good luck with all the juggling to come on this one; I'll be checking back obsessively as well. Cold air does look stronger today, so I could see why you mention the possibility of higher amounts...

Posted by: curtmccormick | January 20, 2010 2:05 PM | Report abuse

I would guess with the ground being warm from the last few days, that most of the accumulation would be grass and on the cars?

Posted by: Tom8 | January 20, 2010 2:09 PM | Report abuse

Tom Skilling predicts TWO Arctic outbreaks next week for chicago and points east.

Near record high pressure has been sitting over parts of Siberia & Mongolia. One Mongolian station has reported 31.84 inches or 1084+ mb. The world record is 32.002 inches. [But high pressure of this nature to our north undoubtedly would suppress any snow far to our south!]

Posted by: Bombo47jea | January 20, 2010 2:11 PM | Report abuse

The models show a sharp drop in total precipitation amounts from south to north. As such, it may be south and east that see higher frozen precip accumulations than north and west.

Posted by: bdeco | January 20, 2010 2:13 PM | Report abuse

When there might be a schoolcast for Friday??

Posted by: someonelikeyou | January 20, 2010 3:15 PM | Report abuse

This morning our sidewalks had some icy/sleety spots, so maybe it is cold enough for some accumulation on the streets?

Also obsessive about CWG here in Olney.

Posted by: celestun100 | January 20, 2010 3:15 PM | Report abuse

In the spirit of friendly disagreement, I must say that I personally am far less optimistic about the potential for accumulating snow, especially downtown DC than Dan is. I think most of this event will be in the form of a cold rain with maybe a slushy inch or two of accumulation. Sorry to be the bearer of bad news, snow-lovers :(

Posted by: Josh-CapitalWeatherGang | January 20, 2010 3:26 PM | Report abuse

Thanks Josh ... certainly plenty of room for disagreement more than 24 hours out and with, for a change, what seems to be a storm more typical of the D.C. area than what we've seen earlier this winter -- that is, a lot of uncertainty with both precip. type and precip. amount, as opposed to some of our early-season events which we were able to predict with a little more confidence than is typical around here.

Posted by: Dan-CapitalWeatherGang | January 20, 2010 3:54 PM | Report abuse

I'd also note, Josh, that while mostly cold rain is definitely a departure from the forecast above, a slushy inch or two of accumulation does fall into one of the three main accumulation categories mentioned in the post.

Posted by: Dan-CapitalWeatherGang | January 20, 2010 4:27 PM | Report abuse

This is great! "Watching" Dan and Josh, two highly respected mets on this blog, go back and forth with what looks to be quite different opinions on the storm late Thursday into Friday. Like two computer models spitting out different solutions for a given event. Speaking of models, which model is the favored for this event? From my limited observations it seems as there has been some flip-flopping among the models. One day the NAM says A and the GFS says B and the EURO says C. The next day they all switch. Is there one that Dan is favoring and one that Josh is favoring, thus the different opinions? Do tell. "Enquiring" minds want to know.

Posted by: pjdunn1 | January 20, 2010 4:43 PM | Report abuse

The HPC maps are out showing a Front Royal/Winchester bull's eye. Seems pretty consistent to me with Dan's forecast.

Posted by: spgass1 | January 20, 2010 4:45 PM | Report abuse


Posted by: rockotodd | January 20, 2010 5:44 PM | Report abuse

Bite your tongue rockotodd! I am going to Disney Saturday morning for my birthday, and do NOT want to spend Saturday stuck at Dulles because flights are backed up of cancelled! :-)

Kim in Manassas

Posted by: ksrgatorfn1 | January 20, 2010 6:52 PM | Report abuse

Congrats guys! I hope you get the snow and school closings you want.

Down here in Mobile we had a hellacious storm today that lasted for FIVE HOURS (noon til 5PM). Sports fields and parts of parking lots at our campus flooded, and there was a 4 inch buildup of mud on one of the main roads, so they had to close it for a while to shovel it away. I've never seen rain like that before, and add that to the lightning/thunder, it was kind of scary to walk to class this afternoon. Here's a picture from a sidewalk in front of a building I had class in today...the entire sidewalk was covered in 3 inches of very muddy very fast moving water:

And...we have more on the way:

Posted by: weatherdudeVA | January 20, 2010 7:41 PM | Report abuse

Right on "RockTodd"! Sorry "Kim", but I received some snowshoes for Christmas, and I need to finally break them in for once-and-for all. Bring on the tundra magic!

Posted by: TheAnalyst | January 20, 2010 9:16 PM | Report abuse

So my gut tells me Josh is probably right - but my heart is definitely pulling for Dan!

Bring on the snow!!!

Posted by: hrc2211 | January 20, 2010 9:53 PM | Report abuse

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