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Posted at 3:45 PM ET, 03/ 2/2010

PM Update: Storm gets closer. Close enough?

By Ian Livingston

Snow accumulation forecast on the rise

* Varying predictability of snow | New England "bomb" | CWG T-Shirts! *
* Outside now? Radar, webcam & more: Weather Wall *

We're watching a storm move up the East Coast and even as it gets started around here, some questions remain. The storm has trended closer and wetter both in ground observations and model guidance, which gives us growing confidence of higher impact on the area. One of the harder questions to answer is how close to freezing temperatures will drop tonight, and thus how much of the snow that falls will accumulate. After highs topped out in the low-and-mid 40s, they will only slowly settle through the 30s this evening.

Through Tonight: Light rain, mixed with snow, continues to move into the area the rest of the afternoon and evening. As the evening and night progress much of the precipitation should change to snow, especially north and west of I-95. Lows fall to within a few degrees of freezing most spots. Accumulation around 1-2" is possible on grassy and elevated surfaces, with a light coating not out of the question on some roads.

Tomorrow (Wednesday): We'll wake up to a low pressure sitting off the coast and sending more precipitation into the area. Light snow, potentially changing back to rain in spots, should persist into midday as the low pulls off to the northeast. Some additional accumulation is possible. Highs should rise to around 40.

SchoolCast (Wed.)

Accumulation: We currently expect about 1-3" of snow to accumulate overnight and tomorrow, mainly on grassy surfaces, but with a dusting to 1" possible on roads. A slight additional shift west could mean more snow, while a slight drift east could mean less. Here's our best outlook on probabilities. Since the situation is still evolving, we will update by 11 p.m...

Dusting-1": 35%
1-2": 35%
2-5": 20%
5"+: 10%

See Matt Rogers' full forecast through the week. And if you haven't already, join us on Facebook and follow us on Twitter.

By Ian Livingston  | March 2, 2010; 3:45 PM ET
Categories:  Forecasts  
Save & Share:  Send E-mail   Facebook   Twitter   Digg   Yahoo Buzz   StumbleUpon   Technorati   Google Buzz   Previous: The varying predictability of snowstorms
Next: Sloppy snow and rain mostly not sticking


First ! I think...

Thanks CWG for the update !

Posted by: letitsnow | March 2, 2010 3:54 PM | Report abuse


I'm dancing as fast as I can!

Posted by: teezee210 | March 2, 2010 3:56 PM | Report abuse

Can I get a woot-woot for that 10%!?

WOW this is great; DC winters are usually so boring and disappointing!

THANK YOU, global warming! (I say the tongue-in-cheek, please don't flame me for it; I'm just having a little fun)

Posted by: kolya02 | March 2, 2010 3:59 PM | Report abuse

Just took a look at the 18 UTC NAM run.. looks like those accums may have to be bumped up even more. I hate to say it but Joe Bastardi may be right on this one. That said CWGs approach to forecasting this storm(ie lack of hype and defining uncertainties) is the right way to go!

Posted by: where_is_snowmonster | March 2, 2010 4:01 PM | Report abuse

Drizzle in Manassas VA.

Posted by: FIREDRAGON47 | March 2, 2010 4:04 PM | Report abuse

where_is_snowmonster, we factored in the 18z NAM to our thinking. If it were to trend west again totals may need to rise.

Posted by: Ian-CapitalWeatherGang | March 2, 2010 4:07 PM | Report abuse


Thanks ... we waited to publish this post until after looking at 18z nam. It was a dramatic shift west, but temps having trouble getting down to freezing swayed us to not jump any higher than what you see above. If this evening's models trend further west than we'll probably have to adjust higher. Right now, NAM may not be the best model go by, b/c it's always suspect when a model shifts as dramatically as it did from this morning's run to this afternoon's run. Some of the models that have been more consistent, though still with an overall westward trend, support the forecast above. But, as with most storms around here, you'll want to stay tuned. -Dan, CWG

Posted by: CapitalWeatherGang | March 2, 2010 4:08 PM | Report abuse

I'm feeling good about this one...I have some neighbors that freak out everytime there is measurable snow here...I see a little nervousness outside. This is not a scientific process, but it has worked for me in the past.

Posted by: letitsnow | March 2, 2010 4:08 PM | Report abuse

I think your percentages are spot on. Even if the 12z GFS or 18z NAM verified, it'd probably only be cold enough for 1-2".

It's interesting how the GFS and now the NAM have been trending west over the last couple runs. You have to wonder if tonight's runs are going to bring the storm even more west...

Posted by: Dylan0513 | March 2, 2010 4:15 PM | Report abuse

keep us posted on the NNQ (neighbor's nervousness quotient).

Posted by: walter-in-fallschurch | March 2, 2010 4:16 PM | Report abuse

No problem Walter, I am keeping an eye out for any increase in the NNQ (thanks for giving it a more scientific sounding name)!

Posted by: letitsnow | March 2, 2010 4:35 PM | Report abuse

I have the NNQ also. However, I must tell you that unfortunately, for snow lovers anyway, my neighbors have parked facing in!

Not only that, they have removed the tv tables and lawn chairs that marked "their" parking spots.

Another bad sign- I found my yardstick which I lost during the 2nd Feb. blizzard.

Seriously, we have mainly rain, mixed with little tiny snowflakes here in Olney, mD.

Posted by: celestun100 | March 2, 2010 4:49 PM | Report abuse

haven't seen a flake here. light rain.

Posted by: walter-in-fallschurch | March 2, 2010 4:51 PM | Report abuse

My son is traveling to Harrisonburg tomorrow and on Thursday to Newport News. I hope this storm stays as far east as possible (like over Africa). I'm so done with winter and done with snow for a decade.

Posted by: griffin1108 | March 2, 2010 4:53 PM | Report abuse

If this turned out to be a big storm, maybe we could name it "Bob's revenge"

Posted by: TopperTed | March 2, 2010 4:54 PM | Report abuse

I'm all up for that 10%

Posted by: KelsiN | March 2, 2010 4:56 PM | Report abuse

@letitsnow, I will be waiting for the 0z run of the NNQ.
@walter, Love the acronym.

Thanks for the laughs, all!

In Laytonsville, MD, still have light precip. switching between rain and snow, but more snowy at the moment.

Posted by: dprats21 | March 2, 2010 5:02 PM | Report abuse

I guess I am not going to get my one last blizzard for the winter....temps are getting warmer and looks like it AINT gonna happen......BUMMMMMMMED!!!

Posted by: akamrspris | March 2, 2010 5:02 PM | Report abuse

To all the would-be "come on 10%" snowmaniacs - regardless of what you see on radar, have you checked the forecast temperatures, in addition to your obsessing over model runs? Temps in the high 30s and low 40s are not conducive to accumulations of your precious white stuff. Too bad, so sad.

The sun is my friend. ;)

Posted by: nocando | March 2, 2010 5:11 PM | Report abuse

Temps will not be a problem if the precip comes down heavy enough. Right now I would say about 2-4 at National and warm spots and 4-6 NE of town.. with lots more up near Boston!

For example check out the obs Freeman Field Airport in Louisa county south of DC. THey have already switched to snow at 37 degrees at 4:40 after cloudy and 43 at 1.

Posted by: where_is_snowmonster | March 2, 2010 5:12 PM | Report abuse

Tuesday Weather Rant;

This is what drives me nuts about what I call "weather model gazing". 24 hours ago some in our little amateur weather forecasting community here at CWG had virtually played out this storm before the storm had even begun to take shape. (BTW, I do not include the CWG in this rant or consider them armatures). Although this storm may not result in much snow I think we all can agree that it is not the event the Sunday/Monday models predicted. The weather model may be the greatest meteorological innervations since the thermometer but they are a tools intended to be used for forecast guidance. Total reliance on their outputs can be just dangerous. (Although they sure can be a lot of fun to discuss).

End of Tuesday weather rant.

Posted by: ntrlsol | March 2, 2010 5:15 PM | Report abuse

Doug Hill still sticking with an inch on grassy least via WTOP.

While I like snow...I have been glad to see it slowly vanish over the last few weeks. I really don't have a desire to see it re-appear in much more than a little white coating anytime between now and say, December...

Kim in Manassas

PS: light drizzle outside my office window in Arlington

Posted by: ksrgatorfn1 | March 2, 2010 5:22 PM | Report abuse

Light snow in Fairfax City.

Initially started as a light rain/mist, then mixed with snow, now all snow.

Posted by: hrc2211 | March 2, 2010 5:35 PM | Report abuse


rain here.

can i assume that even if/after it changes to snow, it will take a while to start sticking - even on grassy areas?

Posted by: walter-in-fallschurch | March 2, 2010 5:47 PM | Report abuse


Yes. Will take a while to stick even on grass if intensity is light (which looks like the scenario for the time being), but moderate snow (possible later, after midnight) would tend to start sticking on grass more quickly.

Posted by: CapitalWeatherGang | March 2, 2010 5:56 PM | Report abuse

OK, I have noted that the "participants" in my NNQ study have demonstrated a definite increase in "odd behavior" over the past hour and a half. One participant has backed in to the parking space and is pacing in and out of her house...looks at the car, looks at the sky, repeat over and over. It hasn't reached frenzied proportions yet, but the strangeness is on the rise. They seem to have a sixth sense here about the weather, snow psychics, if you will. Next update...soon.

Posted by: letitsnow | March 2, 2010 6:00 PM | Report abuse

I'm dancing a snow jig and doffing my CWG t-shirt, which arrived today (quick delivery and I didn't specify premium shipping).

Now, just be to sure, I gotta' go empty some ice cube trays....

Posted by: JerryFloyd1 | March 2, 2010 6:01 PM | Report abuse

My neighbor just sold his house and grew a thick winter coat.

Posted by: Groff | March 2, 2010 6:07 PM | Report abuse

letitsnow, you said,
"One participant has backed in to the parking space and is pacing in and out of her house...looks at the car, looks at the sky, repeat over and over."

that's DEFINITELY moderately nervous behavior - maybe she saw something on a t.v. news weather report? anyone repositioning snow shovels? spreading salt on their walkways?

Posted by: walter-in-fallschurch | March 2, 2010 6:09 PM | Report abuse


Posted by: shamuballeno | March 2, 2010 6:13 PM | Report abuse

Maybe she's married to Joe Bastardi? Could you imagine being married to him -- "hon, be sure to salt the porch and driveway, we're gonna get 20 inches tonight!" at least 3 times a week?

I love that Bastardi guy, though :)

Raining and snowing here in Lake Linganore. Nothing sticking, and I was able to go outside wearing just a vest (meaning it's likely not below freezing).

Posted by: JSTF | March 2, 2010 6:14 PM | Report abuse

Walter, I have not observed any salt spreading or shovel gathering..yet. I don't know where the participants get their intuition concerning these events. I think there may be some genuine psychic activity going on here. I can't ask the participants why they are acting the way they are, because they don't know they are participants in a meteorological/psychic study. Will continue to monitor for additional eratic behavior suggesting snow arrival.

Posted by: letitsnow | March 2, 2010 6:25 PM | Report abuse

Shamu is back

Que quieres decir con "woom, woom, etc?

Posted by: celestun100 | March 2, 2010 6:31 PM | Report abuse

Wahoooo! Wishing for a big surprise grande finale for our snow season!!! C'mon baby!!!

Posted by: BigMama7 | March 2, 2010 6:43 PM | Report abuse

Looking at radar and seeing that temps are not moving much I wonder if the 18z NAM was a bit of a blip.

Posted by: Ian-CapitalWeatherGang | March 2, 2010 6:43 PM | Report abuse

yes, keep us posted. any they musn't know they're being studied - it would corrupt the results.

others: any NNQ reports from the grocery store? any french toasters (bread, milk, eggs) out yet?

Posted by: walter-in-fallschurch | March 2, 2010 6:45 PM | Report abuse

Walter, nope but french toast does sound kind of good...

Lovin' the NNQ. I'm at Catholic's law school right now, and I guess the version of it here would be the level of chatter concerning the possibility of classes being either delayed or cancelled tomorrow. Unfortunately, such discussion is negligible.

Posted by: nlcaldwell | March 2, 2010 6:59 PM | Report abuse

In past storms, CWG (love you guys!) has stated that radar isn't the best way to understand what is happening on the ground, and where the leading edge of the storm may be. Is this storm different? For instance, it looks like rain for most of the area DC- south, except once to Fredricksburg it turns to ice/sleet (pink!) west of 95, and then snow out near Culpepper. Are these radar readings more accurate than in previous storms? MANY thanks!

Posted by: sgc4 | March 2, 2010 7:09 PM | Report abuse

Light snow and 32 degrees here in Eldersburg. No sticking yet, as highs were near 40.

Posted by: DLO1975 | March 2, 2010 7:13 PM | Report abuse

Now, this is more like what we are used to in this area. Many days of talking about the possibility of snow, and when the magic day arrives, nothing.

It's like a summer day in Scotland here in the City of Manassas, cold and slight drizzle.

Posted by: irish031 | March 2, 2010 7:30 PM | Report abuse

most of the precip seems to be done. Wanted one last snowfall, but now I'm with ThinkSpring...bring on the warm sunshine, budding flowers, and leaves on the trees!

Posted by: BH99 | March 2, 2010 7:31 PM | Report abuse

@kolya02, I see your "Woot-Woot", and raise you by an AMEN!

Posted by: TheAnalyst | March 2, 2010 7:43 PM | Report abuse

@BH99, what are you talking about? The main focus of this system isn't even past the Carolinas yet.

Posted by: TheAnalyst | March 2, 2010 7:46 PM | Report abuse

Okay. Some points to ponder for tonight's event:
1- The surface temps. The temps in the area are well above freezing. While you don't need freezing temps at the surface to have snow, it goes a long way in helping the accumulation totals, especially when the precipitation is light.
2- The surface low is forecasted to develop off the NC coast. It's eventual track will determine the amount and intensity of the precipitation. The 18z NAM does bring the center of the offshore low closer to our area. Do we believe that? I don't. I would like to ( I love snow) but I believe it is an anomaly.

In conclusion: Without a source of cold air at the surface and without the support of moderate precipitation to pull upper level temperatures to the surface, we won't see much in the way of accumulating snow. It may look nice and the grass may be covered, but the streets and DCA (of course!) won't see much.

Posted by: pjdunn1 | March 2, 2010 7:55 PM | Report abuse

Light snow along the Blue Ridge in eastern Warren Co... 3/16th inch accumulation so far... 28.8F

Posted by: spgass1 | March 2, 2010 7:59 PM | Report abuse

My neighbor just sold his house and grew a thick winter coat.

Posted by: Groff

Cracked me up.

It's only dropped from 36 to 35 the past several hours here in Alexandria.

Posted by: Snowlover2 | March 2, 2010 7:59 PM | Report abuse

Well it WAS snowing here. Finished dinner and nothin' doin'.

Posted by: Brian-CapitalWeatherGang | March 2, 2010 8:15 PM | Report abuse

If the situation is "evolving," that must mean it is getting better, as in snow chances increasing?

Posted by: fleeciewool | March 2, 2010 8:22 PM | Report abuse

Centreville VA 35 degrees, light snow mixed with drizzle.

Posted by: FIREDRAGON47 | March 2, 2010 8:44 PM | Report abuse

I heard rumors it was snowing outside in McLean, but just came back in from taking the garbage out and it's definitely rain. Doesn't feel remotely cold enough for snow.

Posted by: HokieTerp | March 2, 2010 8:57 PM | Report abuse

36, mostly snow in Glover Park.

A thank you to those who reassured me that flushing a tray of ice cubes can be done without serious injury to the commode.

And it does work, although it takes a while for those ice cubes to turn into snow flakes.

Posted by: JerryFloyd1 | March 2, 2010 8:58 PM | Report abuse

Moderate snow here in Oak Hill. Trace accumulation..

Posted by: Beachboy4ever | March 2, 2010 9:34 PM | Report abuse

We are now at 32 degrees in Ashburn (Loudoun County), and the Snow is picking up the pace a bit in the last 20 minutes

Posted by: kdvols1 | March 2, 2010 9:37 PM | Report abuse


No se sabe.

I just know someone posted "WOOOM WOOOOOM WOOOOOOM!" and it made CWG's list of favorite posts from the this winter. But no worries. I don't really get it either. lol

Posted by: SpeedLimit186000 | March 2, 2010 9:38 PM | Report abuse

Temperatures at several spots in Olney are now below 32, with light snow. Cars and grassy areas have a light coating of the white stuff.

Posted by: SnowLoverOlneyMD | March 2, 2010 9:40 PM | Report abuse

Temperatures and wet bulbs are both above freezing. Going to take some heavy snow to get much accumulation. Couple that with the warm ground temperatures and there just isn't going to be much to worry about with this storm.

Posted by: dcawx | March 2, 2010 9:41 PM | Report abuse

Light snow in Darnestown; we have just the first tinge of white on the grass in places where the old snow has melted.

Posted by: curtmccormick | March 2, 2010 9:45 PM | Report abuse

Rain has transitioned to snow in Lake Ridge. Nothing sticking.

Posted by: ZmanVA | March 2, 2010 9:47 PM | Report abuse

There's something to be said for 2 to 3 inches of snow on the grass and nothing on the roads. It will look nice and pretty, but without another big disruption. As much as I like snow, I'm not sure I want the kids going to school in July.

Posted by: ElJocko | March 2, 2010 10:12 PM | Report abuse

3/8ths" along the Warren/Fauquier line. Current conditions: Fog, 28.6F

Posted by: spgass1 | March 2, 2010 10:20 PM | Report abuse

Light snow in Laytonsville, decks, cars and grassy areas coated. All snow. Roads are fine. Temp. is 33.

Posted by: dprats21 | March 2, 2010 10:33 PM | Report abuse

I guess you know you have a problem when you stay up just to read a CWG update on a 1-3" event :-)

Posted by: spgass1 | March 2, 2010 10:56 PM | Report abuse

spgass1 - you're not alone!

Posted by: acwarrate | March 2, 2010 11:01 PM | Report abuse

acwarrate and spgass1:
Sad to say, but here I am with you, just checking to see....hopefully

Posted by: manassasmissy | March 2, 2010 11:05 PM | Report abuse

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