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Posted at 5:00 AM ET, 02/21/2011

Forecast: Sleet & snow tonight, temps to plunge

By Jason Samenow

Tues a.m. commute may be very slick

updated at 9:30 a.m.

Today's Daily Digit
 
A somewhat subjective rating of the
day's weather, on a scale of 0 to 10.

 

Dismal today, a wintry mess tonight.
 
Get the 'Digit' on Twitter

EXPRESS FORECAST

Today: Cloudy with a few showers. 40s. | Tonight: Rain to sleet to snow. 21-27. | Tomorrow: Snow ends early, then partly sunny. 30-35. | A Look Ahead | Get Express Forecast by E-mail

FORECAST IN DETAIL

After three days in the 70s last week and even in the 50s over the weekend, tonight's forecast is a shocker. Arctic air seeps southward as low pressure develops to our west. Precipitation develops late this afternoon just as temperatures start to fall, resulting in a messy transition of rain to sleet to snow overnight, with the heaviest snow accumulations north of the District. Chilly temperatures follow tonight's storm, but moderate some by mid-week.

Snow Potential Index: 7 (↑) - Odds are good for some slushy accumulation tonight.

 
The SPI is a daily assessment of the potential for accumulating snow for the next week on a 0-10 scale. Get the 'SPI' on Twitter
 

Today (Monday): We're in for a bit of a roller coaster. Under mainly cloudy skies, it feels relatively mild this morning, with temperatures in the 40s to low 50s (southeast of town). But during from late morning through the afternoon, with Arctic air bleeding in from the north, temperatures remain steady or slowly fall. Some spots - especially north of the city - dip all the way back into the 30s by dark. Although there may be some scattered showers this morning and again late this afternoon (30% chance), most precip holds off until tonight. Confidence: Medium

Tonight: Rain is likely this evening but it may fairly quickly mix with and change to sleet, from north to south (roughly from 6 to 10 p.m.). After the changeover to sleet, the sleet likely mixes with and changes to snow, also from north to south (probably from 9 p.m. to 1 a.m.). During these two transitions, temperatures fall from 35-40 (north-south) to 25-30. By 2 a.m., mostly snow should be falling throughout the region before it tapers off by dawn. Lows range from to 20-25. Total snow accumulations range from 2-4" north and northwest of the beltway to mainly 1-2" everywhere else. Road conditions are likely to become very slick. Stay tuned for much more information, including detailed storm timeline, FAQs, impacts scales etc midday. Confidence: Medium

Keep reading for the forecast through next weekend...

Tomorrow (Tuesday): There's a diminishing chance of some lingering light snow through around 10 a.m. with little or no additional accumulation. Then skies gradually clear, but it's cold. Highs range from the low-to-mid 30s. Confidence: Medium-High

Tomorrow Night: Cold high pressure overhead and the likelihood of at least a little snow cover make for a very cold night. Under clear skies, lows range from the low-to-mid teens in the colder suburbs to the low-to-mid 20s downtown. Confidence: Medium-High

A LOOK AHEAD

Cold high pressure remains on top of us Wednesday, but the brilliant late February sun gives temperatures a big boost. Highs should reach the mid-40s. Clear and cold Wednesday night, with lows from the upper teens to the upper 20s (suburbs to city). Confidence: Medium-High

As high pressure moves offshore Thursday, return flow from the south may deliver the nicest, mildest day of the week. Although some high clouds increase during the day, temps should reach well into the 50s. Confidence: Medium

A frontal system moves through the region Thursday night and Friday likely providing some needed rain. Thursday night's lows are in the 40s with highs Friday in the 50s. Skies clear Friday night, and it turns windy and colder, with lows in the 30s. Confidence: Medium

Saturday's probably a little brisk and breezy - but there's a good deal of sunshine. Highs should be in the vicinity of 40-45. Clear and cold Saturday night with lows in the 20s. Sunday's likely mostly sunny and seasonable, with highs 45-50. em>Confidence: Medium

By Jason Samenow  | February 21, 2011; 5:00 AM ET
Categories:  Forecasts  
Save & Share:  Send E-mail   Facebook   Twitter   Digg   Yahoo Buzz   Del.icio.us   StumbleUpon   Technorati   Google Buzz   Previous: Monday night: Rain, sleet, then some snow
Next: Icy/snowy night ahead: Timeline, snow accumulation map, impacts, & FAQs

Comments

What's up with the NWS? How can they not issue a winter weather advisory or a winter storm watch for our area based on the forecast?

Posted by: formerwxman1 | February 21, 2011 7:06 AM | Report abuse

How deliciously unexpected! (Okay, I just wasn't paying attention.) As formerwxman1 says, a WWA would seem appropriate; here's hoping NWS agrees. How about a FedCast? I'm betting on a whole Capitol at least!

Posted by: --sg | February 21, 2011 7:35 AM | Report abuse

They issued winter storm watches for far northwest Maryland, but advisories will probably wait for their midday or afternoon updates (usually when the event is in the first period). http://www.erh.noaa.gov/lwx/

Posted by: MattRogers1 | February 21, 2011 7:49 AM | Report abuse

@CWG

I have fresh SchoolCast apples waiting for a home...tell me where you want 'em!

Posted by: ArlTeacherSnowman | February 21, 2011 7:54 AM | Report abuse

CWG, PLEASE ANSWER,

is there a chance that the forecast changes and the dc area gets 2-4 inches.

thanks

Posted by: SNOWLUVER | February 21, 2011 7:55 AM | Report abuse

Hi CWG,
As a groggy FCPS teacher who just walked into work, I have one burning question: Will there be school tomorrow? I know you don't have an answer, so in the meantime... may we please have zone forecasting as soon as you can make an educated guess?

Posted by: yannos | February 21, 2011 8:01 AM | Report abuse

Snowluver, yes, did you see the post yesterday? http://voices.washingtonpost.com/capitalweathergang/2011/02/mon_night_likely_scenario_rain.html#more There is definitely still low confidence on the specifics of accumulations. Also, Jason's forecast above does say 2-4" are possible north and northwest of the Beltway (in the DC area). Look for more updates on this site today!

Posted by: MattRogers1 | February 21, 2011 8:04 AM | Report abuse

if this unfolds like jason outlined above (rain→sleet→snow) there's no way there's school tomorrow. the "funny" thing is that fairfax county schools are OPEN today to make up for snow days...

keep that warm air outta here today.

Posted by: walter-in-fallschurch | February 21, 2011 8:31 AM | Report abuse

How about a Schoolcast? :)

Posted by: Drano | February 21, 2011 8:33 AM | Report abuse

If I catch my Tuesday plane to Spain,
don't care if it's snow or rain.

But I'd definitely take 1.5" snow tonight, since I called c.a. 11" for the winter, way back when.

Posted by: JerryFloyd1 | February 21, 2011 8:38 AM | Report abuse

hi jerry,
where does the rain in spain stay, mainly...?

Posted by: walter-in-fallschurch | February 21, 2011 9:01 AM | Report abuse

Drano - Hi there, we will get to it later today as the storm approaches. We want to get a better handle on the accumulations, but safer to speculate that school will be cancelled if you are north or west of the Beltway. Still, accumulation forecasts are in the low confidence zone at this time. We think there will be some, but you may also know your locale's reaction best--to a slushy accumulation--perhaps up to 4" well north & west of DC.

Posted by: Camden-CapitalWeatherGang | February 21, 2011 9:05 AM | Report abuse

Will the snow stick? I'm worried it will melt on contact. Isn't the ground to warm?

Posted by: danp3111 | February 21, 2011 9:05 AM | Report abuse

I know it's still Feb. but I wish this "darn" winter would be over. The warmed up weather last week was great, who wants this mess just for a day off from school? This precip (rain,sleet,snow) likely won't be any good for outside "fun". Get me back into the 70's (or at least the upper 40's-50's). That said, it would be nice to have a couple of days of rain, we sure can use it.

Posted by: soyboy99 | February 21, 2011 9:07 AM | Report abuse

danp3111 - conditions will change overnight. Cold air will bleed into the region. Precipitation will be of the frozen variety. The ground will cool. Remember the "Commutageddon" storm? Just mentioning it as evidence that conditions around DC can change quickly even with mild temperatures before a storm.

Posted by: Camden-CapitalWeatherGang | February 21, 2011 9:09 AM | Report abuse

90% of what falls will melt on contact and the rest will only stick to the grass. Nothing to see here.

Posted by: Axel2 | February 21, 2011 9:14 AM | Report abuse

soyboy99 - indeed we can use any precipitation Mother Nature gives us. We do need it!

Posted by: Camden-CapitalWeatherGang | February 21, 2011 9:14 AM | Report abuse

NAM's been looking extremely consistent over the past 3 runs in terms of qpf range for the area. Have the exact amounts for DCA and the temps been as consistent too?

Posted by: Dylan0513 | February 21, 2011 9:27 AM | Report abuse

@Walter, the rain in Spain stays mainly on the grain.

I'll check to see what Ivan the Terrible sculpts on Tuesday. Hopefully enough snow to make lobster.

Posted by: JerryFloyd1 | February 21, 2011 9:42 AM | Report abuse

Mother Nature is having her say about the opening of the ICC tomorrow...

Posted by: apeirond | February 21, 2011 9:47 AM | Report abuse

@Camden

Thanks for the response. I'm hoping for one last snow day!

Posted by: danp3111 | February 21, 2011 9:50 AM | Report abuse

Your forecast for today made less than 24 hours ago called for "Mid-50s to low 60s." How did that forecast suddenly drop to "40's"? What changed?

Posted by: rwalker66 | February 21, 2011 9:51 AM | Report abuse

if the temps stay this low. MORE...SNOW...

SNOW SNOW SNOW
MORE MORE MORE
HAPPY HAPPY HAPPY
JOY JOY JOY!
SNOW SNOW SNOW
TEMPS ARE WAY BELOW
SNOW
SNOW
SNNNOOOOOOOOOOOOOW!

Posted by: benzachr | February 21, 2011 9:58 AM | Report abuse

@rwalker66

The colder air arrived sooner than it looked like it would yesterday. That is all. David Streit first mentioned the uncertainty in the temperature forecast for today last Thursday and it's always been a low confidence forecast. Models have been all over the place with the timing/arrival of the cold air. In the end, it came in sooner. Locations to the southeast are in the mid-50s now, but we've switched to a north wind and will not see that. Hence the forecast was adjusted.

Posted by: Jason-CapitalWeatherGang | February 21, 2011 10:02 AM | Report abuse

@rwalker66

You beat me to the punch. As soon as I walked out the door this morning, I could tell 60s weren't happening. Definitely a "bust" on that forecast if it verifies.

As for invoking "Commutegeddon" as an example here of how conditions can change, I think that's a bit different than this situation. Before that storm, we weren't in the 50's, 60's, and 70's for several days beforehand.

Much of this snow will still melt before it begins accumulating, on grassy areas first and then slushy accumulations on the roads. Road beds are VERY warm right now.

Posted by: ThinkSpring | February 21, 2011 10:03 AM | Report abuse

CWG ---- does this earlier-than-expected arrival of cold air mean that there's a chance this could all be sleet/snow?

Posted by: jms12 | February 21, 2011 10:04 AM | Report abuse

I wish we could get a few inches of nice fluffy snow powder instead of the predicted sleet/slop.
But sleet/slop IS wet....so I'll take it.

Posted by: FIREDRAGON47 | February 21, 2011 10:04 AM | Report abuse

@rwalker

Look at how warm it is just to the south. Woodbridge is in the mid-50s. It is a very tight temperature gradient- and pretty much impossible to predict the placement with much notice. See this map: http://www.erh.noaa.gov/ctp/analysis/temp/region_temp.png

Posted by: Jason-CapitalWeatherGang | February 21, 2011 10:05 AM | Report abuse

Wow, Jason. Is it rare to have such a tight temperature gradient where 25 miles can be the difference between mid 40s and upper 50s? And yeah, I can't see how one can predict temperatures with such a tight gradient.

Posted by: jms12 | February 21, 2011 10:12 AM | Report abuse

It's not in the 50s in Woodbridge right now. I'm just down the road in Manassas and it's 43 here right now.

Posted by: TheJoeGreene | February 21, 2011 10:21 AM | Report abuse

@jms12

Potentially we see less rain, and mostly sleet and snow as a result of the earlier arrival of cold air. Midday update will have more on this.

@TheJoeGreene

I have a reliable source who reported 57 just south of Woodbridge just about an hour ago- but that may no longer be the case if the wind shifted. It's a tight gradient.

Posted by: Jason-CapitalWeatherGang | February 21, 2011 10:25 AM | Report abuse

After getting up to 42F in the mountains east of Front Royal, it's already down to 35...

Posted by: spgass1 | February 21, 2011 10:25 AM | Report abuse

@Jason

Thank you for your explanations. It was just quite depressing to go to bed Sunday night thinking I would see 64 on Monday and then I wake up to find instead I'll be lucky to see 44 today. And to add insult to injury the 50's are close as you mention. Oh, well Spring is on it's way. After today there are only 7 days of meteorological winter left!

Posted by: rwalker66 | February 21, 2011 10:26 AM | Report abuse

It is a beautiful 61 degrees in Fredericksburg - just a beautiful day. It really is amazing how much the temp can vary.

Posted by: cwspy | February 21, 2011 10:26 AM | Report abuse

Wow, the gradient is even more impressive out west. It's a balmy 66 in eastern WV but only 33 in Pigsburgh.

Posted by: bdeco | February 21, 2011 10:26 AM | Report abuse

Little bit of frozen precip already mixing in with the light rain here in Ashburn at 10:37 am. Makes sense since dew point is right at 32. It is going it be a very interesting next 24 hours.

Posted by: kdvols1 | February 21, 2011 10:39 AM | Report abuse

@cwspy - I agree! My thermometer has reached 65 degrees. Wearing shorts today.

Posted by: Showmethesnow | February 21, 2011 10:42 AM | Report abuse

Rain sprinkles in Centreville VA.
The digital backyard thermometer reads 46 & the front one reads 40. Go figure.

Posted by: FIREDRAGON47 | February 21, 2011 10:43 AM | Report abuse

In Lake Ridge (west of Woodbridge), temps have been (and remain) in the low 40's.

Posted by: ZmanVA | February 21, 2011 10:45 AM | Report abuse

firedragon@10:43

Now, THAT is a tight gradient!

Posted by: mcaicedo | February 21, 2011 10:45 AM | Report abuse

CWG

What do you guys think for Montgomery County Public Schools tomorrow? delay?

thanks

Posted by: fortheglory | February 21, 2011 11:03 AM | Report abuse

Currently raining in the Gaithersburg Airpark area & it certainly feels colder than 50.

Posted by: wadejg | February 21, 2011 11:10 AM | Report abuse

http://www.youtube.com/watch?v=IksO_FRK314&feature=related

that is what tomorrow morning will be like.

@fortheglory

MCPS will probably close

Posted by: SNOWLUVER | February 21, 2011 11:11 AM | Report abuse

11a update: back up to 41F

Posted by: spgass1 | February 21, 2011 11:11 AM | Report abuse

@fortheglory

There's still time for things to change, but right now I think we see plenty of school closings around the area tomorrow given the combined impacts some accumulating snow on top of some accumulating sleet. -Dan, CWG

Posted by: CapitalWeatherGang | February 21, 2011 11:12 AM | Report abuse

CWG: Does the earlier-than-expected arrival of cold air bring with it the possibility that the precipitation could be pushed further south than expected and increase qpf for the metro region?

(This wishcast brought to you by the letters S-N-O-W and the numbers 4-6").

Posted by: AsymptoticUnlimited | February 21, 2011 11:16 AM | Report abuse

FIZZLE are the letters that should be used. That's been the case with every "storm" this season except the one in late Jan. I hope I'm wrong, but I've put away the shovel and broken out the lawn chairs.

Posted by: TBAlexandria | February 21, 2011 11:23 AM | Report abuse

firedragon@10:43

Now, THAT is a tight gradient!

Posted by: mcaicedo | February 21, 2011 10:45 AM | Report abuse

That's what she said.

Posted by: ash10 | February 21, 2011 11:25 AM | Report abuse

Please remember there's still a WEEK of meteorological winter by the conventional method of reckoning.

And by MY method of reckoning, met winter isn't really over until Ash Wednesday, the REAL beginning of spring weather! This year, Ash Wednesday isn't until March 9th, about as late as you can get. IMO the beginning of Lent is the onset of spring--and I say this as a Buddhist rather than as a Christian.

Posted by: Bombo47jea | February 21, 2011 11:28 AM | Report abuse

AsymptoticUnlimited and ash10, good ones!

Nice to see some creative humor on this blog :)

Posted by: kolya02 | February 21, 2011 11:30 AM | Report abuse

Cooler and breezier than expected on my run this morning. A bit of light rain in Rosslyn as the streets are now wet.

Posted by: marathoner | February 21, 2011 11:31 AM | Report abuse

Weather.com says 3-5"?

Posted by: dcneedssnow | February 21, 2011 11:31 AM | Report abuse

@AsymptoticUnlimited .... my guess would be that the early-arrival of cold air means that the Arctic high pressure is stronger than was expected. And maybe that could push precip a little south, but let's wait for the experts to weigh in.

Posted by: jms12 | February 21, 2011 11:35 AM | Report abuse

Weather.com says 3-5"?

Posted by: dcneedssnow | February 21, 2011 11:31 AM | Report abuse

That's what she said

Posted by: ash10 | February 21, 2011 11:43 AM | Report abuse

@ noon- Temp has fallen from 45 to 41 degrees in last couple of hours here in NW metro DC.

Hoping for at least 2 inches of snow by morning. I would love to see everything white again before spring.

Posted by: ajmupitt | February 21, 2011 11:45 AM | Report abuse

It looks like the NAM & GFS both are starting to line up in the snowier camp, does it not? Like around the 4-inch amount? Especially since the cold air is in sooner today than originally forecast? That would line up with weather.com's 3-5" amount.

Posted by: flyersindc | February 21, 2011 11:49 AM | Report abuse

"One sort of optional thing you might do is to realize that there are six seasons instead of four. The poetry of four seasons is all wrong for this part of the planet, and this may explain why we are so depressed so much of the time. I mean, spring doesn't feel like spring a lot of the time, and November is all wrong for autumn, and so on.

Here is the truth about the seasons: Spring is May and June. What could be springier than May and June? Summer is July and August. Really hot, right? Autumn is September and October. See the pumpkins? Smell those burning leaves? Next comes the season called Locking. November and December aren't winter. They're Locking. Next comes winter, January and February. Boy! Are they ever cold!

What comes next? Not spring. 'Unlocking' comes next. What else could cruel March and only slightly less cruel April be? March and April are not spring. They're Unlocking."

Kurt Vonnegut from his collection of essays "Palm Sunday". This passage is from a commencement speech he gave to Fredonia State University in 1978 and meant for an Upstate NY audience, but work here as well if you shift the months slightly. I think of "Unlocking" every early Spring and remind myself to expect the unexpected...

Posted by: kedzie | February 21, 2011 11:51 AM | Report abuse

I like that, locking & unlocking. Makes more sense than our current 4 seasons.

Posted by: wadejg | February 21, 2011 12:00 PM | Report abuse

Winter Weather Advisory for most of the region, calling for 2-5 inches.

Posted by: dcneedssnow | February 21, 2011 12:01 PM | Report abuse

Winter Weather Advisory up for DC metro for 2-5 inches of sleet then snow.

Posted by: ajmupitt | February 21, 2011 12:02 PM | Report abuse

ahhh- Winter Weather Advisory is up. Time to increase the vigor of my snow dance :D

Posted by: Snowlover2 | February 21, 2011 12:02 PM | Report abuse

A winter weather advisory has been posted for the DC area for 2-5 inches of snow.

Posted by: will1310 | February 21, 2011 12:03 PM | Report abuse

A winter weather advisory has been posted for the DC area for 2 to 5 inches of snow.

Posted by: will1310 | February 21, 2011 12:04 PM | Report abuse

A winter weather advisory has been posted for the DC area for 2 to 5 inches of snow.

Posted by: will1310 | February 21, 2011 12:05 PM | Report abuse

OPERATION SNOWHOPE HAS WORKED!!!

***********************

Posted by: SNOWLUVER | February 21, 2011 12:06 PM | Report abuse

NAM looks great! much colder earlier. temp has fallen 6 degrees (to 45.0) here since 7:00am. i think this is gonna be WAY colder than people thought. i remember KRUZ et. al. throwing around numbers like 60 degrees(!) yesterday. hahaha boy, talk about your wishcasting...

one thing that concerns me is the projected interruption of yucky sleet. not good - not good at all. that's just dangerous and it robs us of accumulating inches. hopefully, wes will address the sleet thing in his certainly-upcoming update.

Posted by: walter-in-fallschurch | February 21, 2011 12:09 PM | Report abuse

flyersindc

Where did you see 3-5 on weather.com? I was just checking them and they still show 1-2" for DC.

Posted by: TBAlexandria | February 21, 2011 12:23 PM | Report abuse

Temp in NW Spotsy was 62 at 11am, now 52, 10 degree drop in 1 hr. Time to put on the shorts & take the dog 4 a nice long walk.
I might have thrown in the towel a tad early, but still don't see this as a big snow 4 most of this area.
Hopefully this colder weather will keep the stripers at the 301 Bridge, if the wind isn't blowing I'll b fishing Tue.

Posted by: VaTechBob | February 21, 2011 12:25 PM | Report abuse

I see that a WSW has been issued for Frederick Co. Is it possible that far NW Loudoun (Lovettsville, Purcellville) could possibly fall into that range as well since we are closer to that area? Just curious as to how my evening and morning reverse commute will be (I work midnight hours). Thanks for any tips.

Posted by: Novice1 | February 21, 2011 1:02 PM | Report abuse

Just back from a walk up to the grocery. I noticed the cherry trees in front of the townhomes across from Iwo Jima have a few blossoms. I guess they will be a bit surprised with tonight's weather.

Posted by: marathoner | February 21, 2011 1:35 PM | Report abuse

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