Network News

X My Profile
View More Activity
The new Washington
Post Weather website
Jump to CWG's
Latest Full Forecast
Outside now? Radar, temps
and more: Weather Wall
Follow us on Twitter (@capitalweather) and become a fan on Facebook
Posted at 4:00 PM ET, 02/19/2011

After winds & more warmth, could it snow?

By Dan Stillman

originally posted at 2:05 p.m, updated at 4:00 p.m.

What about those winds? See Ian's full forecast for the latest on today's powerful winds (last updated at 3:45 p.m.) - they're causing power outages, brush fires, and have blown over the National Christmas Tree - and the weather through the rest of the holiday weekend.

I'm not one for exaggerating or overhyping the weather, but it sure does seem to get wilder by the moment around here lately. Even as today's winds gust over 50 mph in the wake of yesterday's record-breaking mid-to-upper 70s, we have another weather threat to track - a chance of snow Monday night into early Tuesday.

Next accumulating snow chance: Monday night into early Tuesday
Probability of more than 1" of snow: 30%
Probability of more than 4": 10%

An initial storm tracks mostly to our north Sunday night and Monday. It could produce a few rain showers during that time, but its main impact will be to draw warm air up from the south, probably pushing Presidents Day highs into the pleasantly mild 60s. It's a likely second storm that brings the chance of light rain late Monday afternoon through mid-evening, and then the likelihood of rain changing to snow (maybe some sleet in between) later Monday night as temperatures tank and precipitation possibly becomes heavier.

At this point, because we're still more than 48 hours away and because it's very hard to say how fast both air temperatures and ground temperatures will fall Monday night, our snow accumulation forecast by early Tuesday morning ranges from little to none, to a few inches that could impact the Tuesday morning commute.

Keep reading for a model discussion, including thoughts from CWG's winter weather expert...

MODEL DISCUSSION

Precipitation: How much?

Disregarding the type of precipitation for the moment, let's take a look at how much we might get. Most models (the GFS, Euro and SREF) show the potential for at least .25-.5" of liquid equivalent precipitation Monday night into Tuesday morning. The NAM model is wetter and puts the metro area within a swath of near 1" totals. In some runs, the GFS has placed the D.C. area close enough to the northern fringe of the moderate to heavy precipitation that if the storm shifts just a little bit south we could be looking at very little precipitation.

Generally speaking, though, there's pretty good agreement among both the operational and ensemble models that chances are fairly good that we see at least .25" if not a decent amount more.


This morning's GFS model forecast for 1 a.m. Tuesday shows precipitation falling as high pressure to the north/northwest funnels cold air southward into the D.C. area.

Temperatures: Cold enough for accumulating snow?

For the time being, temperatures are the trickiest part of the forecast. Both the NAM and GFS have been oscillating quite a bit on temperatures from run to run. This forecast is basically a blend of the two, but hedging toward warmer Monday highs and colder lows early Tuesday morning, since the models may be underestimating both extremes.

As the first storm passes mainly to our north early Monday, warm winds from the south/southwest - yes, another windy day around here, though less severe than today - likely push Monday highs into the 60s. In the wake of the first storm, winds start to come from the north by late afternoon or early evening and temperatures begin to fall, but may still be in the 50s to near 50 during the early-to-mid evening. So any precipitation that falls during the late afternoon through mid-evening should be light and just wet, not wintry.

The real action begins as precipitation potenitally picks up in intensity mid-to-late evening at the same time strengthening high pressure over the Upper Midwest/Great Lakes intensifies our cold winds from the north. That's when temperatrues should come crashing down, probably changing the rain to snow from north to south - there could even be a period of sleet during the changeover.

How much accumulation we see depends on how quickly temperatures get down to the mid-30s or lower, and how much moderate to heavy precipitation falls after that point. I say moderate to heavy precipitation because given how warm the ground will have been earlier in the day, light snow probably wouldn't be heavy enough to accumulate much except maybe on grassy areas, sidewalks and elevated surfaces. Lows early Tuesday morning could be as low as the mid-20s to near 30.

What does our winter weather expert Wes Junker say?

During the past 12 hours the NAM model has oscillated between a mostly rain-to-snow solution, to a sleet-and-snow but mainly snow solution, and then back to the rain-to-snow solution. The runs that have the surface low tracking farther north are warmer and have a rainier solution. The runs with the low track more to the south have a snowier solution.

This morning's NAM only gives D.C. about an inch of snow after a good deal of rain. This morning's GFS also stepped away from its all snow solution from last night to one with mostly rain with a little snow at the end. The 09Z sref plume diagram for D.C. is one that should give snow haters hope - about half the members show all rain and most that forecast snow end the precipitation quickly after the transition. To get an all snow solution, the track and timing of the second wave has to be almost perfect. The GFS model that was run at 1 a.m. this morning had such a track. The latest GFS and NAM do not.

The most likely scenario is that there will be some rain at the beginning of the event Monday evening and some snow toward its end as the temperatures really start crashing. During the north-to-south transition between rain and snow there will also probably be some sleet.

My best guess now is that we see more rain than snow in the D.C. area because another thread-the-needle storm track and timing are needed for us to get a significant snowstorm. However, until the models show more run-to-run consistency, last night's snowier solutions can't be completely ruled out.

Bottom line for now:

There's a good chance we'll see precipitation between late Monday afternoon and early Tuesday morning. It almost certainly starts as rain and should be light through mid-evening Monday. Chances of moderate to heavy precipitation increase mid-to-late evening and into early Tuesday morning, while at the same time plummeting temperatures should change the rain to snow with a period of sleet possible during the changeover.

Accumulation scenarios range from little to none; to a minor accumulation mainly on grassy areas, sidewalks and elevated surfaces; to a few slushy inches even on roads, especially untreated ones, that could impact the Tuesday morning commute.

It's too early to get into the details of possible differences between northern/southern/western/eastern portions of the area, other than to say that northern sections might have a better chance of accumulating snow than southern sections, since it'll be colder to the north first. Then again, there's also that chance that the best precipitation (moderate to heavy) takes more of a southerly track.

By Dan Stillman  | February 19, 2011; 4:00 PM ET
Categories:  Latest, Snow Lover's Crystal Ball  
Save & Share:  Send E-mail   Facebook   Twitter   Digg   Yahoo Buzz   Del.icio.us   StumbleUpon   Technorati   Google Buzz   Previous: Forecast: Hazardous winds raging across region
Next: Wind advisory through midnight

Comments

The National Christmas Tree is still up?!?! It's FEBRUARY!!!!!!!

Posted by: R617 | February 19, 2011 2:16 PM | Report abuse

I believe it is the tree planted on the Ellipse in 1978.

Posted by: johnslau | February 19, 2011 2:25 PM | Report abuse

Yeah, the National Christmas tree, near the white house, is a permanent tree. With roots. It just gets decorated for Christmas. The CAPITAL Christmas Tree, at the Capital, is a cut-down tree that is removed after Christmas.

Posted by: megamuphen | February 19, 2011 2:46 PM | Report abuse

Sooooooo...what y'all are saying is that most likely, we will get a slushy 1 - 3"??

rats.

I'd rather have a sunny day than that. If it's gonna snow, I want it to be fluffy & powdery, not wet & slushy.

1" of slush is as bad as cold rain in my opinion.

Maybe, now, we should all just accept the fact that we won't see anymore appreciable snowfall this winter :-(

But hey, there are only 284 days left until next meteorological winter begins!! ;)

Posted by: BobMiller2 | February 19, 2011 3:03 PM | Report abuse

My prediction for tuesday:

4-6 inches in dc with 6-8 inches to the north and west. Kids, your having a 4-day weekend because most schools will likely close Tuesday.

Posted by: SNOWLUVER | February 19, 2011 3:03 PM | Report abuse

megamuphen: "Yeah, the National Christmas tree, near the white house, is a permanent tree."

You mean "was" a permanent tree with roots!

Posted by: petworthlad | February 19, 2011 3:03 PM | Report abuse

Again, I REALLY despise the wind.

As far as impacts go this winter, today is second only to Commutageddon in my opinion.

Been a bad day everywhere.

Posted by: ThinkSpring | February 19, 2011 3:13 PM | Report abuse

@BobMiller2

What you say is certainly possible, but it's a bit early to commit to a "most likely" scenario. Maybe tomorrow we'll be able to do that, if models start to show more agreement and run-to-run consistency. -Dan, CWG

Posted by: CapitalWeatherGang | February 19, 2011 3:30 PM | Report abuse

Wow. If you look at the traffic cam posted in the update on the last post, you can see cars driving THE WRONG WAY on 95 to go back to the exit before the backup (since 95 is now closed, they can do that!)

Posted by: megamuphen | February 19, 2011 3:57 PM | Report abuse

Is I95 closed in 3 different spots? That's what the traffic map seems to indicate. All due to brush fires.

What an awful day.

Posted by: ThinkSpring | February 19, 2011 4:16 PM | Report abuse

even if it does actually switch over to snow, which im doubtful, but if it does, its gonna be a wet snow and not very much of it imo, because the bulk of the precip will fall before the "transition" (might) happens. And that lil bit of (possible but unlikely) wet snow will not amount to much, except maybe on grass. Kids should def not expect a snow day out of it, that is for sure.

Models will come around prolly monday afternoon and this will be a minor (couple of wet flakes) non accumulating threat at BEST for the DC metro area or all rain changing over to nothing at all which seems more likely imo.

I still think all met outlets have made too much of a big deal of this. I mean, every met in DC is throwing out every single option that could happen. Snow/rain/sleet/nothing/around an inch up to 3 inches, LOL :/

In the end it will have been all for nothing, imo of course. No way we go from 60s (poss 70s) daytime to accumulating snow that night.It can happen but in this case it will not happen, mark my words.

Posted by: KRUZ | February 19, 2011 4:19 PM | Report abuse

Wow - glad I'm out of town for the weekend (only Annapolis) staying at a lovely home and happy I don't need to go anywhere!

I'm with KRUZ - I've seen it where it's snowed one day and then gotten into the 60's the next - but not the other way around. I say the ground will be too warm to support snow.

Posted by: MKoehl | February 19, 2011 4:33 PM | Report abuse

It has smelled like smoke in my house all day (and outside). I guess brush fires somewhere nearby. I really don't like high winds.

Posted by: nolagirl67 | February 19, 2011 4:53 PM | Report abuse

The 18z NAM is a bit disappointing for snow lovers...a little warmer with most preciptation to the south. Looks like little to no snow with this solution. Let's go GFS!

Posted by: dsnowman | February 19, 2011 4:54 PM | Report abuse

Went to Glen Manor Vineyards today near Browntown and could see smoke plumes from a wildfire near/in Shenandoah National Park.

Posted by: spgass1 | February 19, 2011 4:54 PM | Report abuse

The 18z NAM is in and the GFS will be coming in shortly.

I think it's best we all give up hope at this point. Here's the latest output from the NAM:

1 AM Tuesday: http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/nam/18/images/nam_pcp_060l.gif

7 AM Tuesday: http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/nam/18/images/nam_pcp_066l.gif

Total qpf: http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/nam/18/images/nam_p60_084l.gif

Clearly, if there will be any further changes, they will be for the worse (less snowy) and not for the better.

This run puts out no more than maybe, I stress, maybe 1-3" at best with a late precip changeover.

I'm afraid I'll have to concur with KRUZ & MKoehl on this one - - it's looking like a complete miss/non - event.

NewsChannel8's 5 pm news (the only weekend local news at 5pm) is coming on now, so I'm going to go see what Steve Rudin has to say about the Tues. snow chance.

Posted by: BobMiller2 | February 19, 2011 5:04 PM | Report abuse

Both the 18Z gfs and NAM forecast a brief changeover with most of the precipitation falling as snow. The lone hold out for more snow is the 12Z euro. I think we see flakes but don't see much potential for accumulations but will offer a technical analysis tomorrow as we're still 54 hrs from the event.

Posted by: wjunker | February 19, 2011 5:12 PM | Report abuse

wes,
unfortunately, don't you mean most falling as RAIN?

Posted by: walter-in-fallschurch | February 19, 2011 5:18 PM | Report abuse

A major error, I meant to say the 18Z GFS and NAM have most precipitation falling as rain. I wish I could delete the previous post. I think we see a few flakes but don't see much potential for accumulations in the dc area. Hope I didn't get Bobmiller2 and Walter too excited.

Posted by: wjunker | February 19, 2011 5:18 PM | Report abuse

hahaha... wes, not that i was just checking the 18z gfs as it was coming out or anything, but i knew the darned thing had shown a late change-over.

do these things generally keep trending one way? or do they "wobble" back and forth? is this storm "getting away" from us? or could it "come back"? you mentioned the euro being the "lone holdout", and ian pointed out the euro's better "verification" statistics. can you elaborate on what the euro shows snow-wise, and why you're going gfs/nam over euro?

Posted by: walter-in-fallschurch | February 19, 2011 5:33 PM | Report abuse

With extremely dry cond. it would be great if can at least get some rain. Chances 4 anything more than 1-2" of wet snow is just a tad above 0. I'm offically throwing in the towel on getting any decent snow till next winter. Thinking that we can get a lot of snow Monday pm -Tue am is truly wishcasting. Besides, with temps in the 50's Wed-Fri. anything that falls will quickly melt.

Posted by: VaTechBob | February 19, 2011 5:48 PM | Report abuse

No one seems to want to talk about it, but the 18Z GFS seemed to be showing a brief period of snow or sleet tomorrow (Sunday) evening. Nothing major, but it would be something if it snowed Sunday evening, was 70 degrees on Monday, then snowed again Monday night.

Richmond was 5% relative humidity this afternoon with other stations as low as 3% in southern VA. Is that some kind of record?

Posted by: frontieradjust | February 19, 2011 5:49 PM | Report abuse

The EURO will verify. I don't understand why everyone is ignoring it. People aren't going to see this storm coming and its gonna smack them in the face just like commuteageddon did.

Posted by: SNOWLUVER | February 19, 2011 6:00 PM | Report abuse

Even if the EURO does verify its still going to be hard to get the snow because look at these temps the EURO shows on monday.

http://raleighwx.americanwx.com/models/ecmwfens/12zecmwfens850mbTSLPUS048.gif

Dont be surprised if we see mid 60s to close to 70 on monday!

Posted by: KRUZ | February 19, 2011 6:09 PM | Report abuse

VaTechBob,

Officially throwing in the towel, eh? I think I may do the same thing myself.

Posted by: BobMiller2 | February 19, 2011 6:12 PM | Report abuse

60s and 70s the day before don't worry me in the least. We are in a spring pattern, and we regularly get snow in spring patterns.

It's warm, temps crash, snow falls, we have one cold day, then we warm up and the snow melts.

This is a standard scenario for March snowfalls, and the pattern we are currently in is basically an early March pattern.

I'm not saying it's going to snow - it may or may not - but the temp on Monday has no real bearing on it.

Posted by: jahutch | February 19, 2011 6:24 PM | Report abuse

If record breaking temps near 80 this past week is apart of a "march" pattern than I'd love to see an April pattern in march ;)

If temps were in the 40s or 50s during the day monday I could see the possibility for snow that night but with each run of these models the daytime highs seem to go up more and more, just look at NWS temps. The one thing that is certain with all the models is that it will be warm monday and thats the only thing that is certain, according to the models. But now even the night time temps are starting to get tricky with the models as far as timing goes.

Posted by: KRUZ | February 19, 2011 6:53 PM | Report abuse

Wes, why do you discount the 12z Euro? Which model has performed the best this winter?

Posted by: mciaram1 | February 19, 2011 6:57 PM | Report abuse

mciaram1

My understanding of the EURO is it too is trending slowly to a less snowy outcome as well. Im sure by this time monday it will be just that, less snowy.

Posted by: KRUZ | February 19, 2011 7:14 PM | Report abuse

CWG: You guys do a great job, but who in the heck is responsible for these lousy teaser headlines?

Today, upon reading the meat of your analyses, the current reality seems to be that there is a minor chance of a few flakes, which, with the recent warming trend, makes it difficult to even imagine much of anything sticking even to grassy areas, even if the models might ultimately trend toward a more significant snowfall. Temperatures would have to fall like a rock - and black ice might be more of a concern than snowfall.

As an example, how about a more accurate and modest intro such as " After high winds and more warmth, could there be a few flakes in the future?". I think the winds experienced today end up being more of a story rather than a forecast of minor winter precipitation which only tempts snow lovers with a weather chimera.

Posted by: MillPond2 | February 19, 2011 8:54 PM | Report abuse

If you snow lovers dont get to see a couple of snow flakes mon/tues, it may be quite a while before you see them again...

Definitely wont be seeing any for the rest of February!
http://www.liveweatherblogs.com/myweatherlive/images/blogimage/610temp_new_small.gif

Warm temps on the way!!!!!

Posted by: KRUZ | February 19, 2011 9:04 PM | Report abuse

HPC tonight shows parts of the DC area fairly likely to get 4"

Posted by: spgass1 | February 19, 2011 9:16 PM | Report abuse

@KRUZ

Yes, unfortunately, you're probably right. But now that the snow chances are [just about] gone for the season, maybe I should join you in cheering for Spring weather!

There seems to be pretty good agreement among the models that Tues will not be a major winter weather event. 00z NAM should be coming in soon, but not expecting any major changes.

Maybe that means no more [snow] plowing for you ;-)

BTW, some of the daffodils and crocuses in my garden have started to pop up from under the soil! A sure sign that Spring is well on its way! :-)

Posted by: BobMiller2 | February 19, 2011 9:25 PM | Report abuse

My comment above should say this afternoon rather than tonight...

Frontieradjust, the GFS near surface temps look too warm tomorrow evening for accumulation, but I agree it would be interesting to see something...

00z NAM looks snowy to me for Monday night/Tuesday morning...

Posted by: spgass1 | February 19, 2011 9:37 PM | Report abuse

nice map there, spgass. one thing i'm enjoying about this storm is that, like the jan 26 storm, we're basically in/around the bulls-eye - and it's not gonna go up the coast and drop 20" on ny/boston again. i wonder what "guidance" that's based on. must not be the gfs or nam. looks to me like falls church is on the green line of that 40% zone. now if we can just get that 40% to verify.

KRUZ,
i can't get a look at that link you posted. it says something about "remote linking disabled".

Posted by: walter-in-fallschurch | February 19, 2011 9:43 PM | Report abuse

This snow storm is impossible. THE GROUND HOG DIDNT SEE HIS SHADOW!!!!!

Posted by: SNOWHATERRR | February 19, 2011 9:51 PM | Report abuse

00Z is already coming in warmer overall for the day monday. 540 line during the day monday has moved north of PA from the 18Z run and is now well into NY. Looks like things are trending warmer run by run. Could be mid 70s to near 80 on monday!

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/00/images/gfs_slp_036m.gif

And still looking warm enough for rain as the bulk of precip sits over us, 540 line has moved a little more north of DC compared to the 18Z run.

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/00/images/gfs_slp_054m.gif

Posted by: KRUZ | February 19, 2011 11:03 PM | Report abuse

If only we get the cold from the 0Z NAM (seems to be mainly snow) and the precip from the 0ZGFS (spits out a lot of liquid).

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/nam/00/images/nam_pcp_054l.gif

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/00/images/gfs_p24_060l.gif

Posted by: jms12 | February 19, 2011 11:09 PM | Report abuse

Always surprises me when folks want fluffy snow here...in the D.C. area we almost never get fluffy snow anyway!It's either sleet, freezing rain, or the wet stuff. Sometimes we get that "middle" snow that packs good with a silky texture. But these winds are dope...its freaking cold out there tonight! Cars were shifting out of lanes on the Beltway, winds were so bad.I've got a heavy steel storm door and the wind just hurled it open! Crazy.

Posted by: NewbreedSE | February 20, 2011 12:46 AM | Report abuse

"Printapons" are available for restaurants, recreation activities, entertainment, and drinks. Start saving with your coupons today

Posted by: lorijwilson | February 20, 2011 2:02 AM | Report abuse

The comments to this entry are closed.

 
 
RSS Feed
Subscribe to The Post

© 2012 The Washington Post Company