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Posted at 2:30 PM ET, 01/30/2011

Big Midwest snow looms, wintry mix & rain for D.C.

By Wes Junker

Late Monday through Wednesday, a complex storm system will throw a variety of precipitation types across the metro region.

The precipitation will probably start as a snow, sleet and/or freezing rain Monday night into Tuesday morning as models are now bringing some light precipitation into the area while holding in the cold air. This initial surge of precipitation well in advance of the main storm is likely to be heavier to our north toward the Pennsylvania border. Nonetheless, enough precipitation may fall for light accumulation of snow and/or ice.

Next chance of accumulating snow: Monday night
Probability of 1": 30-40%
Probability of 3" or more: 5%

On Wednesday, the storm will reform off the Atlantic coast but to our north suggesting that this storm will not have cold air to continue supporting frozen precipitation due to warmer winds coming up from the south. So rain is favored Wednesday morning. However, temperatures are predicted to be precariously close to freezing because low level cold air can sometimes hold on tenaciously. So areas especially west of the city still need to be on the alert in case the models trend colder.

While the metro region awaits a mix of precipitation, the storm evolution and intensity promises to produce a major, possibly historic snowstorm for parts of Missouri, Illinois (including Chicago), Indiana and Michigan.

How much precipitation are we talking about?

Systems that track towards the Ohio Valley and then reform off the coast to our north often produce less precipitation than the models forecast as the initial surge of precipitation is to our north and west as most of the upper level energy is well west of our area. So for the frozen part of the storm (Monday night and Tuesday morning), we probably wouldn't be looking at more than an inch or two of snow and/or a light glaze of ice.

For the second half of the storm (Tuesday night and Wednesday morning), when the secondary storm off the coast starts developing and the front approaches, the heaviest precipitation also often falls to our north and west. However, in this case, both the GFS and NAM models run with data from 1 a.m. and again at 7 a.m. predict between 0.50 and .75 inches of liquid over Washington with heavier amounts to the north towards the Pennsylvania border. That doesn't seem too far fetched in view of the strong upper system that will be pressing east across the area.

Tomorrow we'll provide zone maps with what to expect by region...

Could there be surprises from this storm?

Yes, it's still possible that temperatures could trend colder leading to more freezing rain than we are now anticipating. Another possible surprise could come with the cold front in the form of thunderstorms/convection. Both the NAM and GFS are forecasting strong upward motion with the cold front and are their forecasting soundings hinting that there is an outside shot that there could be a few cracks of thunder in the area. Having thunder twice in a span of a week during January would be highly unusual. For this storm though, we'd be getting rain-producing thunderstorms, not sleet or snow.

TECHNICAL DISCUSSION

The GFS, NAM and the latest European model all predict a period of light precipitation in association with warm air advection well out ahead of the main storm late Monday into Tuesday. The figure below shows the NAM precipitation forecast over the six hour period when the precipitation is expected to fall with temperatures below freezing.

020211-storm.gif
NAM model precipitation and temperature simulation for Tuesday morning.

For the second half of the storm (late Tuesday night and Wednesday morning), the NAM surface temperatures are precariously close to being below freezing especially west of the city. This makes a definitive call of whether the precipitation could stay freezing rain during the heaviest part of the storm a tough call. Cold air damming does tend to hold on longer than forecast by the models.

However, when precipitation really is falling intensely during marginal freezing rain events, the freezing rain process at the surface releases latent heat. That's the reason farmers spray oranges during cold outbreaks in Florida. The latent heating usually then warms the surface enough to keep subsequent heavy rain from freezing unless the cold layer is deeper than is currently shown on the models. We'll be watching the cold layer near the surface closely over the next two days for any colder temperature trend.

020211-sounding.gif
Forecast sounding (from NAM model) for Frederick, Md. Wednesday morning.

The forecast sounding from the NAM (see to the right) for a point near Frederick, Maryland illustrates the forecast dilemma. Note first that the surface temperature is right at or slightly above freezing. The temperatures in the warm layer (at around 5,000 feet) are 8C or around 45 or 46 F - warm enough to melt any snow and warm the rain drop enough to keep it from becoming supercooled as it falls through the very shallow layer of cold air near the surface even if the temperature was at or a degree below freezing.

Of even more import is the area of the sounding between the two blue lines. Note that the green temperature line tilts to the left more than the curved dashed lines on either side of it. That's a clear signal of convective instability. The NAM is predicting elevated convection may be embedded in the band of precipitation that will be crossing the region Wednesday. This morning's GFS was less bullish about the prospects for convection but does show an elevated unstable layer but much higher in the atmosphere than shown on the NAM. It's not clear that the GFS would support convection.

While the GFS is not as emphatic about the potential for convection, both models show strong upward motion across the area suggesting that a period of moderate to heavy rainfall with the front is a good bet sometime Wednesday morning.

midwest-020211.gif
Liquid equivalent precipitation forecast through Wednesday night forecast by the NAM model - where snow is possible.

The real story with this storm will be blizzard conditions that are likely to develop over parts of Missouri, Illinois, Indiana and Michigan where snowfall amounts could be in the 1 to 2 foot range in places. The exact location where the monstrous snowfall totals will occur depends on slight variations in track to the north or south. This NAM displays a plot of the liquid equivalent (above) that falls as snow during the entire 12Z run. Note the stripe of greater than 2.00 inches or liquid across northern Missouri into Illinois. The forecast for Chicago was 2.48" of liquid equivalent all falling as snow. Assuming a 10-1 ratio, a typical but conservative ratio for the very wettest storms and you'd have over 2 feet of snow.

The 12Z GFS is slightly less aggressive but still suggest the potential for someone to get over 18 inches of snow. D.C. snow lovers: live vicariously. This is going to be one monstrous storm.

In summary, while we think the bulk of the precipitation for DC and points east will fall as rain. The precipitation probably will start as snow, sleet or freezing rain Monday night and early Tuesday morning. Then we get a lull, and the next shot of heavier precipitation that appears slated for late Tuesday night into Wednesday probably as rain except possibly to our north and west. However, the models sometimes trend colder in these type of events so don't completely let your guard down especially if you live north and west of the city where the cold air may hold in longer near the surface.

Friday and Saturday snow threat?

The models are showing another threat for rain or snow for the Washington area toward next Saturday. The European and GFS models bring a low across the south and up the coast. The latest runs suggest temperatures may be too warm for snow - but it's a close call. The storm track would need to thread the needle in a perfect spot for snow for us as cold air is scarce. There isn't much skill at such long time range forecasts so much can change about the storm.

By Wes Junker  | January 30, 2011; 2:30 PM ET
Categories:  Latest, Winter Storms  
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Next: Forecast: Light wintry mix tonight

Comments

Tuesday morning and Wednesday morning in Fairfax. Are you saying there will be freezing rain two mornings in a row? If not, which morning has the better chance of freezing rain?

Posted by: rwalker66 | January 30, 2011 2:40 PM | Report abuse

Tuesday morning has a much better chance. We think wednesday morning that the precipitation will be rain.

Posted by: wjunker | January 30, 2011 2:45 PM | Report abuse

@rwalker66

Freezing rain is more likely Tues am than Wed am... Just a slight chance it stays cold enough for freezing rain Wed am.

Posted by: Jason-CapitalWeatherGang | January 30, 2011 2:47 PM | Report abuse

I meant to say, we think Wednesday will probably be rain, not freezing rain but that points to the north and west still should be watching their temperatures as surface temperatures could end up being colder than the models are forecasting.

Posted by: wjunker | January 30, 2011 2:48 PM | Report abuse

"The European and GFS models bring a low across the south and up the coast. The latest runs suggest temperatures may be too warm for snow - but it's a close call. The storm track would need to thread the needle in a perfect spot for snow for us as cold air is scarce."

Hmmm...is it just me or does that sound just like last week's snow?

I'm ready for more snow. Let's hope it threads the needle this time. Is that too much to ask?

Also, it would occur late in the week, so hopefully it won't affect commuters too much.

Posted by: BobMiller2 | January 30, 2011 2:52 PM | Report abuse

Thank you for the update. Sounds like a couple of possibly scary morning commutes coming up. Regarding possible cold hanging on "north and West" - could you please be a little more specific? Are IAD, Reston, Sterling North and Manassas West? Or is it WVa and I81?
Sounds like we'll have to check back often, and we may not know until the precip falls.
Thanks again

Posted by: Restondad2 | January 30, 2011 2:53 PM | Report abuse

this update left me 10 times more confused.

Posted by: RJ16 | January 30, 2011 2:53 PM | Report abuse

Mixed precip followed by a cold rain! I'll take it.

Posted by: Jimbo77 | January 30, 2011 2:56 PM | Report abuse

@CWG! school cast for MCPS Tueday = 3 apples?

Posted by: RJ16 | January 30, 2011 2:58 PM | Report abuse

Has Fairfax county closed their schools yet in anticipation of these storms?

Posted by: Axel2 | January 30, 2011 3:01 PM | Report abuse

RJ16, sorry, then I failed in my discussion. The bottom line is that Tuesday morning looks like there will be frozen or freezing precipitation through the morning rush hour, then we probalby gt a break in precipitation until late Tuesday night into Wednesday morning when temperatures are expected to be warm enough for rain across most of the area. However, it's still a tricky forecast especially out west of the beltway towards leesburg, Frederick. We think their temperature will rise above freezing but it is not a given. Sorry for causing confusion.

Posted by: wjunker | January 30, 2011 3:01 PM | Report abuse

@Restondad2

It's hard to pinpoint where the freezing line will be Wed a.m. Some of the models show around Frederick, others even N & W of that. But the models can be too warm in these scenarios. We'll have a better sense tomorrow.

Posted by: Jason-CapitalWeatherGang | January 30, 2011 3:02 PM | Report abuse

So Tues early could be trouble...and Weds morning we get all the salt/sand washed away and cleaned up...right in time for Fri/Sat..grin. Guess I can skip washing the car this week. However...my friends in Chicago...well...hope they lay in a lot of pizza...!

Posted by: Hiflyer | January 30, 2011 3:14 PM | Report abuse

@Hiflyer

You got it :) But we gotta watch those temps Wed a.m.

Posted by: Jason-CapitalWeatherGang | January 30, 2011 3:19 PM | Report abuse

one thing I left out of my discussion is that somewhere in the midwest just south of the band of heavy snow there probably also will be a band of very heavy freezing rain that could lead to power outages. This is going to be a big deal for people in the Midwest.

Posted by: wjunker | January 30, 2011 3:19 PM | Report abuse

@ WES, your explanation was great. Thank you for the clarification! Oh boy... Tuesday's rush hour could be bad.

Posted by: RJ16 | January 30, 2011 3:19 PM | Report abuse

CWG - Thank you. Sounds tricky, huh?
Since I am the ultimate procrastinator, I found your post helpful. You basically just told me to, "Catch up on the important errands tomorrow, as Tuesday morning might be a time to stay off the roads."
I am fortunate to have that flexibility, and I don't take it for granted. I will be back out there commuting in the years to come. Right now, I can help by staying off the road during poor driving conditions when I don't HAVE to be out there in the first place!

Posted by: holly6 | January 30, 2011 3:36 PM | Report abuse

Does it look right now like the frozen precip going into Tuesday morning will be bad enough to affect the morning commute or will there not be enough of it?

Posted by: Dylan0513 | January 30, 2011 3:40 PM | Report abuse

Same question here. Will schools and buisness be closed or delayed tues am you think?

Posted by: BradFinWoodbridgeVA | January 30, 2011 3:47 PM | Report abuse

@BobMiller2
Next weekend's storm does look a lot like last Wednesday's snow storm as far as what the models (GFS and ECMWF) were doing with it in the medium range. The southern energy that forms the coastal storm has been getting pushed further and further into the future as it lingers over the Southwest/Southern Plains longer. I wouldn't be surprised if the bulk of the storm ended up coming through late Sunday or into Monday. Still too early to call the actual track or temps, but the Wednesday storm had similar (almost exactly the same) temperature issues we're seeing in the models now for this weekend's storm.

Posted by: MarkEllinwood | January 30, 2011 3:48 PM | Report abuse

BradF, schools around here tend to be very liberlin there closing around here, but Precip Monday night still looks to be very light. If I had to venture a forecast, I'd say delays are possible, but closings would be unlikely.

Posted by: Brian-CapitalWeatherGang | January 30, 2011 3:57 PM | Report abuse

In the 18z NAM the 850mb is precariously close to the area 72 hours out when there's a lot of qpf spreading into the area. I'd say that definitely needs to be watched.

Posted by: Dylan0513 | January 30, 2011 3:57 PM | Report abuse

Amateur NAM, GFS, etc. Readers. Since CWG can not always be on the computers updating us, can you guys look at the models and update us that rather not deal with the readings? Thank you.

Posted by: RJ16 | January 30, 2011 4:03 PM | Report abuse

CWG - Thank you. Sounds tricky, huh?
Since I am the ultimate procrastinator, I found your post helpful. You basically just told me to, "Catch up on the important errands tomorrow, as Tuesday morning might be a time to stay off the roads."
I am fortunate to have that flexibility, and I don't take it for granted. I will be back out there commuting in the years to come. Right now, I can help by staying off the road during poor driving conditions when I don't HAVE to be out there in the first place!

Posted by: holly6 | January 30, 2011 4:25 PM | Report abuse

The 18Z nam is quite a bit colder in the low levels than its previous run and now places like Frederick, MD look like they would have freezing rain wed morning. That suggests others closer in to the city may also have to watch temps closely. We'll update and have a map tomorrow.

Posted by: wjunker | January 30, 2011 4:25 PM | Report abuse

I'm not seeing too many changes with the 18z NAM. It really looks like the midwest will get hammered from this. The qpf over St. Louis is 2.0 - 2.5. Chicago really appears to be in for it: 17 -25 inches looks likely.

I think we're going to have to get lucky for this **potential** weekend storm. It would have to thread the needle and we would need cold air. @MarkEllinwood makes some good points. I would agree that the bulk of the storm will probably get pushed back into the Sunday/Monday time frame.

Finally, DCA and IAD's average snow totals still stand at 16.6 and 22.8". Does anyone know if these have been adjusted after last year's record snowfalls? Also, are those averages for the past 10 yrs, 20 yrs, or do they include all the snow that has fallen ever since records have been kept?

By the way, I also thought it was worth mentioning that the blizzard of '66 struck on this day, 45 yrs ago, dumping 20"+ across the region. I haven't seen anyone post anything about it today.

I found some very interesting archived footage on youtube that someone took in SE DC during the blizzard of '66:

http://www.youtube.com/watch?v=-7KOvJP5u2o

Posted by: BobMiller2 | January 30, 2011 4:28 PM | Report abuse

How far to the north will this be a bigger problem? And how long will the icing hang on? I'm concerned about flying via Philly on Wednesday afternoon/evening. Doesn't look like it will be a huge problem here, but how about up there?

Posted by: breitz | January 30, 2011 4:37 PM | Report abuse

Maybe I missed it, but I dont see a time estimate of the precipitation start on Monday night. Are we talking rush hour? 9pm? around or after midnight?

Thanks!

Posted by: apeirond | January 30, 2011 4:50 PM | Report abuse

The temperature map posted, shows the DC area in the 30 degree range. I have to assume that can mean 30-39 degrees? Is there a way to decipher where in that range temperatures will be, do the broken lines mean anything as well?

Posted by: TheMot | January 30, 2011 5:00 PM | Report abuse

What a depressing SLCB this is.
Sounds wet & sloppy & potentially dangerous for those caught in an ice zone. Out in western Fairfax, that would maybe be me.

Unless you guys tell me otherwise I'm on yellow weather alert status starting tomorrow afternoon. Incoming ice not to be messed with.
Sounds like the odds of this being a decent snow event for the area are close to nil. All rain means no pain for me on this one.

Posted by: FIREDRAGON47 | January 30, 2011 5:15 PM | Report abuse

What do you think the outlook is for a flight from DCA to Chicago Thursday night? Will O'Hare be cleared out 24 hours post-blizzard? Should I park at DCA instead of taking the Metro so I can have a place to sleep overnight?

Posted by: whoawhoawhoa | January 30, 2011 5:29 PM | Report abuse

I'm praying for rain in this next one. Please no ice!

Posted by: HappyArmyWife | January 30, 2011 5:32 PM | Report abuse

Dang. People ask real specific questions. In that case, CWG should I wear my northface or Columbia jacket on Tuesday. Tie or no tie?

Posted by: RJ16 | January 30, 2011 5:33 PM | Report abuse

Wes, thanks for the detailed analysis - always an interesting read... My question for you: you guys have talked about the northern I95 corridor getting slammed during most of the storms this past season, but it looks like it's out west that will be getting the snow this time, with a jumble of precip forms in the east (sad face). We are planning a drive up to NH on Wednesday - should we go early (Tues?), stick with the plan for Wed, or postpone our drive until Thurs? Or is it still too early to plan?

Posted by: Myndiera | January 30, 2011 5:44 PM | Report abuse

@whoawhoawhoa

This isn't an advice column, but why not just get a hotel room near the airport if all else fails?

Posted by: BobMiller2 | January 30, 2011 5:45 PM | Report abuse

It's as if those environazi climate freaks are right. They said that there would be more frequent, and more intense storms. And there are. The last decade has been a progressive series of historically big storms, in DC, elsewhere in the U.S. and around the world. But it's too cold to be global warming.

Posted by: blablabla | January 30, 2011 5:50 PM | Report abuse

Ps - not *really* asking for advice, I guess my question was really: what is your take on what kind of precipitation will be falling along the eastern seabord?

Posted by: Myndiera | January 30, 2011 5:51 PM | Report abuse

It's as if those environazi climate freaks are right. They said that there would be more frequent, and more intense storms. And there are. The last decade has been a progressive series of historically big storms, in DC, elsewhere in the U.S. and around the world. But it's too cold to be global warming.

Posted by: blablabla | January 30, 2011 5:58 PM | Report abuse

I'm an occasional reader of CWG, so I'm sure I missed this somewhere before, but can someone give a brief idea of the difference between the European and GFS models? All I know, from their names, is that they are apparently two different models :).

(And as long as I'm writing, can I add a plea to everyone who posts in the talkbacks after Washington Post articles- just because Twitter uses an @-sign to precede users' names, is it really necessary that everyone use @-signs in front of user names everywhere else online? It's really ugly-looking, and, amazingly enough, not everyone uses Twitter. Thanks. :)

Posted by: yrral | January 30, 2011 6:02 PM | Report abuse

yrral -

Thank you thank you thank you thank you!!! Somebody said yesterday it's "is widely accepted usage on internet forums." It wasn't until stupid Twitter came around and like you said, we don't all use that rediculous please pay attention to me forum.

Posted by: TheMot | January 30, 2011 6:18 PM | Report abuse

No chance that Moco or Fairfax open on time if the commute will be even marginally affected by freezing rain. 100% chance for school delay on Tuesday.

Posted by: heatherdc1980 | January 30, 2011 6:19 PM | Report abuse

No chance that Moco or Fairfax open on time if the commute will be even marginally affected by freezing rain. 100% chance for school delay on Tuesday.

Posted by: heatherdc1980 | January 30, 2011 6:20 PM | Report abuse

@breitz

Not a likely problem for Philly Wed afternoon from a wintry precip standpoint. Delay poss due to rain more likely.

@Myndiera

TO me, NH looks snowy Wed afternoon and night with also a little light snow Tues afternoon.

@yrral

We should probably do a model 101 post at some point. But basically the GFS is a weather model run by NOAA and the Euro is a model run by the European Center for Medium-range Weather Forecasting (ECMWF). You can google the ECMWF models and GFS models for more background for time being. Sorry about the @symbols - it's just the symbols we've adopted in the digital age. It's not only Twitter, but also email that uses them.

Posted by: Jason-CapitalWeatherGang | January 30, 2011 6:21 PM | Report abuse

CWG'ers - you considering doing a zone forecast for this early week storm sometime tomorrow? Sounds like it might be handy, given that we're going to be looking at widely-ranging conditions (again) in areas N/W of the city vs. points S/E...

Posted by: ToBeBlunt | January 30, 2011 6:25 PM | Report abuse

blablabla:

Global warming doesn't mean that everywhere will be immediately warmer. Weather is far more complicated than that.

However, you will find that 2010 was in fact one of the warmest years on record, and most of the top ten warmest years happened in the last decade.

http://www.accuweather.com/blogs/climatechange/story/44338/record-warmth-confirmed-by-add-1.asp

Posted by: celt1 | January 30, 2011 6:25 PM | Report abuse

@Jason-CapitalWeatherGang

What are your thoughts (or any of the CWG guys thoughts) on the drive from DC to Caroll County, MD after the CAPS game Tuesday night? Safe or unsafe?

Posted by: DLO1975 | January 30, 2011 6:26 PM | Report abuse

FYI folks, FX County schools are already closed Monday and Tuesday for a planned end-of-semester break. Happens every year end of January.

Posted by: bodypolitic1 | January 30, 2011 6:43 PM | Report abuse

For Harpers Ferry, the good news is that there's little confusion or doubt about what's coming. The bad news is that it looks like three days and nights of ice, in one nasty form or another.

So instead I'm watching the colors shift on the HPC 3-day outlook. Blue last night, shifted to green (drier! better!) this a.m., now back to blue. Darn.

Posted by: tinkerbelle | January 30, 2011 6:48 PM | Report abuse

I agree with ToBeBlunt. A zone forecast would be very helpful.

Posted by: BobMiller2 | January 30, 2011 7:09 PM | Report abuse

@yrral's 6:02 p.m. post - If that's your biggest problem, you're having a pretty good day.

Posted by: waterfrontproperty | January 30, 2011 7:31 PM | Report abuse

The explanation of latent heat release matches what I see, in marginal freezing rain situations the temperature rises to 33 and sits there. The only exception is if there is arctic air to the north and a north wind (even a slight wind will do the trick). Then the rain might keep freezing.

The flipside of latent heat release is cooling from melting ice, so a lot of times they forecast 39 or 40 degrees during the cold rain phase but we hang at 33 here in the Valley provided there is a secondary low (even a small one) off the coast to hold in the cold air.

Posted by: eric654 | January 30, 2011 7:41 PM | Report abuse

Ugh, the vampire cloud is back.

Posted by: megamuphen | January 30, 2011 7:47 PM | Report abuse

Also, yeah, Twitter may have brought the @ signs into prominence, but they have really spread across other online mediums. I think it is the most concise way in a non-threaded comment section to respond specifically to one person.

Posted by: megamuphen | January 30, 2011 7:53 PM | Report abuse

RJ16 - umbrella and no tie

Posted by: holly6 | January 30, 2011 7:54 PM | Report abuse

Will be waiting for the zone forecasts here in Eastern PWC. Got lots of stuff going on, and this weather could easily throw a proverbial 'monkey wrench' into the plans in nothing flat!

If any of the 'model weenies' out there could venture a guess of the timeframe they think precip will start tomorrow (afternoon, before/after rush hour, bedtime, etc.) I know I'd sure appreciate it (in the short term).

Till then, all I can say is make sure you have a backup plan for whatever you're doing. If you're going to the midwest, count on delays. Although they are FAR better equipped to handle this than we are, 18 inches (or more) of snow is a LOT to deal with no matter where it is. COUNT on problems.

BradF-- Better be ready to switch your schedule on a dime this week for school, as PWC WILL change schedules if the frozen stuff hits. Our schedule at home has been back and forth more than a tennis ball in a bad tennis match!

Best of luck everyone! Be safe!

Posted by: southbridgemom | January 30, 2011 7:59 PM | Report abuse

See, BobMiller2, we *CAN* agree on some things... ;)

Posted by: ToBeBlunt | January 30, 2011 8:04 PM | Report abuse

megamuphen - see, that was easy

Posted by: TheMot | January 30, 2011 8:16 PM | Report abuse

The temperature map posted, shows the DC area in the 30 degree range. I have to assume that can mean 30-39 degrees? Is there a way to decipher where in that range temperatures will be, do the broken lines mean anything as well?

Posted by: TheMot | January 30, 2011 8:51 PM | Report abuse

@megamuphen, I prefer the monty python route: clouds with sharp pointy teeth!! Either way, not fun!

Posted by: kmill67 | January 30, 2011 8:55 PM | Report abuse

kmill67 - okay, I'm in no position to grant it, so I grant thee (as a hopeless Python fan) ToBeBlunt's personal Comment Of The Hour award. Read your comment and instantly pictured clouds screeching and rushing me from above, icicle teeth bared... :)

Posted by: ToBeBlunt | January 30, 2011 9:05 PM | Report abuse

YES to zone forecasts-- tomorrow midday...

Posted by: Jason-CapitalWeatherGang | January 30, 2011 9:13 PM | Report abuse

Any more NAM, EURO, GFS updates guys? Come on yo.

Posted by: RJ16 | January 30, 2011 9:15 PM | Report abuse

On several other sites, I'm seeing mention of a chance of freezing drizzle or light freezing rain tomorrow during the day, with highs only in the upper 20's in Loudoun.

Having gotten stuck for hours on the Dulles Toll Road twice in the past due to "surprise" ice events, I have PTSD now when it comes to situations like this.

CWG, are there going to be any issues tomorrow during the day??? I know tomorrow was supposed to be cold but isn't upper 20's a bit excessive?

Posted by: ThinkSpring | January 30, 2011 9:22 PM | Report abuse

NAM model is in enough to show this storm. If anything this stuff doesn't look like an issue around here. A fair amount of cold air here tomorrow, then pulls out north as moisture arrives Tuesday morning.
But I'm sure our TV mets will spin it to keep viewers. Rain in January is still "winter weather" after all.

Posted by: AndrewRockville | January 30, 2011 9:30 PM | Report abuse

Thanks for your tireless work this winter, CWG!

What time do you think the mix/ice will start Monday night (around Arlington and Vienna)?

Posted by: LAS1 | January 30, 2011 9:44 PM | Report abuse

NAM coming out as we speak. Too bad it only goes out 84 hrs. It would be nice to have something other than the GFS or Euro to look at for the late week storm. Still keeping my fingers crossed.

Back to work tomorrow...sigh...the weekend was nice while it lasted.

Posted by: BobMiller2 | January 30, 2011 9:47 PM | Report abuse

Henry Margusity from Accuweather: "The issue for the folks north of DC is the first wave that goes by Tuesday. If that is a little stronger, it will push the cold air all the way south of DC prior the heavy precip coming Wednesday AM. What that means is serious icing between southern New York and northern Virginia, including all the major cities."

Posted by: Dylan0513 | January 30, 2011 9:51 PM | Report abuse

So based on the NAM, what does it look like. We getting some ice or freezing rain tomorrow. Enough to disrupt morning RUSH HOUR?

Posted by: RJ16 | January 30, 2011 9:53 PM | Report abuse

the 00Z nam is back to a warmer solution for Wed, pretty much in keeping with the thinking in the original discussion.

Posted by: wjunker | January 30, 2011 9:58 PM | Report abuse

Wait CWG, but we're talking about Monday night into Tuesday morning...what are we going to get.

Posted by: RJ16 | January 30, 2011 10:03 PM | Report abuse

Wes- how much qpf exactly does the 0z NAM show for DCA for the Monday night into Tuesday morning period?

Posted by: Dylan0513 | January 30, 2011 10:08 PM | Report abuse

@RJ16

The NAM model shows very light mixed precip- sleet and freezing rain, maybe a little snow for Monday night (but less than inch, if any). We gotta process the other models before we update the forecast. Pretty much what we have here now is still reflects our thinking.

Posted by: Jason-CapitalWeatherGang | January 30, 2011 10:12 PM | Report abuse

@Dylan0513

It's super light... 0.04" overnight Monday through 7 a.m. Tues. If it's right, maybe a few flakes at first (little or no accumulation), then light sleet and freezing rain. Maybe just a light glaze and not a huge deal... though just a little ice can cause problems. Other models have shown a bit more...but this is looking to be a minor event

Posted by: Jason-CapitalWeatherGang | January 30, 2011 10:17 PM | Report abuse

Wes/CWG - I apologize if this has been covered before, but are we looking at significant surface winds during either of these two events? I am trying to put together my own PEPCast - winds > 5 mph + any sort of frozen precip that sticks to any surface, and we lose power for three days...
Just trying to figure out I need to go refill the generator tomorrow? :)

Posted by: vtavgjoe | January 30, 2011 10:17 PM | Report abuse

Dylan05, less than a tenth of an inch, very, very light.

Posted by: Brian-CapitalWeatherGang | January 30, 2011 10:22 PM | Report abuse

If it's indeed that light, it'll be interesting to see how the area reacts. Will Sterling issue an advisory? Will we see schools close? I honestly wouldn't be surprised if both happened.

Posted by: Dylan0513 | January 30, 2011 10:23 PM | Report abuse

Thanks ToBeBlunt! Comment of the hour AND one of my fav baseball players tweeted to me today...yep, it’s an awesome online Sunday.

Posted by: kmill67 | January 30, 2011 10:32 PM | Report abuse

@vtavgjoe

Unless, the forecast changes dramatically and Wednesday turns into a significant freezing rain event, I don't think you need to worry about outages with this storm. We're talking very light frozen precip Monday night, and mostly rain Wed when we get the heavy stuff based on current guidance. Could have some wind late Wed, but temps should be well above freezing then. Check back tomorrow and Tuesday.

Posted by: Jason-CapitalWeatherGang | January 30, 2011 10:33 PM | Report abuse

@Jason-CapitalWeatherGang,

Is it likely that flights landing at DCA Monday night (8-11pm) will face delays or cancellations with the ice?

Posted by: mpost27 | January 30, 2011 10:44 PM | Report abuse

@mpost27

I don't think so. Very light precip if any at that point. Airports can handle it.

Posted by: Jason-CapitalWeatherGang | January 30, 2011 10:48 PM | Report abuse

GFS looks to be showing a little more qpf than the NAM for Monday night into Tuesday?

Posted by: Dylan0513 | January 30, 2011 10:52 PM | Report abuse

Could you guysbe wrong at all about Monday night into Tuesday morning? Meaning, could we end up with a lot more ice than expected? Specially for us up in Damascus?

Posted by: RJ16 | January 30, 2011 10:55 PM | Report abuse

Jason--Glad to hear you all don't anticipate precip issues till after the 8-11pm timeframe tomorrow night. Will give most of us a chance to get home after work in a timely manner. And maybe, just maybe a chance to get errands done after work.

Here's hoping!!

Posted by: southbridgemom | January 30, 2011 10:59 PM | Report abuse

Yes, no commutageddon this week please!

Posted by: natsncats | January 30, 2011 11:08 PM | Report abuse

@Dylan0513

Yes-- GFS does show a bit more ice potential than NAM for Tuesday morning. Bottom line: Wes' forecast above is still valid- mix of light frozen precip Monday night & esp. Tuesday morning.

@southbridgemom

I'm not necessarily saying we're totally off the hook for Monday night - we may have some patchy light frozen precip that causes slick spots. I'm just indicating airports can probably handle the light rates of precip anticipated at that time without major disruptions - minor delays are certainly possible.

@vtavgjoe

Looking at the data, it appears Wed may turn quite windy. I don't think widespread power outage windy-but just wanted to give you a heads-up.

That's all the questions I can take for now...gotta get some work done and go to bed. Bottom line is that this is a minor event that may cause some issues mostly Tues morning but is nothing like last Wed. The models tonight tell us nothing earth shattering.

Posted by: Jason-CapitalWeatherGang | January 30, 2011 11:13 PM | Report abuse

"However, when precipitation really is falling intensely during marginal freezing rain events, the freezing rain process at the surface releases latent heat. That's the reason farmers spray oranges during cold outbreaks in Florida. The latent heating usually then warms the surface enough to keep subsequent heavy rain from freezing unless the cold layer is deeper than is currently shown on the models."

Does having some significant amount of snow on the ground diminish this effect?

Posted by: staticvars | January 30, 2011 11:34 PM | Report abuse

Jason -- oh no, no, no, no!! I know you all weren't saying we were off the hook for frozen stuff. I had asked earlier if anyone could venture an early guess as to when precip could start in the DC metro (and down towards my area) tomorrow. I was trying to get an idea how many alternate plans (if any) I needed to come with for commutes home, picking up the little guy from daycare, etc. I know that 3-5 flakes of snow, and about 2-3 sleet pellets will send this area into a tailspin. I also think this area will be quite sensitive after the fiasco last Wednesday PM, and the PM commute tomorrow could suffer as a result. Not for sure, but I wouldn't be surprised.

Posted by: southbridgemom | January 30, 2011 11:53 PM | Report abuse

It's sleeting NOW at the 301 Bridge. Really.

Posted by: waterfrontproperty | January 30, 2011 11:56 PM | Report abuse

Maybe radar is just showing a bunch a virga a little south of us right now, but it's making me nervous.
Am I going to wake up to a surprise glaze of freezing drizzle in Centreville? Is the last day of January 2011 ready to give us all one final boot to the bottom?

Posted by: FIREDRAGON47 | January 30, 2011 11:58 PM | Report abuse

@waterfrontproperty

Yes- there is a ribbon of light mixed precip in our extreme southern suburbs from west of Fredericksburg into Charles, southern Calvert and St. Mary's counties. Should continue east and end over the next few hours.

Posted by: Jason-CapitalWeatherGang | January 31, 2011 12:15 AM | Report abuse

BobMiller2: The annual snowfall averages (and all other averages) will be updated by the NWS this year to reflect weather over the past 30 years only (1981-2010), as that is their policy. They don't use the entire period of record because that would tend to obscure climate change too much.

Posted by: Don-Capital Weather Gang | January 31, 2011 12:28 AM | Report abuse

Tuesday will probably be a mess one way or another. That is quite z chunk of cold air that is going to get here ahead of the pricip, so whatever falls Monday night or Tuesday is going to stick on the roads.

It seems unlikely that temps on Tuesday will get get to freezing.

Hopefully by Wednesday, the cold air will be pushed out. There could be a major ice storm not far north of DC, probably PA will get hammered. Plenty of more snow for New England.

Posted by: frontieradjust | January 31, 2011 12:32 AM | Report abuse

@whoawhoawho

This is part of the weather warning for Chicago:

THE STORM SYSTEM WILL AFFECT A LARGE PORTION OF THE SOUTHERN GREAT LAKES... MIDWEST AND OHIO VALLEY REGIONS. ANYONE WITH TRAVEL PLANS TUESDAY AND WEDNESDAY... INCLUDING THOSE TRAVELING THROUGH CHICAGO OHARE AND MIDWAY AIRPORTS... SHOULD CONTINUE TO MONITOR LATER FORECASTS REGARDING THE DEVELOPMENT OF THIS WINTER STORM.

Nothing about thursday, but according to the snow total map from WGN, we are in the 20-25 inch range. If we exceed 23 inches, that will be a record.

We handle snow pretty well out here, but my guess is you're in some trouble. 1. you're flying through O'Hare, you'd be delayed even in good weather, 2. this could be a historic storm.

If there's any consolation, the weather should be out of here by then and anyone who flies into O'Hare in the winter sees the lineup of plows at the ready.

If there is one more thing to add... as someone who went to UMD, I scheduled my flight the monday after finals, 2 days after the december storm in DC. There is certainly a better than average chance O'Hare will be ready for Thursday with snow stopping Wednesday night...

I will finally, again caution, that we may never have seen a storm this big in Chicago... ever.

Posted by: mjterp | January 31, 2011 3:28 AM | Report abuse

Have today's models suggested any changes to what we should expect in areas of Fairfax County during the next couple of days? Have the models shown whether we will see lower temperatures on Wednesday, or higher snow accumulations?

Posted by: deanna1203 | January 31, 2011 4:52 PM | Report abuse

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