Major snow storm expected: Capital Weather Gang forecast

Jan 26, 2011

Jason Samenow, chief meteorologist for the Capital Weather Gang, will be online Wednesday, Jan. 26, at Noon ET to discuss the latest forecast information about the oncoming snow storm.

Thanks for joining me for today's chat.  The heavy late afternoon/evening "thump" of snow we've been talking about for a couple days is looking like it will materialize.  The Weather Service has expanded the Winter Storm Warning over most of the metro area and is now calling for 5-10" of snow.  Snow will fall very heavily between 4 and 8 p.m. tonight with dangerous travel conditions.

Already seeing some white stuff on the ground? Send your pix to our Winter 2011 snow gallery!

I just wanted to take this opportunity to thank the Capital Weather Gang for taking weather forecasting to a new level. I appreciate getting a better understanding of the probabilities and complexities in a weather forecast. As someone that has been responsible for forecasting gasoline prices in the past, I understand how uncertainty plays a major role and your group does an excellent job discussing the uncertainties, even if not everyone hears it! I tell everyone that this is the first place they should go for a weather forecast. Keep it up!

Thanks so much for the nice feedback.  We do our best to provide as much information as possible to help everyone best understand the forecast and the science behind it.

I'm getting nervous about this latest snow forecast. Do you think the Feds will make a call early tomorrow morning to offer the telecommute option for those working under a telecommuting agreement? I sure hope so. Last year, without this option, I really suffered during those two big snowfalls.

The Federal government is taking today's snow threat very seriously and has smartly dismissed Federal workers two hours early.  Federal Eye Blog.

I live in Alexandria but work in Dahlgren (King George County). These areas seem to have very different forecasts for this storm, so I'm not sure when to leave work in order to avoid heavy snow on my drive home. When is heavy snow expected to start in Alexandria? In Waldorf?

Precip should get going in Alexandria around 2 or 3 p.m. possibly as rain, but changing to snow by 4 or so.  It may start around the same time in Dahlgren or a little later - but probably won't change to snow until after dark.  I'd advise leaving as early as you can - because conditions will rapidly deteriorate as you head toward Alexandria this evening.

It seems like one element of snow for us (excluding last year's mega-storms) is usually some warm air coming up from the south. Hence, our snow tends to melt off in the next few days. Is that generally true of our normal ~6" falls?

Sometimes, we get a warm-up after a snowfall...but sometimes it gets colder too or stays the same.  I don't think you can make a generalization about it.

We are currently planning to drive from Alexandria to just north of NYC on Friday morning (returning on Sunday). Will this storm/any after-effects make this difficult/impossible?

You should be ok by then. There will be time for crews to have cleared the roads.

What are the chances that the federal government will close tomorrow? I work for a trade association in downtown D.C. that follows the snow policy of the fed gov and I really don't want to have to commute in the snow if it turns out to to be as bad as the forecasters are predicting.

If I had to guess, this won't be an extreme enough of an event for the gov to close, but an unscheduled leave policy or delayed opening possible.

Is the accumulation forecast for central Virginia (5 to 10 inches according to NWS) still accurate? It has been doing nothing but drizzling freezing rain here all day. It doesn't seem to be a great base on which to accumulate the white stuff.

Most of the snow is going to fall fast and furious during a six or so hour window - probably between about 1 and 7 p.m. in Central Va. - and 3 to 9 p.m. or so in the DC metro region.  The snow may briefly begin as rain.

Greetings from Frederick, Considering this is expected to be a very heavy snow and could accumulate extremely quickly, should we be worried about roof collapses?

While this will be a heavy/wet snow - especially at the onset - I'm thinking and hoping amounts won't be high enough for roof collapses.  There may be issues with trees limbs and power lines, however.

I am scheduled to fly into Dulles at 4pm tomorrow. Should I expect delays/cancellation? Thank you.

Everything should be returning to normal by that time tomorrow.  Have a safe flight.

How will the storm affect areas north of DC? More or less accumulation anticipated?

We're thinking 4-8" + just about everywhere - but with amounts tending higher north and west of town.  Some places north of D.C. already got a couple inches this morning - especially toward Baltimore.

If the snow ends around midnight, I really shouldn't go out with my snow blower then to clear my driveway since it's pretty loud. But, if I wait until morning, will my driveway have frozen over with ice? Help me decide between using a shovel at midnight and using my handy machine ~10 hours later.

It's always a good idea to shovel early and often - especially with heavy wet snow that will compact and refreeze.

Any guidance on what we might expect up here in Delaware? We have some decent weather blogs out of Philly, but your coverage is so much better than theirs. We got a solid 3-4 inches of snow overnight and it doesn't appear to be getting rained away, so already this is much more than anticipated.

Thanks for the note. While we've been focusing on the D.C. region forecast, no doubt you should get some heavy snow around Newark.  A quick look at model output would suggest 5-10".

Do you think flights will be back to normal at DCA by tomorrow night?

I think so.

Do you have any update on the snow bands maps? In general, what are your thoughts for DC/Arlington timeline and accumulations.

Based on this morning's model output, we're leaning toward slightly higher accumulations.  We had said 3-6" around D.C. but now think 4-8" with some isolated higher totals.  It's hard to say exactly where the really heavy bands will set up...but models are pretty aggressive in simulating heavy snow rates in much of the region in that 4-8 p.m. windown.

Will temperatures keep the snow around or will we have a quick warm up?

No rapid warm-up.  30s Thursday and Friday.  Maybe some 40s over the weekend before more cold air next week.

I swear that at 6:30 this morning there must have been a frontal system hovering right at the Beltway interchange with Route 50. I went from driving in slush and sleet to suddenly it was just rain. Was there really as a dramatic change as it seemed?

With temperatures right around freezing, just a degree or two can make that kind of difference.  Our weather models actually simulated that quite well - showing the rain/snow line right around that area at 7 a.m.

I have theatre tickets tonight and plan to go no matter what. Usually I try to be out while the snow is falling and then hit the road after the road crews have had time to work. Do you think that'd an adequate strategy tonight, traveling from Penn Quarter to Bailey's Crossroads?

Depending on what time you're leaving to go to the theatre and where you're leaving from may be the issue.  I can't emphasize enough how bad it could potentially be between 4 and 8 p.m. tonight.  And snow could linger through 9 or 10 p.m. or a little later - so getting home may not be so easy.  A lot of your decision needs to be based on your driving experience, level of risk tolerance, type of vehicle, etc.

Hello Weather Gang! Could you offer a recommendation regarding rescheduling an early evening university class today? Right now nothing much is happening outside, so it seems hard to justify. Thanks!

We have pretty high confidence of moderate to potentially very heavy snow between about 4 and 8 p.m. tonight.

You recommend not being on the roads past 4 pm. How bad will the commute be just before then, in the 3-4 pm range? Also "dangerous" or still okay?

That's a tough one.  I suspect conditions will be going down hill then.  The precip may start as rain and may take a little bit to start sticking.  On the other hand, this whole system will move in rather in abruptly, and once the snow starts falling heavily, it will accumulate.  Bottom line- the earlier you can leave, probably the better.

I shared your forecast with my boss, now my office will close at 2. Thanks for the detailed and up to date report you provide.

Thanks.  I think your boss made a wise decision in this case.

Hi, The snow is projected to fall from 4pm-8pm in what areas? I am commuting south from the Baltimore area.

That 4-8 p.m. window includes Baltimore.

Being raised in New England, this wouldn't be a question but down here it's a different story. I have dinner reservations downtown followed by tickets to see a show at the Warner Theater tomorrow evening. Will things be back to normal for tomorrow's evening rush?

You should be ok.

Obviously, the weather will affect buses, but what about the subway? Any word from Metro on its plans for the evening commute?

I think I remember that metro operates fine except when snow exceeds 8" at above ground stations.  It's not out of the question some spots get that kind of accumulation so there could be some metro disruptions by later this evening.

I live in Arlington & have a doctor appointment scheduled for tomorrow near Sibley Hospital for 10:30 am. To cancel or not to cancel?

The snow probably ends before midnight giving crews time to clear the main roads.  Neighborhood roads will take longer... so it depends on where you live, what kind of vehicle you have, etc.

hi, im a HUGE fan of CWG, i was just wondering.. What do you think is the most likely accumulation at IAD? i know its a bad Q, and you don't really know, which is why you post ranges, but given that you're an expert, i assume you could at least say closer to 10, or closer to 5. I am hoping you could narrow it down to an inch, and i fully understand that this number is in no way definite, i was just curiose...

Thanks for reading our blog!  It's really tough to give an exact number - especially with this event where I think there may be a fair amount of variability due to localized heavy snow bands that set up.  But for the fun of it, I'll go with 7 inches.

I just noticed that the Winter Storm Warning extends until 4:00 a.m. Why so late since you expect the snow to end around midnight?

National Weather Service typically errs on the side of ending warnings later - to provide a little padding in light of the uncertainty about when it will end and to account for the large region covered by the warning.  Also, while I do think it will end around midnight, sometimes backlash snows can continue a little longer than modeled.  But it does look like the worst should be over by 9 or 10 p.m - with snow tapering after that.

So will we have school tomorrow?

With the exception of D.C. schools, I think there's a good chance of a snow day for most other systems. Not a guarantee though.

I have relatives who are scheduled to fly in to DCA this evening - due to land around 4:45 pm. Do you think they will be cancelling/diverting flights within that timeframe given the windows you've suggested for heaviest snowfall? As a follow on, why are some regional airports seemingly better equipped to handle snow? For example, I fly into Jackson Hole in snow all the time - whereas here flights appear to be cancelled. Is that due to relative lack of experience in dealing with snow (in Jackson vs. less snowy DC), or more reflective of our regional climes (more wet here than dry in Jackson), or more air traffic issues? Just curious how these kinds of decisions get made and why - fascinating stuff. Thanks Capital Weather Gang!!

I'm not really an expert of regional airport snow removal but it figures that airports that get a lot of snow would be most prepared to deal with it. 

A 4:45 p.m. arrival at DCA may be impacted by increasing snow and low visibilities.  I wish I could better predict what that may mean for their flight...but it's really hard to say.  It's possible that they're arriving sufficiently early that snow isn't really sticking yet.

You mentioned this morning the potential for thundersnow. Where/when could we see this?

It's not a sure thing- but that 4 to 8 p.m. window would be the most likely time.

What time should we be looking to leave work to avoid getting caught in the worst of the storm?

The earlier the better both to avoid the snow and the inevitable convergence on the roads between 2 and 4 p.m. due to the Fed gov early dismissal.

OK Jason. I'm looking outside and hearing about the 'gap' in the storms and wondering if I left by 2:00 to drive 70 miles north to Ski Liberty, could I make it up there without putting my family's life in jeopardy? And yes, I would plan to stay over (because I don't think that I would have any other option!).

You might be able to stay in front of the big thump if you leave soon.  But only go if you're comfortable driving in snow.  There was some accumulating snow in that region this morning.

How come we're not having any warm fronts? I think we've had like two days over 50 since December 1. Usually we get a few. Why the repetitive 30-35 highs for tow solid months?

It's been unusually cold due to a blocking pattern in the atmosphere related to unusually high pressure over Greenland - resulting in a cold current over Eastern North America.  The NY Times had a good article on it yesterday.

Flight from Dulles at 6 pm--do you think it will take off?? Thanks!!!

I think there will be delays and possible cancellations.

In the earlier forecasts, you guys put a lot of emphasis on the NW side of town seeing more snow. Is that still the case or are you expecting more uniform accumulations now?

Still think higher north and west because it's colder there and snow will stick better.  But not out of the question some areas in the immediate region or even east get as much depending on where heavy snow bands set up.

I moved to the area almost two years ago, and after last year's winter wonderland, I have to ask: do you think this will be our biggest snowfall of the season? I've been pretty disappointed so far this year, should I soak this in and enjoy it or do you suspect there will be more to come?? I know this can't be answered definitively, give me your gut feeling!

That's hard to say.  February is - on average - our snowiest month.  But if we get more than 6" from this - the odds of getting two 6" snowstorms in the same year are low.  Of course, last year we had 4 - which was highly unusual.

I've got to wrap up now to update the blog.  Really appreciate everyone logging in for this chat.  Stay safe this evening and avoid the roads if you can.  You can stay up to date with the latest storm info on the Capital Weather Gang blog .  You can also follow us on Facebook and Twitter (@capitalweather).

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Jason Samenow
Jason Samenow is chief meteorologist with the Capital Weather Gang.
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