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Posted at 12:30 PM ET, 01/20/2011

Tonight's snow to be very light, again

By Capital Weather Gang

Snow may mix with rain DC south

Some winters tend to take on a certain character. Last winter, as we all remember, was the winter of the big storm (after storm, after storm). This winter, at least so far, appears to the winter of the little storm. That's not to say that we can't or won't get a big one at some point, but it's almost certainly not going to be tonight's, which is probably too weak and tracking too far north to produce more than half-inch or so in D.C. and to the south, with maybe a little more north, especially areas under a Winter Weather Advisory north of Montgomery County.

FORECAST SUMMARY

The bulk of the metro area is likely to get nothing more than a trace to around a half-inch, with up to about 1" possible for northern sections (central/northern Loudoun, central/northern Montgomery, and Howard counties). Timing of the main area of precipitation looks to be between 8-10 p.m. (west) and 4 a.m. (east) tonight. See later in this post for an accumulation map by zone.

IMPACT FORECASTS

StormCast

TravelCast

SchoolCast (for Fri., Loudoun, Frederick & Howard Co.)

SchoolCast (for Fri., everywhere else)

FedCast (for Wed.) capitol-black.jpgcapitol-black.jpgcapitol-gray.jpgcapitol-gray.jpg

STORM FAQ

Where is the precipitation now?

Follow the progress of the storm on national radar, regional radar and satellite.

How confident are you in your forecast?

Confidence is fairly low since the D.C. area looks to be toward the southern or southwestern edge of accumulating snow. That means if the storm shifts even slightly north or northeast, we could be left with no accumulation at all. Being "dry slotted" with little to no snow is often a concern with storms like this, where low pressure is expected to develop off the coast to our east and strengthen only once it's heading away from us to the northeast. Also, especially from the District and to the south and southeast, temperatures may be too warm for snow to stick much and rain may even fall at times.

Keep reading for more FAQs and "storm" effects by zone...

Who will get the most/least amount of snow?

This one's easy. The most snow will almost certainly fall north of town, with the possibility of little or no accumulation from the District south. Here's a breakdown:

jan21-2011.jpg
Zone map with accumulation potential.

Zone 4: Generally around an inch is possible from Frederick and Baltimore and points north. The city of Baltimore may struggle to get an inch due to lack of sticking and temperatures near or slightly above freezing. A few spots with elevation north of Baltimore and Frederick could get 2".

Zone 3: The ceiling for accumulation in D.C.'s northern suburbs is around 1". Spots which have the best chance of an inch include the high spots in Montgomery county and northern Loudoun county.

Zone 2: Because temperatures are so marginal for this event - at or possibly above freezing - and as precipitation will likely be light, we think it's going to be hard to get much more than a coating to half an inch in this zone - which includes most of the immediate metro area. This zone may even see some rain.

Zone 1: You definitely don't want to be here if you're a snow lover. This zone is on the south end of the precipitation shield and may deal with rain at times. A dusting to a coating may be the best you can do.

What does Wes Junker, CWG's winter weather expert, think about this storm?:

Wes tells us:

I'd be surprised if anyone in the DC area ended up with an inch of snow. The surface temperatures now forecast by the models to be above freezing through 4 a.m. even around Baltimore. The temperatures certainly introduce the possibility of a mix or even rain at times when the precipitation rates are low. My guess is for a dusting to maybe a half inch except possibly a little more over the highlands north of Baltimore.

What are the chances of lower or higher amounts of snow than forecast?

If the storm turns out stronger and develops and strengthens further south than expected, then we could be looking at as much as 1-2" (10-20% chance), but the potential for anything much more than that is pretty low. If anything, the risk is probably greater that we "bust" on the low side with no accumulation (25% chance) and even rain, for the reasons discussed in the forecast confidence FAQ above. This is especially true for areas south of D.C.

Will the snow stick?

Eventually it may, but probably not right at the start, especially downtown where temperatures may be right at or a little above freezing. If the snow is heavy enough, it may allow for some modest accumulation, especially north and northwest of the District.

What about schools?

If accumulations reach the half-inch to 2" range, then there's a chance of some delays tomorrow morning. Closings seem unlikely. Though if there were to be any, they'd likely be to the north toward Frederick and Baltimore, where the highest snow amounts are expected.

What will conditions be like in other I-95 cities?

Once again, cities northeast of D.C. will see more significant snow ranging from 2-3" around Philadelphia to 3-5" or so in New York City and Boston.

Why so may little storms but no big storms this winter?

It's all about the prevailing storm track and pattern this year, which has primarily had storms developing off the mid-Atlantic coast and then strengthening as they move away from us to the northeast. That favors more snow for places like Philadelphia, New York and Boston, and less snow here. Last year, El Nino conditions (warmer-than-average sea surface) in the equatorial Pacific Ocean helped to energize the southern branch of the jet stream, allowing storms to form further south with time to intensify on their way north before reaching the D.C. area. This winter, a La Nina (cooler-than-average sea surface in the equatorial Pacific) has led to a less active southern branch of the jet stream and storms that form and intensify further north (influenced more so by a more dominant northern branch of the jet stream).

By Capital Weather Gang  | January 20, 2011; 12:30 PM ET
Categories:  Forecasts, Latest, Winter Storms  
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Next: PM Update: Awaiting tonight's light snow

Comments

Do you guys think the Advisory north of the district will end up being canceled?

Posted by: Dylan0513 | January 20, 2011 12:48 PM | Report abuse

fyi tomorrow is a scheduled half-day for Howard County schools so what would normally end up in a 2-hr delay will likely result in a closing...

Posted by: Efren3 | January 20, 2011 12:51 PM | Report abuse

So, now that this is a likely bust... what's next week looking like? ;-)

Posted by: wappledoo | January 20, 2011 12:54 PM | Report abuse

"A dusting to a coating may be the best you can do."

So is this like .01 inch to .02 inch? I thought a dusting and coating were the same thing.

Posted by: Showmethesnow | January 20, 2011 1:12 PM | Report abuse

Tomorrow is also a half day for Fauquier County (exams).

Posted by: jms8 | January 20, 2011 1:13 PM | Report abuse

These weather reports throughout the week are becoming more like "the boy who cried wolf." Earlier in the week - "We may be looking at something a little more significant," to - "we may get dry slotted." I know we can't control weather but some weather blogs, mets, etc. need to control their excitement and look at the trends. This may be our winter of dustings to a few inches.

Posted by: greg2010 | January 20, 2011 1:23 PM | Report abuse

@greg2010

Thanks for the comment. Here at CWG we haven't gotten very excited about this one at all, pretty much calling from the beginning for as little as a dusting or half-inch to as much as 3" in the snowiest scenario.

Posted by: CapitalWeatherGang | January 20, 2011 1:26 PM | Report abuse

Same trend as always....calling for 1-3...then we may get dry slotted or a dusting...will we ever get a storm this year where the total goes up and stays up till the end?

Posted by: BradFinWoodbridgeVA | January 20, 2011 1:35 PM | Report abuse

i love hearing when the uncertainty in the forecast could me even less than a trace to half inch! I would love to see nothing or maybe at most some flurries or especially just plain ol rain here in hyattsville!

Posted by: KRUZ | January 20, 2011 1:35 PM | Report abuse

@greg2010

On the contrary, people were criticizing us for downplaying this on Tuesday because they saw the models showing more and wondered why we were predicting so little. We knew the setup looked bad, and only gave 30% odds of an inch. We've been consistent in NOT liking the potential for much snow from this one despite the models and other more "bullish" forecasts.

Posted by: Jason-CapitalWeatherGang | January 20, 2011 1:38 PM | Report abuse

@BradFinWoodbridgeVA

We never called for 1-3"... we said a dusting to 2" yesterday - which is effectively what we're saying today, but tilted toward the low end.

Posted by: Jason-CapitalWeatherGang | January 20, 2011 1:40 PM | Report abuse

If La Nina is going to dominate, can I at least get the NAO to stay positive? I'm tired of this COLD dry pattern. It is supposed to be WARM and dry! Oh well, maybe Tuesday's storm will produce, but looking like out to sea at this point.

Posted by: jb41477 | January 20, 2011 1:41 PM | Report abuse

And let the games begin! Snow lovers, upset about getting less snow than they want, attack CWG!!!

Posted by: SouthsideFFX | January 20, 2011 1:48 PM | Report abuse

@jb41477

There is hope for Tuesday's storm, and it just got a little brighter via the 12z Euro.

Posted by: bbirnbau | January 20, 2011 1:48 PM | Report abuse

really hoping tuesdays storm goes out to sea because all the wx bloggers are really hyping next weeks late week storm on the gfs :/

im hoping IF that one hits, its rain!!!!

Posted by: KRUZ | January 20, 2011 1:50 PM | Report abuse

greg,
at this point, i'd be THRILLED with "a few inches". it's really not too much to ask....

all,
these dustings to coatings (i'd say a dusting is less than a coating) have been so discouraging. along those lines, i began been wondering just how "out of whack" our expectations are after last year. well, according to

http://www.erh.noaa.gov/lwx/winter/storm-pr.htm

every year washington dc (DCA) can expect:

(5)1" storms
(3)2" storms
(1)4" storm
(.6)6" storms (3 in 5 yrs)
(.3)8" storms (3 in 10 yrs)
(.2)10" storms (1 in 5 yrs)
(.12)12" storms (1 in 8 yrs)

these totals must be inclusive - meaning the 4" storm "counts" as one of the 2" and 1" storms. the totals, of course, are higher for dulles... this site didn't mention how many dustings-to-coatings-to-1" storms we usually get.

anyway, these numbers show it is not unreasonable to expect a 4" storm every year. and we "should" get a 6" storm more than every other year. dulles gets a 6" storm practically every year - (9 of 10 years).

i don't know what the official totals are for this year, but i only recall ONE storm so far of over an inch. not a good year for snowlovers. DUH...

Posted by: walter-in-fallschurch | January 20, 2011 1:55 PM | Report abuse

As a snow hater I love La Nina! Let's get rid of that negative NAO though.

Posted by: rwalker66 | January 20, 2011 1:59 PM | Report abuse

CWG

i was talking about the trend for the whole season so far seemed to be higher amounts ..then dropped off..almost everystorm has seemed to do that..IMHO.I wasnt talking about just this storm and its always you guys..itsthe TV broadcast that are really bad about it IMHO.

Posted by: BradFinWoodbridgeVA | January 20, 2011 2:01 PM | Report abuse

What is the chance of icing on Friday morning?

Posted by: heatherdc1980 | January 20, 2011 2:03 PM | Report abuse

Not sure how much control you guys have over this, but the lead headline of the metro section reads "Get ready for a snowy mess in the morning", but when you click on the link and get to the capital weather gang page you see "Tonight's snow to be very light". I believe that the metro section headline is misleading and would lead one to believe that we are in for a several inch event, which I am assuming now is not the case? Just seems like the metro section headline would create unnecessary worry if indeed we are only receiving a dusting in metro area.

Posted by: Axel2 | January 20, 2011 2:03 PM | Report abuse

@walterinfallschurch

thanks for posting those numbers! with that info it is of my opinion that we shouldnt get not even 1 more inch the rest of this winter.... We received 3 winters worth of snow last winter, lets have a couple of 6 inch (total) an under winters for the next couple of years!!!!!

Posted by: KRUZ | January 20, 2011 2:05 PM | Report abuse

I've been bearish about tonight's snow event and agree with the CWG forecast.

One matter of concern, however, is a band of moderate to heavy snow that has formed from Cincinnati to Louisville and back to Arkansas. If that band can hold together, us snow lovers might get a pleasant surprise.

Posted by: frontieradjust | January 20, 2011 2:05 PM | Report abuse

What is the chance of icing on Friday morning?

Posted by: heatherdc1980 | January 20, 2011 2:06 PM | Report abuse

Us snow haters have been thrilled with this winter to date. Keep those dusting s coming.
And ytd you guys have been right on the money for each of these events. Keep it up.

Posted by: bdarby123 | January 20, 2011 2:07 PM | Report abuse


Ok, so we're NOT going to bring the tractor out with the plow like we did for the other small "events"...It's looking like we in Hamilton VA will get a dusting to 1". Right? (Will not bringing it out bring us luck?) Wishful thinking.

Posted by: worldtraveler83 | January 20, 2011 2:11 PM | Report abuse

KRUZ,
hahaha. the problem with your thinking is that nature doesn't remember last winter.

just like if you flip a coin and it comes up heads 5 times in a row, on the next flip, you still have a 50% chance of heads...(assuming the 5 times in a row wasn't a product of a "loaded" coin...).

Posted by: walter-in-fallschurch | January 20, 2011 2:13 PM | Report abuse

KRUZ,
see, i look at those numbers and say we're "due" 4 more 1"+ events - one of which "should" be a 4" or possibly a 6" event...

Posted by: walter-in-fallschurch | January 20, 2011 2:16 PM | Report abuse

@ walter-in-fallschurch

You are correctly describing the inverted "Gambler's Fallacy", but I thought climatetology was somewhat based in patterns, trends, etc...which would be different from the complete neutrality of a coin flip. Meaning I think we should be able to make an educated guess of what will happen "tomorrow" in weather, based on what happened "yesterday" or a collection of "yesterdays"...right? We can't do that with a coin flip (ergo the gambler's fallacy)

Posted by: kwojciec | January 20, 2011 2:23 PM | Report abuse

CWG,

Can you give meteorological definitions for a dusting, a coating, and a trace? What is the heirarchy here?

Posted by: Showmethesnow | January 20, 2011 2:31 PM | Report abuse

kwojciec,
yeah, i suppose you're right about weather patterns and all. i once had a client who worked for the navy. he described a study they did for predicting the weather. they compared several studies including several complex models and all that, but the most reliable prediction for tomorrow's weather was "same as today"...

also, what i said about a "loaded" coin might be analogous to things like ENSO and NAO and other seasonal factors. it appears this winter is "loaded" so as not to produce storms for dc... (philly, ny, boston, and even SOUTH CAROLINA (!?!?) not so much).

Posted by: walter-in-fallschurch | January 20, 2011 2:34 PM | Report abuse

@Showmethesnow

A trace indicates that some snow occurred, but it was below the detectable limit.

A dusting is a covering on the ground.

A coating is a little more than a dusting - a thick dusting.

Posted by: Jason-CapitalWeatherGang | January 20, 2011 2:37 PM | Report abuse

Thanks for the clarification.

Posted by: Showmethesnow | January 20, 2011 2:38 PM | Report abuse

Both the Euro and the GFS show something brewing next week. The Euro has a Low off of the NJ Coast on Wed... while the GFS has a pretty moisture laden system hanging around the gulf during the same time period. I know that it is useless to look at the exact location of Surface Lows and QPF this far out. My question then would be... are there any model features that have shown more confidence in the long range, other than the surface lows/ QPF, that could give us clues about the overall pattern/ set up for next week?

Posted by: jac8949 | January 20, 2011 3:01 PM | Report abuse

Man the brooms!!!!!!!!

Posted by: moo1 | January 20, 2011 3:16 PM | Report abuse

greg2010 - I don't remember any forecaster, ESPECIALLY on this site, EVER hyping this storm...except maybe some people adding comments about how they thought it would hit 3"+ (the people who follow accuweather b/c they don't like to accept reality). Not sure where that came from...maybe it was hyped in your mind? The worst I read or heard was 1"-3" which is basically a non-event.

Posted by: parksndc | January 20, 2011 3:17 PM | Report abuse

@jac8949

One thing I like about the setup (for snow) is the high to the north which should help lock in cold air at least early on (it may slide away though) in the storm and may help generate temperature contrast to feed a developing low off the coast (technical term: frontogenesis). Wes will do an analysis tomorrow

Posted by: Jason-CapitalWeatherGang | January 20, 2011 3:23 PM | Report abuse

Sorry, snow-lovers. This is all my fault for listening to my wife, and buying a snow thrower earlier this season. My humble apologies...(on behalf of my wife, that is)

Posted by: DoubledownDC | January 20, 2011 3:28 PM | Report abuse

I don't like that southerly wind at DCA and points east, maybe just a fluke ob, but Andrews, DCA, and BWI are in the 40's with a southerly component(vrb @ BWI), and IAD is still at 39 with a northerly wind.

Posted by: Brian-CapitalWeatherGang | January 20, 2011 3:31 PM | Report abuse

@Jason,

I would say this Tuesday looks like our best shot for sig snow this year besides that misnomer from Boxing Day. Although it may change to rain for a period, it seems that the chances for significant precipitation are pretty good for this far out. Would I be correct in this assumption? Maybe a ten percent chance for sig snow at this point? Not bad for over four days out.

Posted by: bbirnbau | January 20, 2011 3:46 PM | Report abuse

Temperatures have way overperformed today - 44 at DCA vice mid-30s forecast, and it seems that there was a lot more sunshine (albeit filtered through high clouds) than was forecast. Since temperatures are starting higher, does this mean less likelihood for snow? Although, the Weather Channel computer generated forecast now says 1-2 inches instead of the 1 inch they said earlier in the day. But, they never have the temperature going below 35 until the snow is over and the cold air starts blowing in as the winds pick up. Doesn't make sense, but that is a machine-generated forecast.

Posted by: alrob8 | January 20, 2011 3:52 PM | Report abuse

Humph. Some guy on the radio said 1-3 inches on my way home this afternoon and I got excited. *siiiiigh*

Posted by: megamuphen | January 20, 2011 3:53 PM | Report abuse

Why do people love snow so much? Weird...

Posted by: fakedude2 | January 20, 2011 3:55 PM | Report abuse

If it's too warm, any ice or wintry mix possible?

Posted by: bastings | January 20, 2011 3:57 PM | Report abuse

@alrob8

The relatively warm temps (yes, higher than we forecast) are one of the reasons we're predicting modest snow totals.

Posted by: Jason-CapitalWeatherGang | January 20, 2011 3:57 PM | Report abuse

why did cwg write a huge article with a zone map when the most we will get is .5 inches of snow?

DC makes such a big deal about snow and weather. its really annoying. we are all babies that freak out when we get an inch of snow. MAN UP DC!

Posted by: SNOWLUVER | January 20, 2011 4:02 PM | Report abuse

@SNOWLUVER

You're right. It is a lot of coverage for a small event, but people asked for a zone map and we delivered :) Plus, doing this is our job and there wasn't a lot of other big weather news today.

Also, while, we're saying 0.5" is most likely, there's an outside chance of an 1" or so, as we state in the FAQ above.

Posted by: Jason-CapitalWeatherGang | January 20, 2011 4:08 PM | Report abuse

@SNOWLUVER

By commenting on this blog you are answering your own question ;)

Posted by: bbirnbau | January 20, 2011 4:14 PM | Report abuse

Hey well it is DC and its view of snow that keeps CWG in business ;)

Posted by: Camden-CapitalWeatherGang | January 20, 2011 4:47 PM | Report abuse

hopefully in a very lucrative (for our beloved mets) business!!

Posted by: kolya02 | January 20, 2011 4:54 PM | Report abuse

@Jason-CapitalWeatherGang thanks for the feedback. I really appreciate it. Regarding next weeks storm, I was reading on some WX forums where they were talking about a situation where the strong high to the north and a week surface low to the south combine to create lift and steady precip. They also mentioned a strong baroclinic zone … similar to PDII. Is there an validity to this in the model runs?

Posted by: jac8949 | January 20, 2011 5:00 PM | Report abuse

@jac8949

I think PDII is a big stretch... but there is a nice baroclinic zone. The tricky part of this the timing/intensity/placement of the upper level features.

Posted by: Jason-CapitalWeatherGang | January 20, 2011 6:20 PM | Report abuse

CWG, I really like the zone maps you've been using for this and the last snow event. I am also very happy to be in Zone 1 this time!

Posted by: david_in_stafford | January 20, 2011 6:43 PM | Report abuse

Howard County's got a halfday tomorrow, so I doubt that we'll have school even if we've got an inch or two (it's annoying since I have exams tomorrow).

Good job covering this one CWG! :)

Posted by: DelMarVaStormTracker | January 20, 2011 6:44 PM | Report abuse

*i posted this on the other thread also* the new map last time showed my area here in madison va, i thought?? is there a way to get a larger overall look at the map, say like 75 mile radius of wash dc.

Posted by: deveinmadisonva | January 20, 2011 6:45 PM | Report abuse

The comments to this entry are closed.

 
 
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