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Posted at 10:30 AM ET, 01/26/2009

Storm Scenario: Some Snow, Then Ice and Rain

By Jason Samenow

* Cold, Snow and Slop: Full Forecast | Winter Storm Watch *

Next Chance of Accumulating Snow: Tues-Wed
Probability of Accumulating Snow: 80%
Most Likely Potential Impact:

A large, complex storm system will develop to our southwest later today which will throw multiple types of precipitation at us, starting tomorrow morning lasting into the day Wednesday.

I am fairly confident the precipitation will begin as snow tomorrow morning. The timing is a little less certain, but likely between pre-dawn and mid-morning (starting first in the west). Coverage may be patchy, with some areas getting snow, while other areas are dry. Intermittent, patchy light snow (with the possibility of moderate bursts) should continue well into the afternoon.

snowprob-jan27-28_09.jpg

Between late afternoon and mid-evening, the snow may start mixing with sleet -- especially along and south and east of I-95. Between mid-evening and midnight, mixing should start occurring everywhere, with sleet and freezing rain gradually becoming the dominant precipitation type.

Before the changeover, I'd say 1" of snow is most likely in the District and points south and east, with 1-3" north and west of town. Other possibilities are shown in the chart on the right (if you live north and west of the beltway, add an inch or so to the various snow possibilities).

Keep reading for more on this winter storm scenario...

After the snow ends, some accumulation of ice is possible, with significant icing not out of the question in the north and west suburbs. However, in most of the area, it does look like the ice will have a good chance of changing to plain rain by early Wednesday morning -- reducing the likelihood of a horrendous a.m. commute (Wed.). Having said that, we'll need to carefully watch temperatures.

Rain showers are likely during the day Wednesday, but it's not out of the question they briefly change back to snow before ending (little or no accumulation foreseen).

The Snow Lover's Crystal Ball appears when the potential exists for accumulating snow beyond 24 to 36 hours.

By Jason Samenow  | January 26, 2009; 10:30 AM ET
Categories:  Snow Lover's Crystal Ball  
Save & Share:  Send E-mail   Facebook   Twitter   Digg   Yahoo Buzz   Del.icio.us   StumbleUpon   Technorati   Google Buzz   Previous: Forecast: Cold, Snow, and Slop
Next: PM Update: Tues-Wed Storm Still on Track

Comments

What are the chances that temperatures will not rise above freezing north and west at all? Actual temperatures seem to be lower than forecasts in recent weeks in areas like upper Montgomery County.

Posted by: uncledak | January 26, 2009 10:41 AM | Report abuse

Do you think conditions will be poor enough by 6am tomorrow morning for schools to be closed? Nothing angers me more than going into school, only to have the announcement that they are releasing early. It makes for a missable drive home (270N from silver spring to germantown)

Posted by: PoorTeacher | January 26, 2009 10:54 AM | Report abuse

Clouds with fangs wow thanks for the heads up! Since the Nosferatu will be out on Wed I won't be :-)

Posted by: curandera333 | January 26, 2009 10:55 AM | Report abuse

Clouds with fangs... hah.

Posted by: PoorTeacher | January 26, 2009 11:11 AM | Report abuse

It just HAS to get warmer as the night goes on. That's just great.

Hey PoorTeacher, if we go to school and then get dismissed early...does that day count as one of the 180 required days of school? Maybe it's a cheap way out for school systems to not use up a snow day....?

Posted by: PeterBethesda | January 26, 2009 11:17 AM | Report abuse

its quite depressing. yesterday everyone was like "its going to be cold and alot of snow" but now its rain. why do the modles do this to us?!?!

Posted by: samdman95 | January 26, 2009 11:27 AM | Report abuse

An emergency early release counts as a day of school. It is a good way to avoid using a contingency day, unfortunately.

Posted by: anon34 | January 26, 2009 11:28 AM | Report abuse

samdman95 -- Frustrating, I know ... but that's the nature of models. That's why as meteorologists we have to restrain ourselves from changing our forecasts too much based on just one or two model runs.

Posted by: stillmand | January 26, 2009 11:40 AM | Report abuse

is there any chance the models are wrong and we will get 4+ inches of snow. Also is a schoolcast for tuesday and wednesday coming out soon?

Posted by: samdman95 | January 26, 2009 11:44 AM | Report abuse

One good snowstorm. Just one. Evidently it's too much to ask this winter, or for the past six.

Posted by: hobbes9 | January 26, 2009 11:44 AM | Report abuse

agree with all it is disappointing situation. The 12z GFS does show 4" on snow on the ground in DC assuming 10:1 ratio, but I don't necessarily trust the model outputs, especially given the placement of the 540 line and the 850 temps. Sometimes the model outputs do not compute.

Posted by: mciaram1 | January 26, 2009 11:59 AM | Report abuse

I know I am an adult, but I am tempted to wear the PJs inside out just because I am so desperate for snow....

Posted by: ksrgatorfn1 | January 26, 2009 12:09 PM | Report abuse

ksrgatorfn1,

Don't forget to flush ice cubes down the toilet, too!

Posted by: kjhealey | January 26, 2009 12:15 PM | Report abuse

Do we expect surface temps to get above freezing in the close in suburbs of DC on Tuesday/Wednesday? If so, when?

Posted by: snowlover | January 26, 2009 12:43 PM | Report abuse

I think I've asked this question before, but I can't remember the answer...

When a forecast talks about points "north and west" and "south and east," what does that mean?

Visualizing a compass centered on DC, points "north" are anywhere from 270 degrees to 90 degress on the compass. Points "west" are points from 180 degrees to 360 degrees. Does "points north and west" mean points that are both north AND west (270 degrees to 360 degrees), or points that or north OR west (180 degrees to 90 degrees)? Or does it divide the compass evenly between "north and west" (225 degrees to 45 degrees) and "south and east" (45 degress to 225 degrees), with no other possibilities?

Yes, I'm anal.

Posted by: litigator02 | January 26, 2009 12:51 PM | Report abuse

Please please please let it snow or ice, just do it in time to cancel school either tomorrow or Wednesday!!

Posted by: debbie_in_rockville | January 26, 2009 1:14 PM | Report abuse

I'm pretty sure it means, by your definition, points north OR west, otherwise they would just say points northwest. It means places like Loudoun as well as Montgomery. At least that's my understanding.

Posted by: amorris525 | January 26, 2009 1:15 PM | Report abuse

I think Snowy Hill and Buster Dryground should dub this "Typical DC Winter Storm '09." We usually get several of these snow to ice to rain events - this year is only odd in the fact that we may only get one of them, not in the fact that we haven't gotten a major snowstorm. But the pattern - maybe an inch, then ice, then rain - is very typical for DC.

If you want snow, go up to Northern New England. I was there for over a week earlier this month and they have more snow on the ground there than I have seen in years. And relatives told me they lost a lot of what they got during the warm spell at the end of December.

Posted by: SouthsideFFX | January 26, 2009 1:23 PM | Report abuse

Here's an idea, relevant as spring approaches: In addition to the Snow Lover's Crystal Ball and the Fair Weather Sun, why not roll out a "Severe Weather Thunderbolt" for those folks who look forward to our more exciting weather during the warm season??? [It could also be used during hurricane season when severe tropical weather threatens!]

Posted by: Bombo47jea | January 26, 2009 1:27 PM | Report abuse

I am 31 years old and a resident of Rockville, MD. As a kid I spent my winters hoping for even a trace amount of snow (knowing this would be enough to cancel school). As an adult, I dislike these borderline storms which produce just enough to make my commute to work a nightmare but not even to cancel the government (for which I am a contractor to). It sucks growing up.

Posted by: authorofpoetry | January 26, 2009 1:27 PM | Report abuse

@amorris525

You got it -- N & W would include both Montgomery and Loudoun

Posted by: CapitalWeatherGang | January 26, 2009 1:27 PM | Report abuse

I know Fairfax County School will be out for students tomorrow -- and not because of the weather -- Teachers work days Mon and Tues this week. Maybe we will get enough snow that teachers will get to miss too.

Posted by: photojenn | January 26, 2009 1:34 PM | Report abuse

Here is my weather blog for our area:

Winter - .02% chance of accumulating snow. Temperatures cold when no storm systems pass...warming up to 33 degrees when they do.

Spring - That's funny. We don't really have spring.

Summer - Hot and humid with a 50% chance of thunderstorms. Humidity will be so oppressive that anyone driving without air condition will go insane.

Fall - That's funny. We don't really have fall.

Welcome to the D.C. metro area. Enjoy your stay!

Posted by: authorofpoetry | January 26, 2009 1:55 PM | Report abuse

More on "north and west"...

Would it include Dale City? (West, but definitely not north)

What about Annapolis? (North, but definitely not west)

Posted by: litigator02 | January 26, 2009 2:16 PM | Report abuse

Here is the rule of thumb

North or West of the beltway.

Inside the beltway its too warm. You only get something when there is a major event.

Also I-95 is usually a good indicator of snow vs ice or ice vs rain with the snow or ice usually on the left (West) and the ice or rain on the right (east) respectivelly.

Posted by: novamiddleman | January 26, 2009 2:32 PM | Report abuse

So I'm assuming that if there was to be a schoolcast that it wouldn't be up now anyway because we don't quite know what the storm will bring?

Posted by: strangldangel | January 26, 2009 3:09 PM | Report abuse

litigator02:

No, it wouldn't. I would think of northwest/north and west/north or west as this way.

Imagine an area west of I-95 and I-83 in Maryland; North of I-66 in Virginia; and outside (westward) of the capital beltway (I-495) and Baltimore beltway (I-695).


Please see the map here
http://www.aaccessmaps.com/images/maps/us/dc/virginia_northmaryl/virginia_northmaryl.gif

Posted by: jpl1019 | January 26, 2009 3:10 PM | Report abuse

Count me in as a doubter, due to the ever-northward push of the 540 line. Hope I'm wrong.

Posted by: curtmccormick | January 26, 2009 3:12 PM | Report abuse

Thanks for including the probability distribution for different accumulations! It's exactly the sort of clear information (including clear information about uncertainty and risk) I wish was standard on weather reports.

Posted by: jwind | January 26, 2009 3:17 PM | Report abuse

jwind--if you want clearer info on uncertainty and risk, if you're not already doing so, check out the discussion that the NWS issues with its products. If you use the NWS site, it's the Discussion link under Forecasts on the left banner. If you use the Weather Underground, it's the "scientific discussion" that appears after the textual forecast. wunderground.com also fleshes out all of the abbreviations (or tries to) that the meteorologists use.

Posted by: jkuchen | January 26, 2009 3:23 PM | Report abuse

Not sure if it's my browser acting up again, but it looks like no one has commented on this yet, so here goes:

The latest products came out about 20 minutes ago, and we've got a winter weather advisory going into effect before the winter storm watch now. Maybe up to a half-foot between the two systems (at least in Centreville).

Posted by: jkuchen | January 26, 2009 3:26 PM | Report abuse

boy, you guys had me psyched for snow. btw, what happend to friday's storm?

Posted by: walter-in-fallschurch | January 26, 2009 3:32 PM | Report abuse

There's no strict definition to North and West. Generally I take it to include the following in the immediate metro area:

Montgomery County, MD
Fairfax County, VA
Western part of Prince William County, VA
Loudoun County, VA

And obviously, within these, the MORE north and the MORE west you go, the better. For example, Tyson's Corner and Burke, generally, get a bit more than downtown DC, but less than Centreville and Leesburg.

Posted by: jahutch | January 26, 2009 3:50 PM | Report abuse

I will believe it when I see it. I have been lied to once too many times. To all you youngins, once upon a time during winter, one foot plus of snow was a regular occurrence.

Posted by: RickJohnson621 | January 26, 2009 4:08 PM | Report abuse

Amorris525 maybe you should invest in a cheap compass.

Posted by: MKadyman | January 26, 2009 4:23 PM | Report abuse

how do you get south of I-95? isn't that somewhere in florida?

Posted by: slickwil2000 | January 26, 2009 4:45 PM | Report abuse

One foot plus of snow in one storm was never a regular occurence in this area!!! Maybe once every several years, but not a "regular occurence." Spreading such misinformation feeds into other false statements about the impact of climate change, etc.

Posted by: SouthsideFFX | January 26, 2009 5:00 PM | Report abuse

SouthsideFFX wrote:
One foot plus of snow in one storm was never a regular occurence in this area!!! Maybe once every several years, but not a "regular occurence." Spreading such misinformation feeds into other false statements about the impact of climate change, etc.


-----

Oh you are so young. I am talking of the 80s. Talk to Mayor Barry, he will tell you. That is an inside joke those around the 80s will get.

Posted by: RickJohnson621 | January 26, 2009 5:21 PM | Report abuse

Don't let the facts get in the way of your opinions:

Total number of days with 12"+ of snow, Jan. 1 1980 through Dec. 31 1989: ONE (out of 3653 days)

Here are all 7 of the days in the 1980s with more than 6" of snow:

1/8/1988	6.3
1/13/1982 6.4
12/12/1982 6.6
2/23/1987 6.9
1/22/1987 10.8
11/11/1987 11.5
2/11/1983 16.4

Posted by: CapitalClimate | January 26, 2009 5:56 PM | Report abuse

Oh lord I have run into weather Nazis. The only point I was trying to make was back in the day you could count on seeing snow and lots of it in the winter. Okay, maybe not one foot plus. It just seem like that to me. Seriously, some of you folks need to get a life. No need crying about this. I don't care either way.

Posted by: RickJohnson621 | January 26, 2009 6:23 PM | Report abuse

Finally figured out what the issue is. All these liberal democrats are moving in from New England and other Northern areas. They remember their childhood and don't realize that DC barely EVER gets any snow.

Posted by: novamiddleman | January 27, 2009 10:26 AM | Report abuse

The comments to this entry are closed.

 
 
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