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Posted at 7:20 PM ET, 01/ 7/2011

Winter weather advisory N and E of D.C.

By Ian Livingston

Dusting to 1" possible; more Tuesday?

7:20 update: The National Weather Service has issued a winter weather advisory from 1 a.m. until 1 p.m. Saturday to the north and east (map) of D.C. The advisory in this area calls for up to 1-3" of snow.

3:30 p.m. Clouds held pretty tough today and that's helped keep temperatures from rising too far. Highs mainly in the low-and-mid 30s mixed with an occasionally gusty wind from the northwest have also kept wind chills in the 20s. We saw a little snow shower activity early morning and some more in the way of snow potential is around the corner tonight and into tomorrow.


Radar & lightning: Latest regional radar shows movement of precipitation and lightning strikes over past two hours. Refresh page to update. Click here or on image to enlarge. Or see radar bigger on our Weather Wall.

Through Tonight: There could be a few flurries around early, but the risk for snow shower activity grows by midnight with the best odds afterwards and toward dawn. This activity could be hit-or-miss, but where it happens there is a good shot at some accumulation. Lows reach the low-and-mid 20s in the suburbs to the upper 20s downtown.

Tomorrow (Saturday): The risk of snow showers continues into the midday (late morning west, early afternoon east) before sun starts to break through. Accumulation should generally be minor, or about a dusting to 1" with more possible in isolated spots and mainly northeast of here. Temperatures probably don't top freezing in some locations, with a range between 30 and 35 pretty likely. Winds that are light early pick up quite a bit by afternoon and evening. It's going to be cold!

See Camden Walker's forecast through the weekend. And if you haven't already, join us on Facebook and follow us on Twitter.

Sky smile: Winter got you down? Check out this neat atmospheric phenomenon. Two rainbow-colored arcs in the sky met up over Baltimore recently, and Frank Roylance of the Sun explains how it came together.

By Ian Livingston  | January 7, 2011; 7:20 PM ET
Categories:  Forecasts  
Save & Share:  Send E-mail   Facebook   Twitter   Digg   Yahoo Buzz   Del.icio.us   StumbleUpon   Technorati   Google Buzz   Previous: Tuesday snow risk increases
Next: Forecast: Snow ends. More Tuesday?

Comments

There's that four letter word I've come to detest: WIND.

Posted by: FIREDRAGON47 | January 7, 2011 3:53 PM | Report abuse

Has anyone else seen the GFS at 300 hours?

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/12/images/gfs_p48_300s.gif

WAAAAY too early to get excited, but it could give us 5 - 10 inches!

Posted by: BobMiller2 | January 7, 2011 4:00 PM | Report abuse

then why are you getting excited?

Posted by: bbirnbau | January 7, 2011 4:09 PM | Report abuse

I have a question:

How come this afternoon it seems that the mets are starting to lean towards a storm developing for Tuesday? The models are still taking it off the coast, but some of the mets are pretty sure that the models aren't seeing the phasing with the plains feature like they should.

Can any of the gang explain the sudden boost in potential snow for Tuesday?

Posted by: bbirnbau | January 7, 2011 4:21 PM | Report abuse

On the previous post, Wes has an image that says "simulated radar for 7 am Saturday". Can someone post a link to a site that has this so-called simulated radar??

THANK YOU!!

Posted by: BobMiller2 | January 7, 2011 4:28 PM | Report abuse

bbirnbau - I have noticed an uptick in probability of precip as well but it's well in line with Wes' 40-50% which he already explained.

Posted by: parksndc | January 7, 2011 4:28 PM | Report abuse

Parksndc, yeah you're completely right I did not see Wes' post from earlier today because I got too excited about the new post. I just read over it. Gotta say I'm still feeling greedy. Although it smells of a 1-3 incher, which is almost worse than no snow in my book, I'm feeling lucky with the trending. Hopefully we can get this thing going on an outlier to the west.

Posted by: bbirnbau | January 7, 2011 4:31 PM | Report abuse

bbirnbau -
I personally think its rather misleading to keep stringing people along about a costal storm as, for instance, TV mets have been doing ALL week. Especially since this winter season has seen a few weather systems fail to develop or go south and OTS already.
There is a lot of disagreement amongst the models, and to me it looks the the best and most commonly used ones are doing the same things they did several times already this winter.

Someone on here asked the question "which numerical model is best?" I laughed out loud at that one...Apparently it did not occur to someone that if one model were "best" then nobody would feel the need to have additional models or scrutinize their differences.
The key to modeling is that you're faking reality...so you're making concessions. I don't know squat about weather model design, but can say that anytime you make a "model" in anything, it can optimize on different aspects of the environment being worked with. Oh and its only as good as your starting data. So thrown in chaos theory. I guess they try to crack that problem with the ensembles.

Posted by: AndrewRockville | January 7, 2011 4:41 PM | Report abuse

@BobMiller2,

I know you know where the model page is on this site. Go to the NAM and click on any hour. When the next screen pops up, look to the right and one of the last columns is called "Sim Radar Reflectivity". That is where you will find Wes's radar sim.

300 hours out on the GFS?? It may look nice and is nice to dream about but it is just that. A dream. If you believe it (which I don't think you do), I have a bridge I am trying to get rid of.

Let's concentrate on Tuesday and maybe the collective hopes of all us snow lovers is enough to give us a decent snow event.

Posted by: pjdunn1 | January 7, 2011 4:43 PM | Report abuse

On one of the previous posts, Wes (or maybe Jason) has an image that says "simulated radar for 7 am Saturday". Can someone post a link to a site that has this so-called simulated radar??
THANK YOU!!

Posted by: BobMiller2 | January 7, 2011 4:44 PM | Report abuse

pjdunn1

Thanks so much! Disregard the comment I just posted, I accidentally posted it again without realizing that you had answered it. :)

Posted by: BobMiller2 | January 7, 2011 4:48 PM | Report abuse

bbirnbau - Cool...and agreed.

Posted by: parksndc | January 7, 2011 4:48 PM | Report abuse

I have a question:
How come this afternoon it seems that the mets are starting to lean towards a storm developing for Tuesday? The models are still taking it off the coast, but some of the mets are pretty sure that the models aren't seeing the phasing with the plains feature like they should.
Can any of the gang explain the sudden boost in potential snow for Tuesday?
Posted by: bbirnbau | January 7, 2011 4:21 PM |
-----------------------------------------------------------------
bbirnbau-

It may be due to more model consistency... other than that, I don't know.

Posted by: BobMiller2 | January 7, 2011 5:03 PM | Report abuse

BobMiller, you can find the Sim Radar on the NAM at any run here (click time selection under NAM row -- most recent is 18z). It's on a few other models as well but not the GFS.

Posted by: Ian-CapitalWeatherGang | January 7, 2011 6:24 PM | Report abuse

AndrewRockville, I think there are some differences in this case which bring at least a little extra confidence that snow might be easier to come by. The major one is the fact that it starts as a fairly well developed system in and around the Gulf of Mexico. While it's not a classic (big storm) case of it moving up the coast and becoming very strong, you still get some of that thrown into the mix as the second piece of the puzzle (another shortwave to the west) comes along. So, where on Dec 26 we were very dependent on the storm to form quickly to give us moisture, this one already looks to have some to work with before it moves up (how far/strong?) the East Coast.

Posted by: Ian-CapitalWeatherGang | January 7, 2011 6:28 PM | Report abuse

Following up on a comment yesterday about back-to-back snowy winters, the pre 2009-10 record winter of 1898-99 of 54.4" was followed by 35.6" in 1899-1900.

http://forums.accuweather.com/index.php?showtopic=8952

Along with "Snowmaggdeon", which I hope arrives by next Tuesday, I just purchased a snow lottery ticket; numbers are
01 11 11

If I win, I'll split the winnings with Walter.

Posted by: JerryFloyd1 | January 7, 2011 6:29 PM | Report abuse

WWA up for points north & west.

From the National Wx Svc:

URGENT - WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
706 PM EST FRI JAN 7 2011

MDZ004-005-009-010-013-014-080815-
/O.CON.KLWX.WW.Y.0002.110108T0600Z-110108T1800Z/
FREDERICK MD-CARROLL-MONTGOMERY-HOWARD-PRINCE GEORGES-
ANNE ARUNDEL-
INCLUDING THE CITIES OF...FREDERICK...WESTMINSTER...
GAITHERSBURG...COLUMBIA...ANNAPOLIS
706 PM EST FRI JAN 7 2011

...WINTER WEATHER ADVISORY REMAINS IN EFFECT FROM 1 AM TO 1 PM
EST SATURDAY...

A WINTER WEATHER ADVISORY REMAINS IN EFFECT FROM 1 AM TO 1 PM EST
SATURDAY.

* PRECIPITATION TYPE...SNOW.

* ACCUMULATIONS...1 TO 3 INCHES.

* TIMING...LIGHT SNOW WILL BEGIN LATE TONIGHT. SNOW SHOWERS WILL
INCREASE IN INTENSITY SATURDAY MORNING BEFORE MOVING NORTHEAST
BY EARLY AFTERNOON.

* TEMPERATURES...MINIMA TONIGHT IN THE LOW 20S. MAXIMA SATURDAY
IN THE LOW 30S.

* WINDS...LIGHT AND VARIABLE TONIGHT. WEST-NORTHWESTERLY 10 TO
15 MPH SATURDAY WITH HIGHER GUSTS.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A WINTER WEATHER ADVISORY MEANS THAT PERIODS OF SNOW WILL CAUSE
TRAVEL DIFFICULTIES. BE PREPARED FOR SLIPPERY ROADS AND LIMITED
VISIBILITIES...AND USE CAUTION WHILE DRIVING.

Posted by: Havoc737 | January 7, 2011 7:26 PM | Report abuse

Whoops, capital weather team beat me to it with the 7:20 update.

Posted by: Havoc737 | January 7, 2011 7:28 PM | Report abuse

bbirnbau- Wes wrote a really solid technical discussion on a short wave rigde showing up on the GFS upper level flow maps for Tues-wed... He also talks about the ensemble all going west of the operational. Ian- I really like your analysis above... Think about what we had on Dec 22... in the southwest... just a peice of energy spinning around over AZ... four days out this time around we have Winter Storm watches posted for the majority of the south... we have so much more to "start" with here... the wild card is secondary low coming in from the NW... Could CWG provide some insightful analysis on what that is looking like?? Strength, timing, etc.. Thanks.. and again great analysis guys!

Posted by: jac8949 | January 7, 2011 7:51 PM | Report abuse

I'm seeing predictions of up to 7" for South Jersey tomorrow, 2-4" in Baltimore and a lame 1" here. Time for the ridging to start working in our favor!

Posted by: JerryFloyd1 | January 7, 2011 7:51 PM | Report abuse

Havoc737,

Why do you feel that you have to post the entire WWA in the comment section. May I politely ask you to n

Posted by: BobMiller2 | January 7, 2011 7:56 PM | Report abuse

Oops! Sorry, I accidentally hit submit before I finished typing my previous comment. This is what it's supposed to say:


Havoc737,

Why do you feel that you have to post the entire WWA in the comment section. May I politely ask you to not post an entire advisory/warning, but instead give a brief description? Thanks, BobMiller2

Posted by: BobMiller2 | January 7, 2011 7:59 PM | Report abuse

Oops! Sorry, I accidentally hit submit before I finished typing my previous comment. This is what it's supposed to say:


Havoc737,

Why do you feel that you have to post the entire WWA in the comment section. May I politely ask you to not post an entire advisory/warning, but instead give a brief description? Thanks, BobMiller2


Posted by: BobMiller2 | January 7, 2011 7:59 PM | Report abuse

--------------------------------


Who crowned you king?

Posted by: PlowKing1 | January 7, 2011 8:04 PM | Report abuse

JerryFloyd1,

I feel your pain. It seems as though the trend this winter is for the biggies to either pass too far south of us or develop too far north for us to see any substantial snowfall. Sigh. Oh well, there's always next winter. :)

Posted by: BobMiller2 | January 7, 2011 8:12 PM | Report abuse

@BobMiller2, as Yogi sez, it ain't over 'til it's over. All I ask is no snow biggie on 2.22, when I fly outta' here.

Posted by: JerryFloyd1 | January 7, 2011 8:15 PM | Report abuse

@ Bobmiller2:
Look, I don't know how long you've been posting here, and not to make you seem unwelcome, but with some of the inane content you've been posting, I hardly think that posting a full text from the NWS is all that bad.

Furthermore, as this is something I've done for the entirety of my time on capital weather (both the private blog and here on wapo), unless I hear directly from someone with capital weather gang to cease doing so, I will post timely relevant information as I see fit when the need arises, for the good of the readers of this blog.

Sorry if this seems a bit harsh.

Posted by: Havoc737 | January 7, 2011 8:18 PM | Report abuse

JerryFloyd1,

I hope you make it out OK on 2/22. Mid - late February, however, has proven itself to be one of the most favorable times for a good storm, though.

Posted by: BobMiller2 | January 7, 2011 8:19 PM | Report abuse

Havoc737,

Sorry. I didn't mean to offend anyone. I thought about it and you're right; you should have the right to post what you feel is appropriate just like I do.

Once again, sorry to bother you,
BobMiller2

Posted by: BobMiller2 | January 7, 2011 8:23 PM | Report abuse

Why does the WWA specifically exclude DC? If it's "urban heat island" effect, what about those of us who live in the northern corner of DC, where the weather more closely resembles that of, say, Silver Spring, than DCA? If it's geography, why is all of PG county under the WWA?

This is not the first time I've seen this happen with advisories, but I still don't get it.

Posted by: petworthlad | January 7, 2011 8:31 PM | Report abuse

jac8949,

Yeah I got around to Wes' discussion it was really helpful. I love it when mets verify theories I've made from my own uneducated arsenal. I always had believed throughout the past few days that the shortwave feature to the west was going to determine in large part whether or not we could get a decent snow Tues. I'm really pulling for those to phase in time.

But other than that, nice surprise for 1-3 inches tonight. Have some fun in the snow with my pup tomorrow.. hopefully we get 3 somehow.

Posted by: bbirnbau | January 7, 2011 10:04 PM | Report abuse

Interesting accumulation map from National Weather Service for region tomorrow: Map. Indicates 0.5-2+" in metro region.

Posted by: Jason-CapitalWeatherGang | January 7, 2011 10:27 PM | Report abuse

When will the snowfall be at peak intensity?

Posted by: samd95 | January 7, 2011 10:31 PM | Report abuse

Oh boy, I'm in the .25" area.

Posted by: VaTechBob | January 7, 2011 10:32 PM | Report abuse

What is the threshold for having a Winter Weather Advisory posted, 2"?

Most of PG County is under 2" in the latest NWS forecast map and yet the entire county has a WWA posted, whereas DC does not.

I'm not yet convinced we'll get more than a very light coating out of this. Maybe a half inch, like the Dec 26 "snow".

Posted by: JerryFloyd1 | January 7, 2011 10:51 PM | Report abuse

Jason--The NWS accumulation map you posted kind of answers my question about why DC is not under the WWA, since NWS only calls for 1" in DC, and since there is no Saturday rush hour, the "special" advisory criterion doesn't apply. Still doesn't explain why PG County is in the Advisory area, since NWS forecast also calls for 1" there...

Posted by: petworthlad | January 7, 2011 10:51 PM | Report abuse

Maybe Laurel gets 2" according to that map. And Old Bowie. But yeah, Prince Georges County generally seems to be outside the 2" potential based on the NWS forecast map. I wouldn't be surprised if we get more like a 1/2". It seems to me that predicting 0.10" or less qpf could just as easily mean a mere dusting as it may mean an inch.

Posted by: BH99 | January 7, 2011 11:06 PM | Report abuse

What do the latest models say about the Tuesday threat?

Posted by: samd95 | January 7, 2011 11:17 PM | Report abuse

samd95,

This link takes you to a site that has all the models you could possibly want - - GFS, NAM, Euro, etc. You may want to read the tutorial as it can be a bit overwhelming at first.

http://www.meteo.psu.edu/~gadomski/ewall.html

This next one is a bit easier to use, but only has the American models.

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/

Hole this helps!

Posted by: BobMiller2 | January 7, 2011 11:24 PM | Report abuse

Watching Bob Ryan just now, he thinks that parts of PG county (along with AA county) will probably see higher amounts due to some strengthening of low over water (I assume he meant the Atlantic, not the Chesapeake!). But I could swear I heard him say something about the Winter Weather Advisory being posted for a county when the NWS expects at least 50% of the county to fit the criteria.

Posted by: petworthlad | January 7, 2011 11:27 PM | Report abuse

Currently some light snow falling in the Blue Ridge Mtns east of Front Royal. 22.5F

The 0z GFS looks to me like a period of light to moderate snow next Tuesday giving us a few inches...

Posted by: spgass1 | January 7, 2011 11:28 PM | Report abuse

petworthlad: I don't think, in this case, that the "heat island effect" is a factor at all. It's just that the models develop this system to a greater degree once it gets N and E of us, putting the eastern suburbs on the western edge of the best "lift," or snow potential.

Posted by: Don-Capital Weather Gang | January 7, 2011 11:32 PM | Report abuse

So much for driving my kid back to school in PA tomorrow.

Posted by: meta2 | January 7, 2011 11:39 PM | Report abuse

Most of the latest models r moving the L a little closer 2 the coast. Hopefuly this will cont. 2 b the trend.

Posted by: VaTechBob | January 7, 2011 11:43 PM | Report abuse

Update: dusting so far, but diminishing to flurries for now... Good night.

Posted by: spgass1 | January 7, 2011 11:45 PM | Report abuse

@petworthlad

I agree PG county's inclusion is odd if DC is excluded - although NWS is probably thinking the NE part of PG county may meet the criteria, so just included the whole county.

Posted by: Jason-CapitalWeatherGang | January 7, 2011 11:48 PM | Report abuse

Thanks Don & Jason. I guess if part of the county goes under the advisory, so goes the whole county. (Unless one lives in one of those special places like the "City of Falls Church," or the "City of Alexandria."

Appreciate the replies guys, and keep up your great work!

Posted by: petworthlad | January 7, 2011 11:53 PM | Report abuse

I guess the local Meteorologist is not saying much about the latest storm on Tuesday, I guess someone on this thread will say something, but not that much on here thus far..... as far WWA, I'm wondering if tomorrow morning the NWS will expand the WWA for the District......

Can someone analysis the storm for Tuesday for the latest model run??

Posted by: MNguyen6551 | January 7, 2011 11:58 PM | Report abuse

The NWS does break down some Virginia counties... maybe because of their size and differing climatology, e.g. NORTHERN FAUQUIER-SOUTHERN FAUQUIER-WESTERN HIGHLAND-
EASTERN HIGHLAND

Posted by: spgass1 | January 8, 2011 12:01 AM | Report abuse

MNguyen6551, right now it's looking like a fairly weak event, 1-3 inches according to the models. But keep your fingers crossed.

Posted by: bbirnbau | January 8, 2011 12:13 AM | Report abuse

bbirnbau - Wow, talking about Tuesday? A big difference from I guess last night/early Today Model Runs, what I heard..... If it's only 1-3 Inches then that's almost or similar to this so called "Storm" for Saturday, but I'm still keeping hope this storm will dump at least 5 Inches or more on Tuesday.... I guess the Coastal Low for Tuesday isn't going to be close to coast or the storm isn't going to be that strong enough.....

Posted by: MNguyen6551 | January 8, 2011 12:19 AM | Report abuse

I would like to report 5 snowflakes in Waldorf, MD. We had 3 snowflakes at 3AM and now that its 430, we have 5.

Posted by: IGotLotsToSay | January 8, 2011 4:37 AM | Report abuse

I would like to report 5 snowflakes in Waldorf, MD. We had 3 snowflakes at 3AM and now that its 430, we have 5.

Posted by: IGotLotsToSay | January 8, 2011 4:37 AM | Report abuse

I would like to report 5 snowflakes in Waldorf, MD. We had 3 snowflakes at 3AM and now that its 430, we have 5. Weather is still VFR for flights. I think snowremoval on the runways are doable-a leaf blower should work.

Posted by: IGotLotsToSay | January 8, 2011 4:39 AM | Report abuse

woops! Explorer was locked up-sorry for the repeats! But the last one I submitted is the most up to date and very helpful for airport snow removal operations.Please ensure airport officials get word to man their runway crews with the appropriate leaf blowers..or brooms.

Posted by: IGotLotsToSay | January 8, 2011 4:42 AM | Report abuse

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