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Posted at 2:55 PM ET, 10/27/2010

Initial storms exit, tornado watch scaled back

By Jason Samenow

Flash flood warning for District discontinued

* Outlook thru weekend: Full Forecast | Midwest storm by the numbers *

Though tornadoes did not materialize overnight, the atmosphere remains humid and unstable and thunderstorms capable of rotating may once again develop this afternoon. The Storm Prediction Center has issued a tornado watch for much of the metro region (map) until 8 p.m., excluding the far western suburbs.

2:55 p.m. update: The tornado watch has been canceled for Prince William, Fauquier, Fairfax, and Montgomery counties as well as the District. But the watch remains in effect in Prince George's and Stafford counties, as well as bordering counties to the south and east. Also, the flash flood warning that had been in effect for the District and close-in suburbs has been discontinued.

Remember that a tornado watch is issued when weather conditions are favorable for severe thunderstorms to produce tornadoes in and close to the watch area. It is not a guarantee that tornadoes, which are relatively rare in this area, will form.

2:40 p.m. update: With the exception of Charles county, where some thundershowers linger, the rains have ended across the metro region. There's a 40% chance of additional activity the rest of the afternoon and evening, with the best storm chances east of D.C. towards the Bay.

Keep reading for earlier updates...

From 2:00 p.m.: Though a Flash Flood Warning remains in effect for the District and close-in suburbs, the rain has stopped for the time being across much of the area except the east and southeast suburbs. A nasty thunderstorm continues to impact northern Charles county and southern PG county, where a severe thunderstorm warning remains in effect until 2:15 p.m. This storm should move into Calvert and Anne Arundel counties in the next 30 minutes.

Everyone else in the metro region should catch a break for the next hour or two, but it's not out of the question additional showers and storms develop late this afternoon into the early evening.

From 1:30 p.m.: A severe thunderstorm warning has been issued for southern Prince George's county and northern Charles county, including La Plata until 2:15 p.m.. Weather service says storm could produce winds in excess of 60 mph. The storm in northern Charles county is the most intense so far today and has the potential to rotate and generate a tornado - though no tornado warning has yet been issued. Stay tuned.

From 1:15 p.m.: The story with the storms so far has been the rain not the wind. Doppler estimated rainfall totals suggest 0.75-1.25" has fallen from central Prince William county through central Fairfax county and into downtown D.C. in under an hour. These heavy rains have prompted the issuance of a Flash Flood Warning for the District and immediate close-in suburbs (Arlington, E Central Fairfax, SE Montgomery and W Central PG counties, Alexandria, and Falls Church)

The current line of storms is progressing to northeast with the strongest activity in extreme eastern Prince William and Fairfax counties. This activity is headed into southern Prince George's county. In the next 45 minutes or so, the District and points to the south and west should see the rain stop or mostly diminish - at least for the next couple hours.

From 12:45 p.m.: A line of thunderstorms with locally very heavy rain is covering Fairfax county, the District, western Prince George's county, and eastern Montgomery county. The line then extends southwest into western Prince William and eastern Fauquier counties. This line is moving northeast, with some areas getting "trained" by multiple storms within this same line. Thus, localized flash flooding is possible. So far, no tornadoes have developed.

From 12:15 p.m.: Strong thunderstorms - with torrential rain - are currently moving through western Fairfax county and will head northeast impacting D.C. and Montgomery County in the next hour. So far, these storms have not produced reports of severe weather and no warnings have been issued. But storms may grow more intense this afternoon - especially east of I-95.

From 11:55 a.m.: NOAA's Storm Prediction Center has just issued a special statement [bold text indicates emphasis added] that it is:

MONITORING FOR AN INCREASING SURFACE BASED SEVERE POTENTIAL THIS AFTERNOON WITHIN A SOUTHWEST-NORTHEAST CORRIDOR FROM NORTHERN NC AND CENTRAL/EASTERN VA INTO DE/EASTERN MD AND NJ/SOUTHEAST PA. A TORNADO WATCH WILL BE COORDINATED SOON.

...

MODERATE LOW LEVEL TURNING AND OTHERWISE RATHER STRONG DEEP LAYER SOUTHWESTERLY FLOW WOULD BE VERY SUPPORTIVE OF BOTH SUPERCELLS AND SMALL SCALE BOWING SEGMENTS...WITH ASSOCIATED POTENTIAL FOR WIND DAMAGE/TORNADOES.

meso-102710.jpg
Image highlighting region where issuance of tornado watch by NOAA's Storm Prediction Center (SPC) is likely. Source: NOAA's SPC

By Jason Samenow  | October 27, 2010; 2:55 PM ET
Categories:  Alerts, Updates  
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Next: PM Update: Storms out, fog in

Comments

Torrential rains in Manassas. Fortunately I had sweatpants in the car after I got drowned coming back from lunch. They look great with the collared shirt.

Posted by: rocotten | October 27, 2010 12:12 PM | Report abuse

Wow. It is gonna rain like **&$*&(*&$ here in Falls Church for next hour. Just started a few mins ago, and radar shows a load coming...

Posted by: KPosty | October 27, 2010 12:15 PM | Report abuse

Watch issued, mainly D.C. and east.

Posted by: Ian-CapitalWeatherGang | October 27, 2010 12:16 PM | Report abuse

I too, got caught in the torrential manassas downpour, and I don't have any dry clothes! Luckily only one other person in my office, who looked surprised and said, Oh, is it raining out there?

Posted by: weathergrrl | October 27, 2010 12:21 PM | Report abuse

Flash flooding in Manassas.

Posted by: rocotten | October 27, 2010 12:24 PM | Report abuse

The red turning yellow in the last loop.

I think it is doing its imitation of traffic on 28 North when it reaches Fairfax County :-)

Posted by: jaybird926 | October 27, 2010 12:31 PM | Report abuse

Currently a lovely shade of green out there in Adams Morgan... winds are picking up.

Posted by: CuseFan07 | October 27, 2010 12:33 PM | Report abuse

Pouring it's butt off here in Franconia. Might need a kayak to get home tonight.

Posted by: FusilliJerry1 | October 27, 2010 12:49 PM | Report abuse

Raining in Silver Spring. Looks like driving to Kinkos and Post office rather than walking.

Posted by: epjd | October 27, 2010 12:53 PM | Report abuse

Getting a good medium soaking in Alexandria.

We're inching closer to the year to date normal.

Posted by: jaybird926 | October 27, 2010 12:55 PM | Report abuse

Freight train of rain seems to be rolling right down the middle of the DC metro area.

Posted by: jojo2008 | October 27, 2010 12:57 PM | Report abuse

Heavy rain in Fairfax City right now. No thunder, though, and the wind has been pretty calm.

Posted by: figgy_va | October 27, 2010 1:00 PM | Report abuse

Torrential rains for the last hour in Oakton easing up as first large cell moves ENE. Looks like more training cells SW, in Prince William/Stafford/Fauquier counties, headed this way behind it.

Looks like DCA is going to get quite a rain total today.....not sure about Dulles or BWI.

A smaller, weaker line of showers off to the W, along the Blue Ridge, with the front itself, but doesn't look like much...most of the energy seems to be 50-60 miles east of the front, more or less along I-95.

Posted by: MMCarhelp | October 27, 2010 1:02 PM | Report abuse

raining pretty heavily near union station..

Posted by: madisondc | October 27, 2010 1:04 PM | Report abuse

Unbelievable dewpoints for late October....no wonder we're getting tropical downpours.

Posted by: MMCarhelp | October 27, 2010 1:04 PM | Report abuse

starting to get cooler. think our high has been reached.

by the way, is there a place to get hour by hour temps, say for today up to the hour, or something close?

Posted by: jaybird926 | October 27, 2010 1:10 PM | Report abuse

Pouring again in Ballston with numerous power blinks.

Posted by: Stevis16 | October 27, 2010 1:12 PM | Report abuse

Here at Ft. Belvior we spotted what we thought were funnel clouds trying to form on the southwestern edge of the storm. Fortunately though they did not get enough rotation to really form but it was sure scary for a few minutes.

Posted by: HokieAnnie | October 27, 2010 1:14 PM | Report abuse

Intermittent heavy downpours here, no thunder, but lightning was reported in the Manassas/Culpeper area as the storm was approaching.

Posted by: Bombo47jea | October 27, 2010 1:22 PM | Report abuse

hourly observations (3 day history) available from NWS, DCA for example:

http://www.weather.gov/data/obhistory/KDCA.html

Posted by: dtkwx | October 27, 2010 1:28 PM | Report abuse

@jaybird926

dtkwx is correct... and in fact, you can access those observations for various locations using the "Current Conditions" link in the "Links" box on the left sidebar of this page.

Posted by: CapitalWeatherGang | October 27, 2010 1:31 PM | Report abuse

Home w/my little guy (6 yr old) today. Got VERY dark here when the rain went thru. Little wind, heavy rain, that's it. Just got a LOT brighter outside. This isn't the last of the rain we'll see, is it? Hope this brightness doesn't further de-stabilize the atmosphere.

Posted by: southbridgemom | October 27, 2010 1:32 PM | Report abuse

Now lightly raining here in TP/SS area. Have picked up about a half-inch from this lastest round, and 1.12" since midnight.

Posted by: steske | October 27, 2010 1:36 PM | Report abuse

Sunny in Chantilly (Westfields area). Rained like heck from noon to one though.

Posted by: wiredog | October 27, 2010 1:36 PM | Report abuse

If you're enjoying today's violent weather, just wait - as it will get much worse. What to do? Invest astutely:

Posted by: bobcoco | October 27, 2010 1:55 PM | Report abuse

Sunny in Southbridge as well.

Posted by: southbridgemom | October 27, 2010 1:56 PM | Report abuse

Sunny and warm in Laytonsville, MD, after some moderate rain.

Posted by: dprats21 | October 27, 2010 2:03 PM | Report abuse

To read a prophetic editorial about how to profit from the cause of this weather - Global Warming - go to the radfilms.com website.

Posted by: bobcoco | October 27, 2010 2:09 PM | Report abuse

The Vienna Halloween parade is tonight, kids line up at 6:30pm, the parade starts at 7pm. There are going to be a lot of disappointed kids/adults if it is miserable out.Is it going to be awful?

Posted by: bettylou1 | October 27, 2010 2:11 PM | Report abuse

Got a quick .9" here in Falls Church in the past 2 hours, for 1.65" since midnight

Posted by: KPosty | October 27, 2010 2:17 PM | Report abuse

Got dark for the downpour, then the sun shone, then getting pretty cloudy again here in Old Town Alexandria. (The contrast between the mostly blue sky on the left side of the office window, to the thick clouds on the right, is striking.) Not sure we're done yet...

Posted by: MKoehl | October 27, 2010 2:36 PM | Report abuse

NWS really seems to be jumping the gun on these tornado watches this summer...

Posted by: mickb1 | October 27, 2010 3:00 PM | Report abuse

..and fall.

Posted by: mickb1 | October 27, 2010 3:03 PM | Report abuse

NWS wasnt messing around - we basically just went through an outer feeder band of a tropical system that was bottoming out at 950 or so mb...there was so much spin in the atmosphere that they warned almost every cell in the midwest yesterday and were spot on to give our area a watch for both events due to the dynamics in place. NWS doesnt throw tornado watches around like spare change. This outer band had a history of producing cells that had rotation for two plus days. Kudos to them for making us pay attention.

Posted by: DullesARC | October 27, 2010 3:12 PM | Report abuse

Looking at Mosaic, there are still bands moving NEward from the NW Gulf of Mexico. When is the front gonna' push all this precip outta' here? Or maybe the last batch was the rain train's caboose?

Posted by: JerryFloyd1 | October 27, 2010 3:36 PM | Report abuse

Thanks dtkwx and CWG for the hourly link.

I was right, btw, the temp dropped six degrees from 12 to 1! (Best weather gauge ever invented -- the window :-)

By the way, I noticed the hourly mark is given at :52.

Any reason for that?

Thanks.

Posted by: jaybird926 | October 27, 2010 4:06 PM | Report abuse

This was no tropical system but an extremely wound-up, potent extratropical system, though a Pacific typhoon might have fed energy into the original storm system. As for feeder bands, the sentiment here is that feeder bands represent a convergence of bow echoes which begin spiraling around each other, then forming and converging around a circular eyewall. It appears that in any case the storms pull high winds down to the surface from higher altitudes.

Winds measured from reconaissance or hurricane hunter aircraft are generally at flight level and are faster than surface winds which tend to get slowed by friction.

Posted by: Bombo47jea | October 27, 2010 11:42 PM | Report abuse

The comments to this entry are closed.

 
 
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