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Posted at 11:35 PM ET, 05/27/2010

Strong to severe storms possible overnight

By Ian Livingston

Damaging winds, hail, and flash flooding a risk

* Flash Flood Watch thru tonight (map) *
* A cirrus and contrail display | Video: Angry weather caller *
* Outside now? Radar, temps & more: Weather Wall | BeachCast *

***Update, 11:30 p.m.: The storms have weakened some as they've reached the District and no warnings are currently in effect in the metro area. They'll continue moving east southeast through the eastern suburbs in the next 30 minutes to an hour. A few more scattered showers and storms are possible elsewhere over the next couple hours, but the severe threat is diminished. ***

Update, 11:00 p.m.: Storms continue to pound the western suburbs -- particularly Fairfax County. Reports on Twitter of severe lightning (from Leesburg) and "A LOT" of hail in Fairfax City. Estimated time of arrival for storms in the District is 11:30 p.m.

Update, 10:30 p.m.: A intense line of thunderstorms has developed in the western suburbs and will move through the metro area in the next 90 minutes. Very heavy rain, gusty winds, dangerous lightning and some hail are possible with these storms.

Severe Weather Tracking Station
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Radar: Latest D.C. area radar loop shows movement of precipitation over past three hours. Powered by HAMweather. Refresh page to update. Click here to see radar bigger.
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Warnings: Severe alerts from National Weather Service. Updates w/o refresh (most browsers). Hint: Alert on map? Click matching label in key for details.

Keep reading for the forecast update posted earlier this afternoon through tomorrow and a summary of NOAA's hurricane outlook issued today. See David Streit's full forecast through Memorial Day. And if you haven't already, join us on Facebook and follow us on Twitter.

From earlier: Heat hit us again in a big way today, and now the stage is set for potential big storms as well. Any storms that do form will have plenty of fuel to feed off of after today's sunshine, and whatever passes through could be severe.

Tonight: Isolated storms may form across the area late this afternoon or early evening before additional, more widespread, activity heads toward us after sunset. Despite the heat and humidity, it is not a given that everyone will see storms. However, any storms that do move through could be severe with strong winds, hail and even some flooding. Events like this often produce a lot of lightning as well, so be on the lookout for such. Lows drop to the mid-and-upper 60s.

Tomorrow (Friday): Some remnants of overnight activity could persist until around sunrise, then we may see a bit of a lull before more showers or thunderstorms pop up during the day. Much of the activity tomorrow should be relatively light and scattered, but the potential for heavier rain rises during the late day, possibly lasting into the overnight. Highs should mainly reach the mid-70s, perhaps some upper 70s as well.

NOAA hurricane forecast: The National Oceanic and Atmospheric Administration (NOAA) is calling for an "active to extremely active" hurricane season. In a press conference today, NOAA forecasters announced that there is a 70 percent probability of 14 to 23 named storms, 8 to 14 hurricanes and 3 to 7 major hurricanes. Current averages are 11 named storms, six hurricanes and two major hurricanes.

By Ian Livingston  | May 27, 2010; 11:35 PM ET
Categories:  Forecasts  
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Next: Forecast: Cooler & gray today, then slowly nicer

Comments

Looks like some sort of boundary to the east of D.C. moving west, may kick something off around here in a bit. Also looks like a bit of a cell firing SW of balt though quite small right now.

Posted by: Ian-CapitalWeatherGang | May 27, 2010 3:33 PM | Report abuse

Any chance you guys might be working on a post about how the oil spill and hurricane season will affect each other? Obviously storm surge could push oil much further inland than the regular tide would but could oil be "picked up" by the storm and then rained out over land? Does the oil in the water affect how a hurricane would develop and strengthen?

Would love to hear anyone's thoughts on these items!

Posted by: ana_b | May 27, 2010 3:52 PM | Report abuse

posted something similar 2 threads back, but they're coming fast and furious...

are we gonna get hit by something that "pops up" just to our west? i see the storms way out in WV, but those are barely moving. and they haven't even crossed rt.81. at this rate they won't get here 'til sometime tomorrow....

Posted by: walter-in-fallschurch | May 27, 2010 3:56 PM | Report abuse

Storm SW of Balt (headed this general direction) growing nicely now, may head severe quick if it pops through the "cap". That boundary may be the front?

Posted by: Ian-CapitalWeatherGang | May 27, 2010 3:57 PM | Report abuse

walter-in-fallschurch, the stuff to the west should not hit us directly, maybe an outflow boundary could get more going. Ours should either pop overhead (nowish) or come in from the north later.

Posted by: Ian-CapitalWeatherGang | May 27, 2010 4:00 PM | Report abuse

ian,
gotcha. are these atypical for thunderstorms? don't they usually com in from the west?

Posted by: walter-in-fallschurch | May 27, 2010 4:10 PM | Report abuse

Posted by: Stevis16 | May 27, 2010 4:23 PM | Report abuse

walter, it is somewhat unusual I think. The backdoor front is acting as the main forcing mechanism and boundary and that's moving in from the east. The upper flow is pretty light but it's almost due north/south right now. Here's an update to the watch just out from SPC. Looks like the cap is holding strong for now around here, cell closeby has weakend a good bit.

Posted by: Ian-CapitalWeatherGang | May 27, 2010 4:24 PM | Report abuse

What is "the cap"?

Posted by: wzitlau | May 27, 2010 4:58 PM | Report abuse

Posted by: walter-in-fallschurch | May 27, 2010 5:12 PM | Report abuse

btw, thanks ian.

Posted by: walter-in-fallschurch | May 27, 2010 5:15 PM | Report abuse

wzitlau, a "cap" is a warm layer above the surface which keeps air from rising to its full potential -- storms form when warm air rises into cooler air above. In a lot of cases a cap actually helps produce stronger storms because it takes more energy to "punch" through it and when it happens you can get explosive development, but it can also keep things from ever forming despite "good" setup. This short vid might be helpful to visualize it.

Posted by: Ian-CapitalWeatherGang | May 27, 2010 5:16 PM | Report abuse

I guess these are real "pop-up" storms, because of the backdoorness. They seem to appear and move any which way. At least on radar. The cluster over West Virginia looks like a bloomin' onion.

Posted by: Groff | May 27, 2010 5:51 PM | Report abuse

Looks like we've broken the cap at least partially. Severe storm in MoCo.

Posted by: Ian-CapitalWeatherGang | May 27, 2010 6:03 PM | Report abuse

Look at the latest visible satellite loop- the frontal boundary is clearly visible and arc westward. Very unusual indeed. The MoCo storm is right on the edge of that...

Posted by: CM_in_Fairfax | May 27, 2010 6:08 PM | Report abuse

ian,
that was a good video.

"severe storms in MoCo"

i see that on the radar.

so now that "the cap" has been broken in MoCo, does that mean warm air will "seek out" that break? i.e., are we here in falls church less likely to see anything, now that the cap's been broken elsewhere?

Posted by: walter-in-fallschurch | May 27, 2010 6:15 PM | Report abuse

walter, I don't think so -- not less likely that is. Though these are all just pulsing right now, we'll see if we can get into the better dynamics as the evening wears on. Usually once you see the cap erode a bit the whole thing will go, but we don't have a lot of "trigger" right now, which is why they are all near the front/boundary. Cell in Howard may go svr soon, other seems to have died off.

Posted by: Ian-CapitalWeatherGang | May 27, 2010 6:26 PM | Report abuse

Seems to be very spotty coverage right now.

Posted by: MKadyman | May 27, 2010 6:43 PM | Report abuse

I would not be too confident we get a lot more over most of the area. The stuff north could easily miss to the east.

Posted by: Ian-CapitalWeatherGang | May 27, 2010 6:54 PM | Report abuse

Driving east through Chevy Chase and downtown Silver Spring I saw a tall cumulonimbus cloud to the east and north. What looked like an anvil was stretching toward me and seemed close to overhead for part of my drive. I don't know how far it was but it was quite impressive. It made me wish I had a camera. Next to no rain on my drive home.

Posted by: Murre | May 27, 2010 7:34 PM | Report abuse

boy oh boy....

i can imagine the disappointment i'd be having if we were "promised" the snow equivalent of 2" hail and 70 mph wind and we got what it appears we're going to get....i.e. NOTHING in falls church....boy oh boy....

but, since it's just rain, who gives a darn!

at least i didn't have any inconvenient, costly and dangerous weather this afternoon/evening....

Posted by: walter-in-fallschurch | May 27, 2010 7:37 PM | Report abuse

very stable out there. I am surprised more did not pop.

Posted by: Camden-CapitalWeatherGang | May 27, 2010 7:37 PM | Report abuse

Beautiful sunset over here in upper MoCo. Sun is just peaking below the clouds. Hope others can see this.

Posted by: dprats21 | May 27, 2010 7:59 PM | Report abuse

Talk about BUST!!!!!!!!!!!!!

Posted by: hikeguy23 | May 27, 2010 8:17 PM | Report abuse

Very little shear, probably noted the clouds went straight up in most cases. Mix that with a cap and we may end up wasting extreme surface instability. The needed "cold pool" associated with the bigger complex ended up to far east it seems to target us properly. Similar (but more extreme) output happened last night in New England and is actually sort of again tonight but probably too far northeast to make it in. Convection is one of the most difficult weather items to forecast in advance. I'm not sure I'd say it's a total bust except that maybe the NWS/NOAA was a little too robust with the watches.

Posted by: Ian-CapitalWeatherGang | May 27, 2010 8:30 PM | Report abuse

Hearing some thunder in Warren Co... lights flickering...

Hi today 86 after an overnight low of 66. Currently 73 and windy w/ rain starting to fall...

Posted by: spgass1 | May 27, 2010 8:50 PM | Report abuse

update: pea sized hail mixing in w/ the thunderstorm

Posted by: spgass1 | May 27, 2010 9:01 PM | Report abuse

Is that Warren Co. just west of Fauquier on the map? Looks like a nasty cell out there...

Posted by: natsncats | May 27, 2010 9:06 PM | Report abuse

yes, the county where 66 meets 81

Posted by: spgass1 | May 27, 2010 9:09 PM | Report abuse

Radar out of Sterling looks cool right now. You can see the downdraft of the earlier MoCo. storm shooting out to the west, and headed toward that serious looking storm out near the Blue Ridge. Wondering if maybe the best is yet to come.

Posted by: curtmccormick | May 27, 2010 9:14 PM | Report abuse

Small cells now starting to fire Metro-west.

Posted by: Brian-CapitalWeatherGang | May 27, 2010 9:40 PM | Report abuse

Nothing too spectacular, but here's a picture of hail on the deck.

Still hear some decent boomers... temp has dropped to 58.5.. 15 degrees in less than an hour

Posted by: spgass1 | May 27, 2010 9:44 PM | Report abuse

Low thunder now beginning to be heard in Lake Ridge. The cat (who hates thunderstorms) just slunk under the bed, so something is coming...whoa! There's a wall of water outside that arrived in a matter of seconds.

Posted by: meta2 | May 27, 2010 9:55 PM | Report abuse

I can see some distant lightning behind the clouds and hearing a few deep rumble here in Alexandria. The wind sure has picked up. spgass, I love the wildlife webcam!

Posted by: AnneinSand | May 27, 2010 10:03 PM | Report abuse

Rain steadily picking up over the past few minutes in Vienna. Severe storms moving through Manassas and should be heading our way within the hour.

Posted by: map408 | May 27, 2010 10:21 PM | Report abuse

Heavy rain and thunder in Herndon. I am glad the weather was stable until I got home. I parked at 10pm or so and right away it started raining. Felt like we got some hail too, though I couldn't see it.

Posted by: RoseVA | May 27, 2010 10:41 PM | Report abuse

Rockin' in Annandale with heavy rain and thunder.

Posted by: VAOrangeFish | May 27, 2010 10:51 PM | Report abuse

Downright pouring in Oakton, with loud thunder, lightening, and intermittent small hail.

Posted by: punyandy | May 27, 2010 10:55 PM | Report abuse

disregard my last post about "nothing in falls church"! the sky is falling here.

Posted by: walter-in-fallschurch | May 27, 2010 11:06 PM | Report abuse

Great summer T-storm here in 7 Corners - power should be out shortly!

Posted by: koggly | May 27, 2010 11:09 PM | Report abuse

Been thundering on and off here for about 30-40 minutes. Raining now in Dumfries, it's hitting our DirectTV dish and we can't get the local news. Let the games begin...

Posted by: southbridgemom | May 27, 2010 11:16 PM | Report abuse

I was out driving just before the storm hit in Reston, VA, and I honestly thought that it would miss us. Out of nowhere though, a cell popped up (Which closed the gap), and it hit us. Fortunately, we missed the really bad stuff (I received a report that Hail was setting off car alarms in Clifton, VA, and it was grape sized (Radar indicated 0.50 in. diameter Hail)).

Now it's starting to train some with the convection out west, but so far it isn't forming into the severe range.

Posted by: TheAnalyst | May 27, 2010 11:16 PM | Report abuse

We just received 0.64 in. of precipitation within the past hour, and the temperature dropped from 80 Degrees Fahrenheit, to 65 Degrees Fahrenheit!

Posted by: TheAnalyst | May 27, 2010 11:19 PM | Report abuse

Centreville VA Serious T-storm for last hour. No hail though....just buckets of water with lightning/booming thunder overhead.
I should have known that when I went out to water the flowerpots heavy rainfall would be here within 2 hours. That is almost as good a rain initiation strategy as washing the car.

Posted by: FIREDRAGON47 | May 27, 2010 11:23 PM | Report abuse

Just got about 10-15 minutes of heavy downpours, thunder and lightning in SE Washington DC, now it's abating. The gutters were gushing!

Posted by: jantos2 | May 27, 2010 11:45 PM | Report abuse

I was jolted out of bed by a very intense thunderstorm. This is one of the heaviest I have seen in some time in terms of rain, lightning, and thunder.

Posted by: david_in_stafford | May 27, 2010 11:49 PM | Report abuse

flat, 3/4" hailstones covered the ground at the Vienna Metro station. Severe, but mostly not close, lightning. Estimated 45-50 MPH gusts.

Posted by: MMCarhelp | May 27, 2010 11:59 PM | Report abuse

Concerning my earlier post, you guys were right. It DID stay unstable well into the night....surprisingly so.

Around 10:30, I looked at that huge zone of purple in the middle of those storms west of me (I'm in Vienna) and thought "Holy S***". Figured hail around golf-ball size. I don't have cover for my car at my house, and didn't want to risk large hail, so I jumped in my car and rode it out in the South Metro parking garage (you don't have to pay to get out if you use the west entrance...there are metered spaces in front of the gates). We actually got 3/4" flat stones there, covering the ground, but I'm sure there was larger hail just west of there.

Posted by: MMCarhelp | May 28, 2010 12:06 AM | Report abuse

This was the hail dropping around 10:20pm in northern Manassas, VA. http://twitpic.com/1rowka

Posted by: bbrumbel | May 28, 2010 8:07 AM | Report abuse

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