* Severe thunderstorm watch until 9 p.m. for areas southeast of Washington *

5:45 p.m. final update: The worst of the weather has passed south and east of the Beltway. The most intense storm that was sweeping through Annapolis is pushing over the Bay.  The threat of severe weather from around the Beltway and and to the north and west has come and gone and the Weather Service has dropped the severe thunderstorm watch in this area.

Looking ahead, the one region that could still see a severe storm includes Southern Maryland, in Calvert and St. Mary’s County. Elsewhere, a few lingering pop up showers and storms are possible through 9 p.m. or so, but should not be severe.  This is good news if you’re headed to the James Taylor concert.

For additional forecast details for tonight through the weekend, look for our PM Update, to be published around 6 p.m.

Below, see some more telling photos of tonight’s storms and scroll down to review earlier storm coverage…

5:30 p.m. update: A severe thunderstorm warning is in effect in Anne Arundel County for the area around the Annapolis until 6:15 p.m. If you’re headed toward the eastern shore, you may want to wait to until these storms pass as they are extremely heavy with lots of lightning and perhaps some pockets of damaging winds.

5:15 p.m. update: ABC7 reports some impressive rainfall totals, in a very short amount of time, from these storms:

In downtown Washington, as the storms came through, we picked up a quick 0.47 inches at The Washington Post.

Meanwhile, Seat Pleasant in Prince George’s County, near Landover, reported a wind gust to 58 mph.

5:07 p.m. update: In the storms that swept through Fairfax County earlier, some trees did come down in McLean, Oakton, Vienna, and Fairfax. Winds gusted to 48 mph at Reagan National Airport as the storm blew through.

Some tree damage was photographed in the District as well.

4:56 p.m. update: As the intense storms roll east, a severe thunderstorm warning has been issued for our eastern suburbs, including central and southern Prince George’s County, southwest Anne Arundel County, and northwest Calvert County. Torrential rain is likely and pockets of damaging wind are possible as these storms push east through this area.

4:53 p.m. update: As downtown Washington is deluged, the temperature has dropped 17 degrees in 15 minutes.

4:45 p.m. update: The severe thunderstorm warning for northwest Washington and areas to the west and northwest has been canceled as the worst weather has moved southeast. A warning remains in effect for downtown Washington and areas to the southeast.

Here are some photos/video of the storm:

4:30 p.m. update: A severe thunderstorm warning has been issued for the southern half of the Beltway, including downtown Washington, eastern Fairfax County, and western Prince George’s County until 5:15 p.m. Torrential rain is likely  and damaging wind gusts are possible.

Essentially the entire immediate D.C. metro area is under a  storm warning now.

Doppler radar has indicated the potential for microbursts and wind gusts up to around 60 mph around Tysons, Mclean, and Arlington. Please head inside and take these storms seriously.

4:15 p.m. update: A severe thunderstorm warning is in effect through 5 p.m. for northwest Washington and its immediate western suburbs in southern Montgomery County and northern and central Fairfax County. Extremely heavy rain and strong winds are possible as the storm comes through.

Original post

(This post, originally published at 12:30 p.m., was updated at 1:20 p.m. to note a severe thunderstorm watch may be issued, and at 1:45 p.m. to note watch issuance, and 3:40 p.m. as storms started erupting.)

The air is super humid and a cold front is coming at us. Take these two factors together and it’s a recipe for some strong to severe thunderstorms in the region late this afternoon and evening.

Locally torrential rain, dangerous lightning and a few pockets of damaging winds are the most likely threats and the National Weather Service has issued a severe thunderstorm watch for the region until 9 p.m.

A severe thunderstorm watch means conditions are favorable for severe storms to develop, and to stay alert. If a severe thunderstorm warning is issued, on the other hand, it means a severe thunderstorm is imminent or already occurring and to seek shelter.

Isolated showers and storms could begin breaking out in the early to mid-afternoon hours, but most of our computer model guidance suggests storms are likely to be most numerous between about 4 and 7 p.m.

At 3:30 p.m., storms were erupting in the far western suburbs of Washington and likely to move through the immediate region during afternoon-evening commute.

Radar simulation from HRRR model between 4 and 9 p.m.

For folks attending the James Taylor concert at Nationals Park this evening, we’re hopeful most of the storms will have exited by 7 p.m., but we cannot rule out the chance for some lingering shower and storm activity through 8 or 9 p.m. Certainly, if you plan to enter Nationals Park when the gates open at 5 p.m., be prepared for storms and to shelter under the concourses, if necessary.

Chance of storms: 70 percent
Coverage: Scattered to widespread
Timing: 3-8 p.m.
Threats:

  • Torrential rain: Medium-High
  • Lightning: Medium
  • Damaging winds: Low-Medium
  • Flash flooding: Low-Medium
  • Large hail: Low
  • Tornadoes: Low

Discussion

The hot and very humid air over the Washington region (the heat index in Washington had raced up to 105 degrees at noon) will serve as fuel for storms that could develop ahead of a cold front moving into the region late today.

The National Weather Service has placed our region in its slight risk zone for severe storms, which is level 2 on its 0-5 scale for communicating the storm threat (with 5 being the highest risk).


(National Weather Service Storm Prediction Center)

Not everyone will necessarily see storms. For areas that are hit, some of the storms will be pretty typical of summer — with a bit of thunder and lightning and brief downpours.

But there is the chance that a few storms unleash pockets of damaging winds, or even microbursts — violent bursts of the wind thrust down to the ground that spread out and can cause tree and even structural damage.

Given the amount of moisture in the air, some of the rain could be extremely heavy. The HRRR model projects precipitable water, a measure of atmospheric moisture, to exceed two inches in some areas, which is very high. The storms should move through quickly enough to avoid widespread flash flooding, but some localized flooding of streams and urban areas, due to runoff, cannot be ruled out.


HRRR model simulation of precipitable water at 5 p.m.

Rainfall amounts are likely to vary widely depending on where the most intense storms track, but there is the potential one to two inches of rainfall in a short amount of time.


HRRR model estimated rainfall projection through 9 p.m. Friday.

As with all summer storms, lightning is a threat and should be taken seriously. Remember the saying, “When thunder roars, head indoors.”

We will update this post as storms develop.


Lightning seen from Washington on May 25. (Terri Walker via Twitter)