4:40 p.m. update: After conducting a damage survey, the National Weather Service has confirmed a tornado touched down in South Arlington, the Tidal Basin and the H Street Corridor.  It said the tornado caused “sporadic damage” on 4.5-mile track beginning near Army-Navy Country Club and ending at St. Aloysius Church at North Capitol Street and I St., which endured roof damage.

The Weather Service rated the tornado EF-0, the lowest level on its 0-5 scale for intensity. It estimated its peak winds at 60-70 mph, with a maximum width of 25-50 yards.

Original post from 11:15 a.m.

On Thursday, multiple squall-line tornadoes spun up in the D.C. area, leaving behind sheared roofs and scores of downed trees.

The National Weather Service has confirmed at least two tornadoes touched down, one in Southeast Washington and one in Herndon, Va.

We believe at least one more occurred between the Tidal Basin and the H Street Corridor in the District, and possibly several others.

In addition to the two tornadoes it has confirmed, the Weather Service is assessing damage near the Tidal Basin to determine whether a tornado, in fact, occurred. And it also said it is surveying an area of damage near Culpeper, Va.

We think there may also be evidence that a tornado touched down in the vicinity of Manassas.

The Tidal Basin to H Street Corridor tornado

Although the National Weather Service has yet to officially declare a tornado occurred in this area, we are fairly convinced.

Doppler radar revealed what is known as a velocity couplet — in which winds are blowing toward and away from the radar side by side — indicative of rotation where we think the tornado passed:

We have two videos that show discernible swirls passing over the Potomac River and Tidal Basin.

Here’s one from the National Park Service:

And a second, wider view of the vortex crossing the Potomac, sent to the Capital Weather Gang by reader Ryan Lyk, is displayed at the top of this post.

In both videos, you can see the tornado circulation disturbing the water over the Tidal Basin and Potomac River.

This tornado downed numerous cherry trees at the Tidal Basin:

Then, as it headed northeast, it lifted part of the roof off St. Aloysius Church near Gonzaga College High School and Union Station along North Capitol Street. Other nearby buildings also suffered roof damage (see photos below). Eyewitness videos also reveal rotating clouds in that vicinity:

Here are photos of the resulting damage:

South Arlington tornado?

The same storm that spawned the possible Tidal Basin-H Street Corridor tornado may have also produced a tornado in South Arlington — or just one tornado may have occurred and passed over this entire area.

Doppler radar indicated a possible small tornadic circulation in South Arlington near the Pentagon about 1:40 p.m. Thursday afternoon:

We believe we have video and photo evidence to suggest it touched down.

This video isn’t the greatest quality, but the view from Dorchester Towers, just west of the Pentagon, may show a tornado:

Below where this possible tornadic circulation passed, trees were snapped right along Interstate 395 by the Army-Navy Country Club:

Here’s another photo of damage from at the Army-Navy Country Club from reader Carrie Simmons:

Posted by Carrie Simmons on Thursday, April 6, 2017

Reader Elizabeth Twitchell reported: “South end of Crystal City, two of the light fixtures pulled down. A burst of something hit the windows and made a huge boom in our first floor office right next to these.”

Posted by Elizabeth Twitchell on Thursday, April 6, 2017

Twitchell also posted this photo of a snapped tree:

Posted by Elizabeth Twitchell on Thursday, April 6, 2017

The Joint Base Anacostia-Bolling Tornado

This tornado was confirmed by the National Weather Service. It was rated EF-0, the lowest level on the 0-to-5 scale for tornado intensity. It was 25 yards wide, packed winds of 60 to 70 mph, and carved a one-mile path at 1:41 p.m. Thursday.

This storm blew off the tops of some apartment buildings on Stanton Road in Southeast Washington:

Posted by Sue Gregory on Thursday, April 6, 2017

Herndon tornado

The National Weather Service confirmed a small tornado touched down in Herndon near the Loudoun-Fairfax County line at 1:36 p.m. It was rated EF-0, contained winds of 60 to 70 mph and was on the ground for less than a mile.

Capital Weather Gang reader Ben Tomhave said the small twister caused a good deal of roof damage and numerous downed trees in the Forest Ridge neighborhood. “I live a couple blocks from there, [and] heard a rushing, roaring sound,” he said on Twitter. He prepared a document, which contains several photos of the damage.

Manassas tornado?

The same rotating storm that passed through Herndon may have originated from Manassas, where a tornado may have also occurred. We do not, however, have video evidence of a funnel cloud or tornado on the ground.

Nevertheless, eyewitness reports and damage photos are suggestive of a possible twister.

“I was at the Bowl America in Manassas on Balls Ford Road close to [Interstate] 66,” said Capital Weather Gang reader Jean Thoensen on Facebook. “There were shingles coming off the Quality Inn motel next door and crashing into the bowling alley roof. Looked exactly like news footage of debris flying from a tornado.”

“Something hit the Manaport [Plaza] shopping center in Manassas,” added reader Chloe Ferogh, referring to a shopping center just two miles from the Bowl America. “Large sections of the roof were torn off.”

Capital Weather Gang reader Shawn Gardner reported “tons of trees down and a lot of debris thrown about” in his Manassas neighborhood.

In the nearby Dunbarton community in Bristow “siding was ripped from a house, patio tables flipped (without umbrellas attached), garden pieces swept away by wind and taken several houses down,” reader Beth Crooks said.

Below are two pictures that show damage from Manassas and Bristow:

Possible Loudoun County funnel cloud, near Ashburn

Readers submitted several videos suggestive of a funnel cloud in eastern Loudoun County, between 1:35 and 1:40 p.m. Thursday. No confirmed tornado touched down in this area, but we received several videos which shows one was at least trying to form:

From One Loudoun in Ashburn, by Hiro Kawashita:

From Loudoun County Parkway and Russell Branch Parkway:

View from Loudoun County Parkway and Russell Branch Parkway, looking southwest, tornado trying to form

Posted by Doug Smith on Thursday, April 6, 2017

From Ashburn:

Cloud rotation during tornado warning in Ashburn

Posted by Adam Roeder on Thursday, April 6, 2017

From Potomac Falls, by Andrew Morrell (caution: brief strong language):

And here are some still images…

From Ashburn:

From Sterling: