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Heavy storms dump 1 to 2 inches of rain, spawn possible tornado in Va.; more to come?

Pedestrians navigate standing water on 14th Street NW in Washington on May 5. Early-morning downpours caused localized flooding and prompted a flood warning from the National Weather Service. (Robert Miller/The Washington Post)

The powerful storm system plowing through the Eastern United States unleashed a torrent over the D.C. area, with widespread rainfall totals of one to two inches, and locally higher amounts.

A few severe thunderstorms erupted, with several damaging wind reports in the region. A possible tornado may have spun up in Virginia’s Northern Neck, flipping over cars at a Navy facility.

While the storm system has produced most of the rain that will fall in this region, there is still a small chance for some isolated thunderstorms late this afternoon and early this evening, which could be severe — including the threat of damaging gusts and an isolated tornado.

Storm rainfall

Pretty much everyone in the metro area picked up at least one inch, with amounts around 1.5 inches most common.

Here are totals through midday at the three airports:

  • Reagan National Airport: 1.61 inches
  • Dulles International Airport: 1.30 inches
  • Baltimore-Washington International Marshall Airport: 1.54 inches

At National Airport, today marks the second wettest day of the year so far.

The rains caused local street flooding because of runoff and overflowing streams. Below are a couple of videos:

By far, the heaviest amounts focused along the eastern slopes of the Blue Ridge Mountains, where three to 4.5 inches were reported and flooding occurred:

The heavy rains resulted from a conveyor belt of tropical moisture drawn northward by an area of low pressure over the Tennessee Valley.

Damaging winds and possible tornado

A few of the more intense storms sweeping through the region between 8 and 9:30 a.m. turned severe, and produced damaging wind gusts.

At the Naval Support Facility in Dahlgren, Va., in King George County, severe winds moved six cars and overturned four. Windows were also reportedly blown out. No injuries were reported from the event, a release from the Naval Support Facility said.

Adjacent to the base on the Potomac River, a buoy clocked a 70 mph wind gust.

It is very possible this was the work of a small tornado or, if not, a microburst.

The National Weather Service is sending meteorologists to the scene who will survey the damage and assess whether a tornado occurred.

In addition, there were reports of trees down from strong winds along and east of Interstate 95 in Fairfax, Prince George’s, Charles and St. Mary’s counties, as well as in the District.

Afternoon-evening storm risk

There remains the outside risk of severe weather this afternoon and evening as the storm system’s cold front has yet to pass.

The big question is whether the sun will break out this afternoon, helping fuel the atmosphere for another round of storms. Satellite imagery still shows the region socked in under cloud cover, which may limit the instability that can develop.

The National Weather Service Storm Prediction Center has removed our immediate region from its “marginal risk” zone for severe storms, although our far-western reaches are still included — as they may see more sun.

Any sun that emerges may be enough to jump-start storm development. And there is enough wind shear so that if storms do initiate, they could produce damaging winds and even an isolated tornado.

To be clear, we think the overall chance of additional storms is low and that most activity would be widely scattered to isolated and more likely toward the mountains. But we will be keeping an eye on conditions this afternoon and will post updates if needed.