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A weak but destructive tornado traced a four-mile trail through Reston just before 9pm. Friday night, leaving behind trees felled, a crushed vehicle and a townhouse to condemn.
The National Weather Service examined the damage caused by the tornado on Saturday and estimated the maximum winds of the tornado at 70 mph. While these winds were strong enough to uproot and cut down trees, the twisting is ranked at the low end for the intensity of the tornado.
Tornadoes are listed from 0 to 5 The improved Fujita (EF) scale and weather service ranked EF-0 in the storm of Friday night.
In its storm report, the weather service reported that the tornado damage was "discontinuous" along its four-mile course. In some areas trees have been knocked down, while others have been left intact.
The weather service noted damage to "isolated" trees near the US Geological Survey Complex and just north of Reston Hospital. After passing the story of Trader Joe's grocery store and destroying an outdoor shed, the storm shot down a large tree two feet in diameter that "crashed on the top floor of a townhouse on the Quietree walk, "which led the authorities to condemn the property. Service report said.
A tree was damaged in a townhouse on the quiet street in Reston, Virginia after a tornado on Friday night. (John Keady)
The storm cut down several other large trees in Reston neighborhoods, including a 100-foot-high that crushed an unoccupied vehicle along Center Harbor Road near Reston Parkway.
Police and firefighters said no injuries had been reported, but the storm had caused many disturbances.
"Our officers responded to a ton of roadblocks," which means the streets are filled with tree branches, power lines and other debris, Sgt said. James Curry, a spokesman for the police. He stated that there had been "two close calls" in which falling debris had nearly run out of vehicles and parked houses, but the material damage was not generalized. .
The tornado was short lived and evolved quickly. It lasted only five minutes as it ran north-northeast at 50 mph.
How did it go?
Around 8:30 pm On Friday, the grain line that approached the cold front of the largest storm was deformed into "S" in northern Virginia. Part of this "S" began to tilt northward in an arc of intense storms, crossing Manassas and Centerville. This storm arc is shown in the radar image below, at 20:47.
Radar View of Storms at 3:47 pm The left panel shows the intensity of precipitation that examines the shape of the arc or arc. The right panel is an estimate of the wind speed. (Radarscope)
The bursts along the bow were significant (green colors in the right panel of the figure above), but contained a small pocket of extreme gusts, reaching almost 90 mph (blue colors) not far from the ground. This possible subsidence was east of Centerville and south of Chantilly, and lasted only a few minutes and a few kilometers. Downburst gusts are often contained in arc echoes and are usually located near the top of the arc.
A few minutes later, as he climbed rapidly to the north, the bow echo began to dissociate. What appeared around 9 pm was a transient supercell or a rotating storm, shown in the figure below, which zoomed in on the Reston area. The south end of the supercell contained a hook-shaped appendage encompassing Reston.
Radar showing a tornado storm near Reston just before 9pm. Friday night. The left panel shows rainfall intensity and a hook-shaped pattern near Reston, sometimes indicative of a tornado. The right panel shows a velocity couplet near Reston with winds blowing from the radar (in red) and to the radar (in green), which often indicates a tornado. (Radarscope)
The Doppler radar winds revealed a counterclockwise circulation (mesocyclone) in the hook and on Reston – as indicated by the nearby red and green colors. The red colors are winds away from the Doppler, the green indicates that the wind is blowing towards the radar. Together, they perform a counterclockwise circulation very close to the ground. The Reston tornado has developed within this mesocyclone.
The rapidly increasing south winds with the altitude Friday night, called wind shear, created a rotation in the atmosphere: giant and invisible horizontal wind "rolls". Drafts in the convective clouds bent portions of these rollers vertically, thus changing the axis of rotation from horizontal to vertical. This is one of the ways that the mesocyclone could have formed.
pics
Paul Duggan of the Washington Post contributed to this report.
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