The tornado that damaged a high school in Northern Virginia Tuesday only appeared on radar for a few minutes before touching down, forecasters say.
The weak twister hit during a powerful pre-dawn storm, the National Weather Service has confirmed. It formed because the storm, fueled by a fire hose of tropical moisture, got strong enough and tall enough in the atmosphere to create a spinning motion.
The system was tracked for about 5 or 6 minutes, just across the Beltway toward Lincolnia, said Chris Strong a National Weather Service meteorologist in its Sterling office.
Strong was watching radar when the storm formed, he said. The NWS sent an alert at 5:53 a.m. that "a severe thunderstorm capable of producing a tornado was located over Lincolnia, or over Annandale, moving north at 15 mph."
Just a minute later, the EF0 tornado would touch down at the school.
The twister is the first in the D.C. Metro area since another EF0 touched down last August in Fauquier County.
The last tornado inside the Beltway was in April 2017, when a pair of EF0 tornadoes crossed the Potomac from Arlington into DC.
An EF0 tornado is the weakest tornado on the Enhanced Fujita scale, a system that estimates tornado wind speeds based on damage left behind.
The area’s strongest tornado touched down in La Plata, Maryland on April 28, 2002. The storm powerful enough to strip the bark from trees. Five people died and hundreds of homes and businesses were destroyed.
Tuesday’s tornado had an estimated maximum wind speed of 70 mph and a maximum path width of 100 yards, the NWS said. Its path was a quarter-mile long.
Strong said that weak tornadoes like these pop up in the D.C. area somewhat frequently.
So far this month has been pretty tame when it comes to tornado formation, he said. “But we can and do get tornadoes at any time.”
“Tornadoes are like snowfall here,” he said, adding that some years there are a lot and some years there are none.
Rain has soaked the D.C. area since Saturday, with some spots getting 10-12 inches of rain in seven days, and more is expected Wednesday. Storm Team4 says the region could see another inch of rain. A flash flood watch remains in effect.