From the ABC 7 Weather team

Strong tornadoes like to strike Virginia in September

September 6, 2011 - 01:23 PM
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September is a time of violent weather for Virginians, with deadly, hurricane-generated tornadoes historically whipping around the state.

The biggest percentage of strong tornadoes in Virginia historically occur in September and January. Here, a twister enters a mature stage of development in Enid, Okla., in 1966. (Source: NOAA's National Severe Storms Laboratory Collection)

The weather in Virginia this Labor Day weekend was smooth and warm as a bun, perfect for getting some last-minute beach time before the fall chill settles in. With nary a cloud in sight at times, it was easy to forget that September is historically one of the most active times in Virginia for huge tornadoes that rip roofs from houses and steal lives.

In fact, several major tornado outbreaks have occurred in the state right around Labor Day itself. More on that in a minute.

Why is September in the Commonwealth so violent?

Chalk it down partly to the influence of hurricanes. These massive sea storms brush by Virginia with plenty of energy to spare, which can shoot off and become tornadoes. At least fifteen hurricanes have sent funnel clouds spinning around the state since the start of the 20th century, including 1979's dastardly David, 1959's gruesome Gracie, and 1996's bodacious Bertha.

Fall cold fronts also contribute to spreading powerful tornadoes on the East Coast. Says the local National Weather Service: "Under these atmospheric conditions, stronger winds aloft tend to lead to more intense and longer lasting thunderstorms. This in turn increases the risk of a strong or deadly tornado."

There have been 71 recorded tornadoes during the steamy Virginia July from 1950 to 2000, making it the state's most active month for these treacherous gyrators. (Note that the recorded number of tornadoes may only represent one-third of the actual count thanks to poor documentation, lack of property damage or twisters touching down in unpopulated areas.) The count drops to 51 in August over the same time period and then 31 in September. However, a near majority of the state's strongest tornadoes have struck in September, with 13 (or 42 percent) of the twisters at or above EF-2 strength, which is potent enough to blow cars off the road and rip apart manmade structures. The only month with stronger tornadoes is January, when half of a grand total of 6 tornadoes exceeded EF-2 power.

Differences in topography (mountains!), humidity (the Bay!) and population density have spurred more reports of tornadoes in certain areas of the state. Northern Virginia and the land right below Virginia have had high numbers of tornadoes. Here's how the entire state has fared over the past six decades:

virginia tornadoes by county

So what about those Labor Day outbreaks?

The first known killer holiday tornadothon occurred on Sept. 5, 1935, when an unnamed hurricane swerved over the Virginia coastline and threw out several raucous twisters. The first touched down around breakfast in Ringgold, a town a few miles away from the North Carolina border, sending a family fleeing for their lives as their house collapsed in the backdrop. Another tornado then moved through Prince Edward and Cumberland counties, killing three people and plucking off the roof of Hampton Sidney College. A third and a fourth hit Southampton County and Norfolk; here's what an observer in the American Meteorological Society Bulletin had to say:

A tornado near Norfolk, Va., began by destroying trees and sheds on a point of land. The twister then crossed a creek, sending up the water so that the creek bottom was plainly visible and gouged out the exposed mud, carried anchored small boats onto the shore, ripped off part of a heavy pier, and destroyed some buildings. It became a waterspout in Hampton Roads, but changed back to a tornado and dumped a railroad gondola car and some refrigerator cars off the tracks in a railroad yard; then sucked up another creek, damaged some airplane hangers; and finally headed up the Chesapeake Bay as a waterspout.

Long after the crabs stopped raining down in the Bay, another tornado outbreak burst out of Virginia on Sept. 5, 1979. Hurricane David was the prime mover behind the severe weather, which added up to 34 tornadoes along the East Coast. Eight of those hit in Virginia, killing one person in Fairfax and racking up about $6 million in damage. These were weird beasts, crawling in an unexpected way. Says the weather service:

Because the tornadoes were associated with the spiral bands of a hurricane, they moved from the southeast to the northwest, unlike most tornadoes which move from southwest to northeast. Seven more tornadoes set down in Maryland.

So don't get too comfy with the recent nice weather, at least not until the end of the Atlantic hurricane season. That's all the way ahead on Nov. 30. (Follow this link for more September tornado records in Virginia.)

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