Average annual number of tornadoes per 10,000 square miles from 1991-2010 (NOAA National Climatic Data Center)

Since 1990, Maryland has averaged 9.9 tornadoes per 10,000 square miles each year, trailing only Florida’s 12.2, and Kansas’ 11.7 in the 50 states.

Link: U.S. Tornado Climatology (NOAA)

To be sure, when you take land area out of the equation and only consider the absolute number of annual tornadoes in a given state, Maryland ranks much lower. It averages just 10 tornadoes annually, in the bottom half of states. Texas, the leading state, averages 155.

But when you factor in Maryland’s diminutive size, its tornado concentration is 67 percent higher than the Lonestar state’s.

What’s the trigger for the elevated tornado density in Terp-land?

“It’s just east of the Appalachians. The air sinks down off the Appalachians and there’s a little bit of low pressure trough that sets up and trigger thunderstorms,” said Dr. Greg Forbes, the Weather Channel’s severe weather expert. “It’s also close to the Delaware Bay and Atlantic Ocean so there are some local winds the thunderstorms can tap to create tornadoes.”

Two large tornadoes have touched down in Maryland since 2000:

* The April 28, 2002 F4 tornado in La Plata

* The September 24, 2001 F3 tornado in College Park

Link: Maryland Historical Tornadoes (National Weather Service)

Virginia does not rank among the top tier states for tornado density. It averages just 4.5 tornadoes per year per 10,000 square miles, less than half the number of Maryland. On the other hand, Virginia’s average total number of annual tornadoes is 18, almost double Maryland’s (10). In 2011, Virginia had about 50 tornadoes, second most on record.

Link: Virginia Historical Tornadoes (National Weather Service)

As for the District proper, it is so small (just 68.3 square miles) that relatively few tornadoes have touched down. Weather.com reports just 9 confirmed tornadoes have occurred since 1814.

Link: D.C. Historical Tornadoes (National Weather Service)

Related posts:

Washington D.C. area’s worst five tornado events

Fairfax County, Va. prepares for tornado season