At exactly 10:15 this morning, NOAA Weather Radios in schools across the state emitted three long warbles and a long musical tone. They were test signals, but similar enough to those designed to warn listeners of a weather emergency in their locations.

Thankfully, there was no real emergency. This was the start of the first-ever Statewide Tornado Drill. Participating schools, businesses and households were directed to activate their emergency plans, rehearsing and discussing how they would react to a real tornado warning.

"As a general rule, the most important thing to remember is to head to the lowest small interior room where you are - away from windows," according to the Web site for the National Weather Service's Baltimore-Washington Forecast Office, in Sterling, Va.

Maryland is not exactly in Tornado Alley. But we are no strangers to the violent twisters. Ninety tornadoes were recorded in Maryland during the past 10 years. The largest number were spotted in Frederick County (28), followed (in the Baltimore area) by Baltimore (19), Arundel (17) and Harford (16) counties, according to Joe Miketta, of the NWS forecast office in Mt. Holly, N.J., who spoke Wednesday at a Severe Storms Awareness Conference near Baltimore.

The worst tornadoes in recent years have included the F-4 La Plata twister (photo, above) that struck in Charles and Calvert counties in April 2002. It killed three people in its path and injured 122. Before it dissipated over the Eastern Shore, it had carved a 64-mile path (horizontal trail in NASA photo at right) through towns, woods and fields, destroyed 344 homes and businesses and caused $100 million in damage.

Another tornado, an F-3 in September 2001 -  two weeks after 9/11 - struck College Park and portions of Howard County. It killed two Maryland students and injured 60 other people. Damages totalled $100 million. 

Smaller tornadoes are more common in the state, but they can cause considerable damage to property and threaten people in their paths. 

If you don't have a NOAA Weather Radio, buy one. They're cheap and they can wake you up and save your life when severe weather threatens. Have a severe-weather plan. Figure out the safest place to be in your home if a Tornado Warning is issued. And have sufficient food, water, batteries and other supplies on hand to shelter in place without electrical power for several days.

With any luck, you'll never need any of it. But you will sleep better.

(PHOTOS: Top: Baltimore Sun file; Middle: SUN PHOTO/Karl Merton Ferron; Bottom: NASA satellite image)