An outbreak of tornadoes that hit parts of Maryland late Wednesday was among the worst to hit the region in years. While tornadoes aren’t unheard of during severe storms in the region, they aren’t usually so numerous and severe.
Here is what to know about tornadoes and the threats they can bring even outside of Tornado Alley and the Deep South, and what you can do to protect yourself.
How unusual are tornadoes in the D.C. area?
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Tornado season, explained
While tornadoes can happen at any time, spring brings the highest risk for the severe storms. April, May and June are, historically, the most active, with an average of 660 twisters a year in those months. The United States is more vulnerable to tornadoes than any other country, with an average of 1,150 to 1,200 a year.
What causes tornadoes?
The two primary ingredients are heat energy and turning winds: When warm, humid air meets wind shear, the resulting storm can sometimes twist into a tornado. Scientists say when the Gulf of Mexico is warmer than normal, it can make tornadoes worse. New research also suggests that climate change may be intensifying tornadoes at certain times of the year — as temperatures rise, more fuel is available for severe storms.
What is Tornado Alley?
Many people think that tornadoes are most common in the Great Plains, including the vertical stretch of states from Texas through Kansas and Nebraska. But your greatest risk of encountering a tornado is actually in the South — which is why some experts say the term “tornado alley” is misleading.
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Tornadoes occur annually across the region, though most of them are weak. Maryland, D.C. and Virginia combined average about two dozen twisters per year. About five to 10 per year happen within about a two-county radius of the District, but counts can vary significantly year to year.
“Tornado season” in our region is between April and September, when thunderstorms are most common. July has seen the greatest number of tornadoes by a small margin, but notable events have happened in every month of this season.
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About 85 percent of the tornadoes that strike the Washington region are weak, rating 0 or 1 on the 0-to-5 scale for intensity. About 8 to 10 percent of the tornadoes are rated 2, and 1 to 3 percent are rated 3. Only 0.2 percent of the tornadoes have been rated a 4; none has reached 5.
The most recent tornado with a rating of 3 hit College Park, Md., in September 2001. Less than a year later, La Plata, Md., was struck by a violent tornado rated a 4 in April 2002.
How likely is this to happen again?
The ingredients for Wednesday’s outbreak were largely impossible to predict before they came together. Pointing to the next such occurrence would be guesswork.
Because the peak of severe thunderstorm season is in June and July, more thunderstorms and some tornado activity are probable in the weeks ahead. The threat often persists, with less regularity, through September. A repeat of Wednesday would be an aberration, but sometimes the weather pattern that spurs a sizable event will support additional outbreaks.
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Any connection to the El Niño or La Niña climate patterns is tenuous. Still, seasons in which a La Niña event is developing, like this one, are highly represented among active tornado years in the region.
An important feature in a local stormy pattern is a boisterous jet stream dipping from Canada toward the Great Lakes, which helps draw moist, unstable air and storminess into the region. Such a weather pattern was in place Wednesday and could well return in the weeks ahead.
What should I do when a tornado threatens?
If you receive a tornado warning — whether via social media, a television news broadcast, a weather app push alert or especially through the National Weather Service’s text alert system — you should take action.
Some tornado warnings are issued when meteorologists see the hallmarks of a tornado on radar, while others are prompted by confirmed tornado sightings. Either way, a tornado could be imminent.
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The safest place to be during a tornado is in the lowest, most interior room of any sturdy building. A basem*nt is ideal, but if you don’t have one, a closet or bathtub is safest. It’s important to stay away from windows, which tornado debris can easily shatter.
If you live in an apartment on a high floor, be sure to know in advance if there is a safe and accessible place to shelter in the building’s basem*nt or on lower floors.
Given that the D.C. area is not equipped with tornado sirens, like those in the Midwest and the Southeast, it’s also key to ensure you have a way to get tornado warnings well before a storm strikes.
The Weather Service sends text alerts to any cellphone in the path of a tornado warning or other severe weather warning. If you don’t have one handy, or at all, meteorologists recommend having an inexpensive weather radio turned on anytime severe weather is in the forecast.
Do people’s insurance policies in this area cover damage from tornadoes?
Coverage for damage caused by tornadoes or other severe winds is standard in most homeowners insurance policies. That means they typically cover any damage to residential structures themselves as well as to their contents.
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That includes if a tornado causes a tree to fall on a home, for example.
Policies can vary when it comes to how any tornado damage might apply to your deductible and the amount you have to pay before insurance coverage kicks in. The Maryland Insurance Administration recommends reading your insurance policy or asking your agent or broker whether you have a single deductible for all types of losses or whether there are separate deductibles for different types of losses.
Some policies can exclude wind damage and require extra coverage for tornadoes, but such policies are more common in states that are especially prone to windstorms and hurricanes.
Most policies also include coverage for debris removal or for living expenses if a home becomes uninhabitable, so long as those losses were caused by a tornado and the policy covers wind damage.
