From the ABC 7 Weather team

Red flag warning in D.C.: firefighters explain what it means

February 14, 2011 - 01:33 PM
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The whole region is now under a red-flag warning, almost all the way up to Baltimore. What’s that mean?

Different things to different people. A red flag is basically a heads-up to emergency and forestry departments – as well as any citizen planning on burning stuff outside – that conditions are ripe for "explosive fire growth potential." Individual states set their own criteria for raising this kind of alarm. In Virginia, it takes three things: a relative humidity of less than 30 percent, sustained winds of 20 m.p.h. or greater and a fuel moisture average of 8 percent or less. That last measure describes how wet the ground and shrubbery are over the course of 10 hours.

For suburbs with a lot of plant matter scattered about, a red-flag day might cause a fire department to beef up its resources or staff. Today in Fauquier County, for instance, fire officials are sending additional units out when responding to calls for outdoors fires.

“We double the complement on those types of fires right off the bat,” says Darren Stevens, assistant chief of the county’s fire and rescue agency. “The dry brush really promotes a quick spread of fire, and the wind makes it harder to contain.”

But what about more urban areas, where the threat of forest fires doesn’t carry as much weight?

These extremely windy, dry days can still be a hassle for various reasons. Take a look at the handy fire triangle: Days like today ratchet up the oxygen and fuel components needed for a big blaze. And the way our city’s blocks are structured the results can be devastating.

“Lot of residential areas, and row houses in particular, have wooden porches in the rear along the alleys,” says Pete Piringer, D.C. fire and emergency department spokesman. “The wind a lot of times can intensify a fire really quickly and spread it” along these wooden platforms so that it eats up several houses at a time.

Other problems: “When you have 20, 30 or 40 m.p.h. winds, your hose stream might not be as effective when you’re outdoors,” says Piringer. To prevent the need for the fire department to test its hose streams today, Piringer recommends not throwing your spent cigarettes into bushes or mulch piles. “The butts can get down in that mulch and smolder a while, then with the wind and drier humidity all of a sudden a fire can break out.”

So how common are red-flag warnings for our region? Stevens says Fauquier County might see five a year, usually in the early spring and early fall. The local branch of the National Weather Service says we get them every year, usually in the fire season of spring.

“It’s really dry, and there’s a lot to burn out there before the greenery comes in,” says Jared Klein, an NWS meteorologist. “We can get red flag warnings anywhere, though. The only reason there’s not one for northern Maryland is because there’s still snow cover there.”

So far it's been a quiet day from the fire outbreak perspectives. Here's hoping it stays that way.

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