4 days of 90-degree heat at BWI isn't just gross

it also ties a record

Spell of identical daytime highs has been recorded only 12 times


News from around the Baltimore region

July 22, 2005|By Frank D. Roylance | Frank D. Roylance,SUN STAFF

You might have missed it yesterday, amid the hum of fans and air conditioners.

But yesterday's high temperature of 92 degrees at Baltimore-Washington International Airport ended a remarkable little streak of four straight days with identical daytime highs of 90.

So maybe only weather geeks care. But the last time the airport has seen such a phenomenon was nearly eight years ago - an 83-degree stretch that ended Aug. 7, 1997.

You can look it up. Steve Listemaa, of the National Weather Service's Sterling, Va. forecast office, found that four-day streaks have happened only 12 times since official record-keeping in Baltimore began in 1871. There has never been one longer.

"There seems to be a slight preference here for this phenomenon to occur during the warm summer months," said Steven M. Zubrick, science and operations officer at Sterling.

The overnight lows from July 17 through July 20 were stuck in a narrow range, too - from 73 to 75 degrees.

Blame a stubborn tropical air mass that has been stuck over the region, said forecaster Andy Woodcock.

"It's very typical for the second half of July," he said. There's so much incoming solar radiation throughout the Northern Hemisphere that there are no big temperature or pressure differences - "nothing to come down and kick the tropical air out."

There's also a certain amount of randomness, "shooting the dice," in any string of identical temperatures, Woodcock said. "It could just as easily have been 88 one day and 91 the next."

Zubrick said the streaks do seem to favor the summer months. Seven of the 12 have occurred between June 17 and Sept. 10. The hottest was a string of 95-degree days in June 1945. The coldest was 32 degrees in December 1966.

This most recent string was only the third in nearly 36 years. It also was the second-hottest of the bunch.

BWI has now seen 14 days in the 90s this summer, including eight this month; none were higher than 92. In 2002, the airport recorded 48 days in the 90s or higher.

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