Really, August, we like your cool Temperatures all summer long have been nicely below normal

August 13, 1992|By Douglas Birch | Douglas Birch,Staff Writer Staff writer Michael Ollove contributed to this article.

It's already mid-August, but some air conditioners are languishing in closets, people are snoring under sheets and temperatures today are expected to hover like blissful cherubs in the low- to mid-70s.

If forecasters are right, this could be the coolest summer in the past five years.

Fred Davis, a meteorologist with the National Weather Service atBaltimore-Washington International Airport, said that temperatures for May, June and July were 1 1/2 degrees below average.

They were 3 degrees below average for the first 11 days of August. And the long-term forecast predicts more of the same.

It may seem even cooler than it is, Mr. Davis added, because the past couple of summers were so pitiless -- with 1991 the hottest ever recorded at the Custom House in downtown Baltimore. "It's the contrast as much as it is the below-normal conditions," Mr. Davis said.

Need further proof this is a kinder, gentler season?

* Exhibit A: In the blistering summer of 1988, the temperature reached 100 degrees or above 13 times in the city and seven times in the suburbs. In 1991 the thermometer rose above 100 degrees six days in the city and two in the suburbs.

So far this summer, city residents had to put up with

triple-digitheat only one day: a record-breaking 102 on July 14.

* Exhibit B: Electricity demand is down about 1.2 percent this summer over forecasts, said John Metzger, a spokesman for Baltimore Gas and Electric Co.

"The reason for this is mainly in the decreased use of air conditioning," he said.

* Exhibit C: Clothes have generally come off without peeling.

James Wagner, senior forecaster for the National Weather Service's Climate Analysis Center in Camp Springs, said Baltimore is not alone.

The Great Plains, Mississippi valley, Great Lakes area, New York and New England are all cooler than normal, Mr. Wagner said, adding that parts of the Midwest are from 6 degrees to 9 degrees lower than average.

The cause of this outburst of moderate weather, Mr. Wagner said, can be traced to a Philippine volcano, the ice sheet over the Hudson Bay, abundant rains in many areas and the high-altitude jet stream.

The eruption of Mount Pinatubo, on June 16, 1991, belched a huge cloud of sulfur dioxide into the stratosphere, where the cloud reacted with water vapor and changed into fine droplets of sulfuric acid.

Studies estimate that this cloud, which is still circling the globe, is blocking 20 percent to 30 percent of the sun's direct radiation. By May,the droplets had caused average temperatures in the Northern Hemisphere to fall 1 1/2 degrees.

Mr. Wagner said that while the volcano helped hold down temperatures locally, it did not trigger them.

"The pattern we've been having would favor a cool summer, anyway, with or without Pinatubo," he said.

One reason, he said, is the persistence of ice floes in Hudson Bay, Canada. The floes have not yet broken up, even though in most years they are gone by the third week in July, he said.

To some extent, the floes are an effect of the cool weather, he said. But they are also a cause.

"Any air coming off that will be very cold," he said.

Most areas of the East also have been drenched with rain -- although rainfall in Maryland is so far about 4 inches below normal, he said.

"When the ground is wet like that, it's very hard for it to heat up," Mr. Wagner said, noting most of the energy of the sunlight hitting the ground goes to evaporate the water. Generally, the hotter or colder the ground, the hotter or colder the air.

Finally, he said, "the jet stream is stronger than normal and south of its normal position." As a result, the high-altitude wind, which curves west to east across North America, is drawing lots of cool air from Canada.

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