In gloomy June, gray skies meant clouds, but not rain

July 01, 1995|By Frank D. Roylance | Frank D. Roylance,Sun Staff Writer

June and gloom. They're starting to sound like they go together.

The month that ended yesterday delivered twice as many cloudy days -- and only half as many sunny or partly cloudy days -- as a normal June in Baltimore.

In fact, there have been nothing but gray skies at Baltimore-Washington International Airport since June 19, said National Weather Service forecaster Amet Figueroa.

"It's been very unusual," he said, particularly in the last 11 days. Even in December, normally Baltimore's grayest month, 11 straight days of cloudy skies would be "a pretty good stretch."

OK. But at least the clouds brought needed rain. Right?

Wrong.

At BWI, the gray skies in June had delivered only 1.78 inches of rain by late yesterday. That's well short of the normal 3.67 inches, and too little to stem a growing shortage of precipitation in the region.

The airport is 6 inches short of the 20 inches of rain normal by June 30. Average annual precipitation at BWI is 41.84 inches.

The only boon in June was that the clouds blown in from the Atlantic Ocean by persistent easterly winds since last week ended four straight days (June 18-21) of air pollution alerts. The warnings were triggered by unhealthful levels of ground-level ozone, which is formed by auto exhaust and sunshine.

"The pollution problem has been alleviated," Mr. Figueroa said.

Forecasters at BWI measure cloudiness as part of their daytime observations.

If a day's observations rate the sky less than four-tenths obscured by clouds on average, it's recorded as a "clear" day. If it's four-tenths to seven-tenths obscured, it's partly cloudy. And if clouds cover eight-tenths of the sky or more, it's a government-certified cloudy day.

DTC In June, six clear and three partly-cloudy days were recorded at the airport, or nine days with appreciable sunshine, less than half the 19.6 days of a "normal" June.

Twenty-one days were cloudy, more than twice the 10.3-day average. December only averages 15.6 cloudy days, Mr. Figueroa said. Only once was a clear day followed by at least one more -- June 16-19.

But the clouds of June didn't translate into lower temperatures.

The persistent cloud cover acted as a kind of thermal blanket, Mr. Figueroa said, keeping nighttime temperatures from falling to normal lows. Daytime temperatures were close to normal, so the month ended with average temperatures about two degrees above normal.

Mr. Figueroa blamed an unusual northerly bend in the jet stream for June's fade to gray. When it veers into Canada, "systems in this area have nothing to push them away."

As a result, a low-pressure system off the South Carolina-Georgia coast has persisted, pumping clouds and moisture across the mid-Atlantic. In Virginia and West Virginia, the air has been unloading its moisture, causing severe flooding.

The forecast through Tuesday calls for more sun, but with continuing showers. Mr. Figueroa said the clouds will depart "very gradually."

"We're not expecting a new air mass with deep blue skies," he said. "It'll be a hazy blue, with the humidity."

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