‘June Gloom’ Casts Pall on Summer : Weather: Drift of jet stream to the south is blamed for lingering low clouds that usually are gone by July. The same pattern is pushing storms into the Midwest.

Thanks to the persistent low clouds that have blanketed Southern California for most of the past few weeks, 1993 might be remembered as the year that summer almost didn’t happen.

According to meteorologists, a weather pattern traditionally associated with June--the fabled “June Gloom”--has lingered through July, often shrouding the sun until the afternoon and resulting in average high temperatures that are 10 degrees below normal.

“What’s going on is usually we get a lot of low clouds in June and less and less in July,” said National Weather Service forecaster Ivory Small. “This year, it just keeps on going. The low clouds just won’t go away.”

At the Civic Center, the average temperature this month has been 73 while in the San Gabriel Valley the highs have been in the low 80s. The average temperature in Long Beach has been around 71 degrees.

The unusual weather pattern is the product of a weaker than usual high-pressure system off the Northwest that is allowing the jet stream to dip south. At the same time, the usual subtropical high in the eastern Pacific is weaker than average this year, also allowing the jet stream, which normally lies in more northern latitudes, to dip southward and guide storms into the Midwest. These storms are contributing to the devastating floods in that region. As for the Southland, “The same thing is bringing low clouds in here,” Small said.

On the bright side, the dreary weather has reduced the crowds at some local beaches and public swimming pools and improved the air quality.

Weekday attendance at Huntington State Beach has declined by about 70% compared to last year, said lifeguard supervisor Finn McClafferty. The smaller crowds also mean ocean rescues have decreased by about 70%.

Likewise, attendance at Los Angeles city pools has dropped 25% this month compared to last year, said an official with the Los Angeles Department of Recreation and Parks.

The persistent marine layer has also caused a reduction in smog levels. So far this year, nine first-stage smog alerts have been recorded throughout the Los Angeles Basin, according to the South Coast Air Quality Management District. Last year at this time, there had been 17.

Normally, thermal inversions--a layer of warm air on top of cool marine air--clamp a lid 1,000 to 1,500 feet above sea level around the Los Angeles Basin, trapping the pollution. Emissions interacting with sunlight throughout the day make things worse.

This year, said Joe Cassmassi, senior meteorologist with the AQMD, instead of a high-pressure system that fosters an inversion, there has been an upper level, low-pressure system that promotes the dilution of pollutants. And the low clouds have prevented the pollutants from reacting with sunlight and causing more smog.

The cool weather may take a bite out of utility bills. The Department of Water and Power is forecasting that demand for electricity in Los Angeles will be 8% less than originally projected. Water usage is also down about 8% according to the DWP, although it is not possible to say how much of that is due to the weather or to the 20% savings resulting from drought conservation measures.

Feels Like June, Looks Like June. . . The Southland, usually baking in July, is experiencing temperatures and morning cloudiness more typical of June. Forecasters say the same phenomenon linked to the Midwest floods is changing the weather patterns here.

This Summer A weaker than usual high-pressure system off the Northwest is allowing the jet stream to dip south. The jet stream-harnessed between that high and the strong Bermuda High off the East Coast-is bringing cloudy skies to the Southland and fueling the storms in the Midwest. Last Summer A subtropical high in the Southwest prevented the jet stream from dipping south last summer, keeping the Southland sunny and hot. Sources: WeatherData Inc.; Times Staff