Record-Breaking Heat Dries Out Southland : Weather: Downtown hits 88 after high-pressure ‘door,’ which had opened to let in storms, closes firmly. High temperatures are expected to continue through the weekend.

It was 88 degrees at the Los Angeles Civic Center on Wednesday--2 degrees above the old record for Feb. 1--and forecasters said it should be just as hot today and Friday.

Experts said it is all because of that meteorological door you might have heard about during the flooding last month.

In relatively dry years, the door--a massive high-pressure system that lurks over the Southwest--remains shut, blocking the eastward movement of Pacific storms and diverting them north into Oregon, Washington and British Columbia, according to Curtis Brack, a meteorologist with WeatherData Inc., which provides forecasts for The Times.

But last month, because of changes in weather patterns that have yet to be fully explained, the door swung open, with the high-pressure system weakening and retreating to the east. The Pacific storms moved onshore unimpeded during January, bringing the torrential cloudbursts that caused devastating flooding in Northern and Southern California.

Now, in February, the door has slammed shut again, blocking the cool, wet weather from the ocean with a massive high-pressure system rebuilding over Nevada.

Brack said the heat has been generated by a mild Santa Ana condition. Winds circulating clockwise around the high pressure are warmed and dried by compression as they sweep down the slopes of the coastal mountains and into the Los Angeles area.

No one was happier about the unseasonably warm weather than Cass Golnaraghi, who watched the number of customers at his Reseda carwash increase from zero last week to 400 on Wednesday.

“We hadn’t had any business in a month,” Golnaraghi said, as he watched mud-encrusted cars line up to shower off.

Golnaraghi said it was hard to believe that it had been only a few days since half of his workers were forced to sit around, hoping that the rain would stop while the others did not even bother to show up.

“Everybody’s working now. They’re making money, I’m making money,” he said. “A very good day, a very good day.”

Wednesday’s top reading of 88 in Los Angeles broke a record that stood for 41 years. Monrovia, with 92 degrees, was the hottest spot in the 48 contiguous states for the second straight day.

Brack said the heat wave should continue until the weekend, with a Downtown high today of 89 and another 88-degree reading Friday.

He said it will be even hotter in the San Fernando and San Gabriel valleys, with highs both days near or above 90.

“Then the high-pressure ridge will start weakening a little,” Brack said. “Temperatures will drop into the low 80s over the weekend, and by Sunday, a low-pressure (storm) system will start moving in, with rain as far south as San Francisco.”

The door will open a crack, but it won’t swing all the way open, the forecaster said.

“There won’t be any rain in Southern California,” he said.