As Fall Arrives, Summer Hotfoots It Into Town

The summer days that never seemed to show up between July and September finally arrived--just in time for the fall, which officially began Monday.

But forecasters said their stay will be as brief as they are belated.

For the past three months, a low-pressure air mass clinging to the Southern California coast kept days cloudy and cool. But that mass finally has moved on, bringing sunnier days, forecasters said.

But normal fall weather probably will kick in within a week or two as fronts move south from Alaska, forecaster Steve Burback said. Burback is a meteorologist with WeatherData Inc., the company that provides weather information for The Times.

“It’s like you’re getting the summer, but you’re getting it in the fall and only a week’s worth of it,” Burback said.

Thermometers across Orange County on Monday recorded temperatures in or near the 90s. In Santa Ana, it reached 89, which was 4 degrees above average.

The layer of clouds and fog that parked itself off the coast four months ago put a big chill on June and July, when temperatures were 5 to 8 degrees below 1990 averages, and kept many August and September days overcast.

The layer weakened in mid-August, and now “no longer is a real factor,” Burback said. He said that translates to warmer, clearer days for the rest of the week, with highs staying in the 90s.

Unfortunately, another summer feature, the smog alert, made a return Sunday to Orange County. Joe Cassmassi, senior meteorologist at South Coast Air Quality Management District, said the Stage 1 alert, the first of the year, was partially prompted by the recent weather changes.

While at full strength, the low-pressure air mass had created strong marine breezes and a sun-blocking overcast that helped keep smog from reaching harmful concentrations. Now, however, it is easier for the smog to form a pocket over the central portion of the county.

But while the air mass’ smog-abating assistance is over, Cassmassi said at least it came at the right time. Sunny days, one of the factors that help kick up smog levels, are less harmful now than in mid-summer, because less sunlight is being directed at Southern California.

“So we don’t have as much sunlight, which means smog won’t form as regularly,” he said.

Smog levels, which reached 200 parts per million on the pollutant chart in Anaheim on Sunday, were down to 42 on Monday. Officials said the Sunday level was reached because of a variety of odd weather conditions, including weak sea breezes and a low inversion layer, a condition in which warm air traps cool air close to ground level.

Summer in September

Temperatures were about 5 degrees above normal across Orange County, according to meteoroligists. A high-pressure system has chased away clouds, letting the sun shine through.

Source: WeatherData