Marine Air Layer to Cool Off Southland

Skies were warm and just a bit hazy in Orange County Thursday, but the National Weather Service said a general cooling trend can be expected beginning today and lasting through most of the weekend.

The high temperature in Santa Ana was 75 degrees Thursday and 67 degrees at Newport Beach. Forecasters predicted it would be three or four degrees cooler today--with a high in the upper 60s expected Saturday.

Meteorologists blamed the change on a deepening of the marine air layer.

Southwestern breezes, they explained, brought warm and moist air--with quite a bit of night and morning cloudiness--to the Southland Wednesday and Thursday, while the change in the marine layer can be expected to make the low clouds and fog stay around even longer today and Saturday.

High clouds will be sweeping across the sky this afternoon--and the low clouds and fog can be expected to re-form as soon as the sun goes down.

Beaches should be fine by early afternoon, though; the weather service predicted surf rising to three feet or so on most beaches, with a west to northwest wind to 18 m.p.h. at times and water temperature in the low 60s--only a degree or two cooler than the air.

Weekend seafarers were told to expect 8 to 15 knots of southwesterly wind, with west and southwest swell to two feet during the afternoon in the inshore waters between Point Conception and the Mexican border, while those who venture farther out should find the wind 10 to 20 knots northwest and combined seas running to 10 feet during the late afternoon and evening.

Mountain visitors will find the winds gusting south to southwest at 15 to 25 m.p.h. this afternoon, the weather service said. Winds should increase on Saturday with partly cloudy skies, a chance of showers and resort level temperatures ranging from the mid-40s in mid-afternoon to the 20s overnight.

In the Sierra, where the snow level was pegged at about 7,000 feet, a chance of showers was in the forecast for Saturday with winds gusting to 35 m.p.h. at times and a temperature range from the low 40s to about 15 degrees.

Southwest winds to 30 m.p.h. were predicted for the high and low desert, with plenty of high cloudiness and a slight chance of showers in the Owens Valley. The cooling trend was expected to carry through most of the weekend, with the high desert in the 70s and low desert in the 80s.

Arizona’s weekend was expected to begin cloudy with a few showers in the northwest and wind rising to 20 m.p.h. at times over the deserts and mountains. But the weather service said fair skies should return by Sunday with afternoon highs to the lower 60s in the mountains and to the mid-80s in the desert.

Las Vegas’ skies were expected to be fair and dry with highs in the upper 60s.

San Francisco’s weekend forecast is pretty much typical for this time of year: Low clouds and fog in the morning turning sunny inland by early afternoon with variable winds to 15 m.p.h. and temperatures ranging from the mid-60s to the low 70s . . . and, of course, about a 30% chance of rain during the period.