Weekend Weather Forecast in Two Words: Overcast and Humid

Southern California’s spring heat wave began to dissolve Thursday in a scattering of local showers and thunderstorms that set the stage for a weekend that forecasters said will be overcast and humid everywhere, except in the deserts, where it will be sunny and humid.

Spawned by a mass of moist and unstable air from northern Mexico, showers spread from the coastline to the deserts and were expected to continue today, to the accompaniment of occasional lightning strikes and short-lived but respectable southeast winds gusting at times to 25 m.p.h. and above.

“What will happen next depends pretty much on an upper-level area of high pressure that is presently locked over Idaho and northern Nevada,” said Cary Schudy, meteorologist-spokesman for Earth Environment Service, a private forecasting firm based in San Francisco. “At present, it looks like that high might move away to the south. If that happens, the showers will end and Southern California should get warmer over the weekend. But we can’t yet be sure when or if the high is going to move.”

Forecasters agreed that today will be very much like Thursday in most areas, with high humidity expected to be a feature of the weekend, whether it remains partly overcast and cooler or returns to the clear and sunny skies of midweek.

High temperature in Orange Count Thursday was 75 degrees in Santa Ana. It was 71 in San Juan Capistrano 71 and 66 in Newport Beach. The National Weather Service predicted that today would be about the same or slightly warmer along and inland.

Night and morning low clouds were expected to hang over the coastline most mornings, with thundershowers possible at scattered points today and a high in the low 70s along the beaches--which would make the air about eight degrees warmer than the ocean, where surf is expected to run three to five feet today, diminishing to two or three feet Saturday and Sunday.

Mountain temperatures were forecast to reach the lower 80s at resort levels Saturday and Sunday, with southeast winds to 25 m.p.h. today, diminishing to occasional gusts in the 20-m.p.h. range by Saturday.

Northern deserts were expecting afternoon temperatures in the upper 90s, with southern desert readings generally eight to 10 degrees warmer.