Showers, Thunderstorms Dissolve Heat Wave

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.

Can’t Be Sure

“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 at Los Angeles Civic Center Thursday reached 85 degrees, with relative humidity splashing around from 87% in the early morning to 44% in the afternoon. The National Weather Service predicted that today would be about five degrees cooler.

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.