Thundershowers Hit in Three States

Sudden and intense thundershowers pelted the deserts and mountains of Southern California, Arizona and Nevada on Monday in the wake of an invasion of moist, unstable air from Mexico.

By mid-afternoon rain, lightning and winds gusting to 30 m.p.h. at times were reported from Winkelman, Ariz., where .73 of an inch of rain fell in just 30 minutes, to Mt. Laguna in San Diego County, which received 1.65 inches.

Palomar Mountain reported .75 of an inch by late afternoon, while the mountain community of Julian received .65, and Borrego, in the desert, had .41.

Flash-flood watches were in effect for Los Angeles, San Bernardino, Riverside, San Diego, Kern, Inyo and Imperial counties and for the western parts of Nevada and Arizona. No flash flood watch was called for Orange County, however, said National Weather Service specialist Frankie Shaw, and the two stations in the county that normally report measurable rain, El Toro and Santa Ana, were not in the path of the unstable air and did not receive any moisture.

The National Weather Service said the watches would probably remain in force overnight, although most of the violence was expected to dissipate before dawn today.

Meteorologists blamed the bad weather on the sudden development of a weak low-pressure area over Southern California, which invited an influx of marine air flowing out of a high-pressure ridge centered about 400 miles west of Seattle and extending north and south across the eastern Pacific.

Forecasters said the general instability could last through today, with high and low clouds, a few coastal showers and occasional thunderstorms--accompanied by brief but intense winds--gradually easing away to sunny skies by Wednesday.

High temperature at Los Angeles Civic Center Monday was 79 degrees, with relative humidity ranging from 54% to 90%.

In Santa Ana, the high Monday was 76 degrees, with relative humidity ranging from 62% to 80%. Today was expected to be two or three degrees warmer, but no drier, with temperatures returning to the mid-80s by Wednesday.