Cooler and drier weather will continue for inland areas this week, with high temperatures as much as 5 to 10 degrees below average through Friday. Lowest daytime relative humidity for the deserts will fall to 10 to 15 percent through Thursday. Southwest to west winds will gust 25 to 35 mph during the afternoons and early evenings through Thursday, with near critical fire weather conditions on the desert slopes of the mountains. Warmer and more humid for the Labor Day weekend. Mid and high level moisture from the tropics could interact with a trough of low pressure near the California coast, bringing a chance for showers and a slight chance of thunderstorms during the weekend.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
Generally a little cooler than at this time yesterday under sunny skies. Sfc pressure gradients are still onshore but trending weaker. The windy locations in the mtns and on desert slopes are reporting wind gusts of about 25-35 mph.
A low pressure system near the west coast will maintain onshore flow with a deeper marine layer and cooler, drier conditions through Friday. Inland high temperatures will be 5 to 10 degrees below average. High temperatures will range from the mid to upper 70s near the coast, the mid 80s to lower 90s for the Inland Empire and around 100 in the lower deserts. Night and morning low clouds will be patchy, but may extend inland into portions of the western valleys at times. Low humidity and gusty westerly winds will bring locally elevated fire weather conditions to the desert slopes during the afternoons.
Tropical Storm Marie is currently about 1,300 miles south southeast of San Diego. It is expected to move to the northwest at about 9 mph and strengthen, becoming a hurricane on Thursday before beginning to weaken late Saturday. By Sunday, it is expected to be about 775 miles southwest of San Diego.
The most likely scenario for southern California would be for some mid and high level moisture from Hurricane Marie to be drawn northeastward across southern California into the Great Basin by the low pressure system off the West Coast. This would bring a chance of showers and a slight chance of thunderstorms from Saturday into next Monday.
Forecast details are still uncertain but a majority of ensemble members indicate periods of (generally) light precipitation for the weekend, although brief periods of locally heavier precipitation cannot be ruled out if tstms develop.
Warmer and drier weather will likely return for next Tuesday.
011800z, Coasts/Valleys, Mostly SKC this afternoon. Low clouds based 1000-1500 ft MSL form in very patchy fashion after 04z Wed up to 15 miles inland, reaching maximum cloud coverage (~60%) around 09z before retracting back to the coast by 13z. Coverage in coastal Orange County will be even patchier with only a 25% chance for more than an hour of cigs from 07-12z.
.Mountains/Deserts, Mostly clear skies today and tonight. Breezy westerly winds mainly through mountain passes and desert slopes through 22-07Z. Gusts 25-40 kts with pockets of moderate up/downdrafts over and in lee of ridges.
No hazardous marine conditions are expected through Saturday. Wind gusts around 20 knots are expected each afternoon and evening through Thursday in the vicinity of San Clemente Island.
Southerly swells from tropical cyclones will continue this week. There is a chance of a swell capable of producing high surf arriving this weekend, however confidence on surf size and timing is rather low today. Stay tuned as details become clearer in coming days.
Ca, None. PZ, None.
