A weak low pressure system moving quickly inland through southern California tonight will bring stronger onshore flow through Wednesday. This will spread cooling inland, bring stronger and gusty southwest to west winds to the mountains and deserts with the stronger gusts to 40 to 50 mph, and bring a chance of showers for late today into Wednesday with the chance for rainfall greatest in the mountains at 40 to 50 percent. Lower-level flow will go briefly offshore on Friday with drying and gusty north to northeast winds along and below the coastal slopes of the mountains gusting to 25 to 35 mph. This will be followed by warming through next weekend with high temperatures warming to 10 to 15 degrees above average for next Sunday.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
(today through Thursday), A weak low pressure system will move quickly inland through southern California tonight with a stronger low pressure system moving inland into the the Pacific Northwest on Wednesday and through the Great Basin on Thursday followed by weak lower-level offshore flow across southern California on Friday.
Onshore flow will be stronger across southern California through Thursday. There will be periods of gusty west winds for the mountains and deserts with the stronger winds for Wednesday afternoon and evening with gusts to 40 to 50 mph along the desert slopes of the mountains.
Cooling will spread inland through Wednesday with Wednesday high temperatures a few degrees below average, ranging from the mid to upper 60s near the coast to the lower to mid 70s for the Inland Empire with the lower deserts in the 80s with not much change for Thursday.
This low pressure system will also bring a chance of showers for late today into Wednesday with the greatest chances for measurable rainfall in the mountains at 40 to 50 percent. There could be around one-tenth inch of rainfall in the mountains with little or no measurable rainfall near the coast. A snow level around 8500 feet will lower to 7000 to 7500 feet for Wednesday morning.
(Friday through Monday), There will be a period of brief offshore lower-level flow on Friday with north to northeast winds gusting to 25 to 35 mph along and below the coastal slopes of the mountains. High temperatures will begin to warm on Friday with warming continuing into Sunday and possibly Monday. High temperatures on Sunday will be around 10 to 15 degrees above average ranging from the 70s near the coast to mid 80s to lower 90s for the Inland Empire with the lower deserts in the 90s. For next Monday, weak onshore flow may begin to spread cooling into the coast and valleys with deserts warming another few degrees.
310400z, Low clouds 1500-2000 ft MSL are slowly covering the lowlands of SD and Orange Counties, developing into the Inland Empire 06-10z, increasing in coverage throughout the night. VIS 0- 5SM where terrain and clouds meet in the foothills. Cloud bases gradually increase overnight, reaching 2000-3000 ft MSL by 16z throughout the coastal basin with patchy -DZ possible at the coast.
Low clouds may scatter at times after 19z but remain SCT-OVC most of the day, with mid-level BKN-OVC clouds at 7-10kft MSL above across the region. Chance (15-25%) for spotty -RA across the coastal basin after 18z, locally higher chances in the western foothills/mountains. Bases fill in coverage after 01z Wed across the coastal basin, 1500-2500 ft MSL.
Otherwise, VFR conditions prevail for most of the region.
No hazardous marine conditions expected through Wednesday. Northwest winds increase Thursday to near 20 kts.
Ca, Wind Advisory from 8 PM this evening to 11 PM PDT Wednesday for Apple and Lucerne Valleys-Coachella Valley-Riverside County Mountains-San Bernardino County Mountains-San Diego County Deserts-San Diego County Mountains-San Gorgonio Pass near Banning.
PZ, None.
