A low pressure system developing off the California coast will move toward the southeast and inland across northern Baja on Friday night. This will bring deepening of the marine layer and spread cooling inland through Friday. There is a chance of showers for Thursday and Friday, possibly continuing into Saturday. Sunday through Tuesday will be drier and gradually warmer with periods of weak offshore flow.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
(today through Friday), A closed low pressure system is developing off the California coast. This low pressure system will move toward the southeast and move inland across northern Baja late Friday and Friday night. Mid and high clouds are spreading northeastward across the area early this morning. The marine layer is slowly deepening with low clouds and fog over the coastal waters spreading inland into the far western valleys. Lowest visibilities in fog have been near higher coastal terrain into the far western valleys. A Dense Fog Advisory remains in effect for those areas until 9 AM this morning. The marine layer will continue deepening into Thursday and Friday to around 3000 feet on Thursday and 5500 to 6000 feet on Friday.
Showers could spread southward across portions of southward across portions of southwestern California on Thursday with chances for showers continuing through Friday and possibly into Saturday. Rainfall could range from one-tenth to one-quarter inch near the coast to one-quarter to one-half inch for the mountains. Chances for one-half inch or more of rainfall for Thursday through Friday ranges from 5 to 10 percent near the coast to 20 to 30 percent in the mountains. Snow levels will be around 6500 to 7000 feet.
High temperatures will cool through Friday with high temperatures on Friday mostly in the lower to mid 60s for the coast and valleys and in the lower 70s for the lower deserts.
(Saturday through Tuesday), Decreasing showers could linger into Saturday. For Sunday through Tuesday, there will be significant lower level drying with periods of mostly weak offshore flow. High temperatures will slowly warm with Tuesday high temperatures ranging from the mid to upper 60s near the coast to the lower to mid 70s for the valleys with the lower deserts also in the lower to mid 70s. That is around average for the deserts and a few to around 5 degrees above average for the coast and valleys.
211030z, Coast/Valleys, Low clouds and fog based 400-1000 feet MSL reducing vis 0-5SM will continue this morning. Scatter out expected 16-18Z, but patchy and intermittent low clouds to persist along the coast through the afternoon. Low clouds will push ashore after 23Z and move into valleys overnight into Thursday. Bases will be 1200- 1800 feet MSL with vis reduced 0-5SM over higher coastal terrain and in valleys.
Otherwise, variable high clouds above 15000 feet MSL and VFR conditions today and tonight.
No hazardous marine conditions are expected through Sunday.
Ca, Dense Fog Advisory until 9 AM PST this morning for Orange County Coastal Areas-Orange County Inland Areas-San Bernardino and Riverside County Valleys-The Inland Empire-San Diego County Coastal Areas-San Diego County Valleys.
PZ, None.
