A cooling trend will continue through Friday. Chances of precipitation are in the forecast for locations over and west of the mountains Thursday through Saturday morning. Dry conditions are expected to return Sunday with a warming trend and prevailing offshore flow expected into next week.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
Visible satellite this afternoon was showing a swath of high clouds over Southern California. Ground observations are indicating a few areas of low clouds and some lingering haze from this morning's dense fog. Onshore flow will strengthen as an upper level low continues to dig south parallel to California before moving east into Baja California late Friday/early Saturday. The increased onshore flow will keep areas of low clouds and fog that develop overnight reaching well into the valleys and along coastal slopes of the mountains.
The aforementioned upper level low will also bring slight chances of showers to the area Thursday through early Saturday. Scattered showers could begin as early as Thursday morning, with rain likely continuing into Friday. About 50 percent of ensemble solutions keep the potential of rain over the area into at least Saturday morning. Latest high resolution guidance is indicating hourly rainfall rates will range from 0.05-0.25" per hour. Rates at or near 0.25" per hour will be fairly isolated and most likely occur Friday. Chances of rainfall totals exceeding 0.50" from Thursday through Saturday, are 10-20 percent for the coast and valleys and 30-40 percent in the mountains. The mountains have a 10-15 percent chance of exceeding 1 inch of rain. Snow levels will fall to 6500 to 7000 ft by Saturday morning. 1-3" of snow are expected around 7000 ft, with slightly higher totals expected above 8000 ft.
Today is trending cooler than yesterday, with further cooling expected into Friday. By the weekend, conditions west of the mountains are expected to warm a few degrees with continued cooling in the deserts. By Monday, widespread warming is expected with increasing temperatures each day into Wednesday. Ensemble guidance is in agreement that a ridge of high pressure will set up over the West Coast on Monday and remain in place into next Wednesday. With the upper level low to our east by Sunday, offshore winds are expected to develop. Current ensemble guidance has an 80 percent chance of weak offshore winds developing, with a 20 percent chance of weak to moderate offshore winds developing.
211830z. Coast/Valleys, Prevailing FEW clouds around 800ft MSL and SCT-BKN clouds AOA 15,000ft MSL with VIS generally 5SM or better. Low clouds redevelop and move inland again this evening beginning around 02z Thur, with bases around 1000-1500ft MSL, locally lower closer to 800ft MSL. VIS may drop to or below 5SM in some valleys and where clouds intersect coastal terrain. Low clouds will rise a bit closer to 1500-2000ft MSL after 12z Thur with improving VIS. Clouds scatter out after 16z and push back towards the coastline, but lingering stratus around 2500-3500ft MSL expected for coastal areas through Thursday afternoon.
.Otherwise, Variable high clouds above 15,000 feet MSL and VFR conditions today and tonight.
No hazardous marine conditions are expected through Sunday.
Ca, None. PZ, None.
