The marine layer will deepen overnight into Wednesday morning before becoming shallower again for Thursday into early next week. Areas of drizzle or light rain near the coast are possible tonight into Wednesday, with no impacts expected. Wednesday will be a few degrees cooler than today, before warmer conditions Thursday into early next week. The pressure gradient will rapidly switch from onshore to offshore for the middle to end of the week with periods of gusty Santa Ana winds.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
This evening, the marine layer is now about 4000 ft deep and areas of low clouds have formed from the coast to the mtn foothills. By Wednesday morning, the marine layer is expected to be about 4500 ft deep and the low clouds are likely to fill in all areas west of the mtns. If the saturated layer becomes thick enough, there could be some drizzle west of the mtns later tonight. Sfc pressure gradients continue to trend onshore and westerly winds are locally gusting 25-45 mph in the wind-prone passes and canyons at this hour.
From previous discussion, As the upper level low moves southward into the Great Basin, a 1030 mb surface low will develop. This will bring periods of gusty Santa Ana winds to foothills and coastal mountain slopes; warming conditions; and mostly clear skies across the area. Gusty north winds will develop through and below the Cajon Pass on Wednesday afternoon with more widespread and stronger northeasterly winds for Wednesday night into Thursday morning along and below the coastal slopes of the mountains with peak gusts 40 to 50 mph, locally up to 55 mph. Northeast to east winds will continue for Thursday afternoon into Friday morning, but with decreasing coverage and strength. Gusts on Friday are expected peak at 35 to 40 mph. Lowest daytime humidity on Thursday and Friday for the valleys and inland coastal areas will fall to 15 to 20 percent.
A few degrees of cooling is expected into Wednesday, with highs a few degrees below average. A gradual warming will occur Thursday, with further warming expected through the weekend into early next week. By Tuesday, highs will be 10 to 15 degrees above average for inland areas.
030400z. Coasts/Valleys, Patchy low clouds based 2200-3200 ft MSL with tops to 4000 ft MSL will continue to move to cover the coastal basin by about 10Z this evening. Patchy -DZ expected, especially near the coastline 10-16Z, bringing areas of lowered vis 4-6 SM on occasion. Clouds will intermittently scatter out overnight, with fuller clearing from east to west 14-18Z. North to northeast winds gusting 20-30 kts through and downwind of the Cajon pass after 17Z (including vcnty KONT) and continuing in areas through the TAF period.
Mountains/Deserts, VFR conditions through the period with FEW-SCT high clouds AOA 20 kft. West winds gusting 25-40 kts through mountain passes and along east-facing slopes will weaken 15-18Z, before turning north to northeast and strengthening again along the coastal slopes and foothills. Mod up/downdrafts near mtns.
No hazardous marine conditions are expected today through Saturday.
High tides of 6.5 to 7.5 feet are forecast to occur each morning Wednesday through Friday, threatening minor tidal overflow and beach erosion. Chances of these impacts are higher Wednesday and Thursday mornings as elevated surf up to 4-6 feet combines with the high tides, mostly in San Diego County. Check the Coastal Hazard Message for details.
Ca, Beach Hazards Statement through Friday morning for Orange County Coastal Areas-San Diego County Coastal Areas.
PZ, None.
