Warmer today for the coast to the mountains with weaker winds for inland areas. A low pressure system from the northwest will bring much cooler high temperatures for the mountains and deserts on Thursday with stronger and gusty west to northwest winds for the mountains and deserts for Wednesday night and Thursday. Then warmer for Friday into the weekend with offshore lower-level flow and strengthening east to northeast winds. Moisture from the east could bring some showers for Sunday and Monday.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
(today through Thursday), The low pressure system that brought stronger onshore flow to southern California on Monday spread cooling inland and brought stronger and gusty southwest to west winds to the mountains and deserts. The late afternoon NKX sounding showed multiple weak inversions below 4500 feet. Satellite imagery shows low clouds over portions of the coastal waters and portions of the coast and western valleys. The greatest coverage over land areas as of 2:30 AM was over the western valleys in San Diego County.
As this low pressure system moves eastward and inland today, high temperatures from the coast to the mountains will warm, by around 5 degrees to locally degrees for the inland valleys, inland Orange County, and the lower elevations of the mountains. With the warming, high temperatures for today will range from the mid to upper 60s near the coast to the mid 70s to lower 80s for the Inland Empire. The deserts will be a few degrees cooler with high temperatures for the lower deserts in the mid to upper 80s.
An approaching low pressure system from the northwest will begin to spread cooling inland on Wednesday with high temperatures for the coast and valleys a few degrees cooler than today. Much greater cooling will spread inland on Thursday with high temperatures 10 to locally 15 degrees cooler for the deserts onto the desert slopes of the mountains. There will be stronger west to northwest winds for the mountains and deserts for Wednesday night into Thursday morning with gusts to 40 to 50 mph and isolated gusts to 65 mph.
(Friday through Monday), Friday is expected to be warmer with winds becoming offshore. For the weekend into early next week, a closed low pressure system is expected to be over Baja, southern California, and the adjacent eastern Pacific with differences in the placement of the center of this upper low. Current guidance has the greatest warming west of the mountains on Friday and Saturday with east to northeast winds strengthening along and below the coastal slopes of the mountains. By Sunday and Monday, depending on the placement of the upper low, it could begin to entrain some moisture from the south and southeast with increasing clouds and a slight chance of showers.
031030z. Coast/ western valleys, Areas of low clouds will continue to expand in coverage through 15Z. Bases will be 1500-2200 feet MSL, with local vis restrictions on higher coastal terrain and inland. Scatter out 16-18Z. Areas of low clouds will redevelop after 04Z overnight into Wednesday more confined to coastal areas. Bases a little lower, around 500-1500 feet MSL.
Otherwise, VFR conditions: clear today and some high clouds tonight.
Stronger northwest winds return late Wednesday into Thursday in the outer waters, producing choppy conditions that may become hazardous. Otherwise, no hazardous marine conditions are expected through Saturday.
Ca, None. PZ, None.
