One more day of widespread record breaking temperatures today with highs 15 to 20 degrees above average for inland locations. Cooler, windier, and cloudier conditions expected for the middle of week. Slight chance (15-20 percent) of light precipitation on Wednesday for areas along and west of the mountains. Drier and warmer conditions for the end of the week with potential for Santa Ana winds.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
Visible satellite at 10 AM was showing a fog bank along the southern Orange County beaches, extending south towards Mission Beach in San Diego County. Lifeguards have reported visibility of 1/8 to 2 miles where the clouds are reaching land. Visibility should improve by later this afternoon but areas of low clouds and fog are expected redevelop overnight into Monday morning. One last day of record breaking temperatures for inland locations can be expected today. By Monday the high pressure aloft will weaken enough to kick off a cooling trend through mid-week. Highs Monday will be 5 to 10 degrees cooler than Sunday for inland locations.
Weak troughing over the US West Coast will continue to cool conditions back to near seasonal average by Wednesday. A few additional degrees of cooling on Thursday will make it the coolest day of the week for most locations. Widespread cloud coverage can be expected for the middle of the week. Westerly winds will increase over the mountains and into the deserts in the afternoons and evenings Tuesday through Thursday. Strongest winds are expected Wednesday and Thursday with peak gusts of 40 to 55 mph.
Precipitation chances on Wednesday are holding steady at around 15 to 25 percent chance of measurable rain, with the highest chances on the coastal slopes of the mountains. The track of the trough will keep the bulk of the moisture to our north. Rainfall totals for the coast and valleys will be 0.10" or less, with the coastal slopes of the mountains having a 20 to 25 percent chance of rainfall totals exceeding 0.10".
Once the aforementioned low is to our east, the majority of global model ensemble solutions show it digging south into the Great Basin Friday and Saturday. This would turn the pressure gradient offshore, bringing chances of Santa Ana winds, dry air, and another uptick in temperatures west of the mountains. While most guidance is in agreement on this general pattern, there remain differences in how far south the low will dig and how fast it will continue to move east. Both of those factors will have an impact on the strength and duration of Santa Ana winds that develop. Latest guidance from the CW3E WRF ensemble has a 60 to 80 percent chance of a weak Santa Ana wind event Friday and Saturday, with a 40 to 60 percent chance of a weak to moderate Santa Ana wind event.
291640z, Areas of clouds and fog off the coast will continue to push over coastal areas through this morning. There is low to moderate confidence that VCTY KSAN/KCRQ see low clouds near 200-400 ft MSL and vis 3-5 sm. Low clouds scattering out completely between 18-19Z. Low clouds expected to return 04-06Z Mon and push further inland overnight within 5-10 miles of the coastline. Bases will be higher near 600-1000 ft MSL with higher coastal terrain obscured in fog; clouds scattering near 16-18Z Mon.
Otherwise, partly cloudy skies for with clouds AOA 20K ft MSL through the TAF period.
No hazardous marine conditions expected through Wednesday. Breezy northwest winds near 20 kts across all marine areas on Thursday.
Ca, None. PZ, None.
