Hot conditions continue through the weekend for inland locations. Cooler, windier, and cloudier conditions expected for the middle of next 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 next week with potential for Santa Ana winds.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
Heat will peak this weekend for inland locations with widespread minor and areas of moderate HeatRisk. High temperatures today and tomorrow are forecast to be 15 to 25 degrees above average. Multiple daily high temperature records are expected to be broken today and tomorrow away from the coast. 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. Additionally widespread cloud coverage is expected. Westerly winds will increase over the mountains and into the deserts in the afternoons and evenings. Strongest winds are expected Wednesday and Thursday when chances of wind gusts exceeding 45 mph are the highest.
Precipitation chances continue to trend down, with almost all ensemble solutions across global models showing no or only light precipitation. Consensus on timing of any rainfall has increased, with the highest chances centered on Wednesday, even if the highest chance is only 20 percent for the coastal slopes of the mountains. For lower elevations chances of rain are 15 percent or less. The track of the trough will keep the bulk of the moisture to our north. If any rain develops, coast and valleys are expected to see 0.10" or less of rain accumulate, with the coastal slopes of the mountains having a 20 percent chance of exceeding 0.10". Thursday is expected to be the coolest day with temperatures near normal, continued cloud coverage, and some lingering breezy winds.
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 and another uptick in temperatures. 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 things will have an impact on the strength and duration of any Santa Ana winds that develop.
281710z, Increasing confidence for low clouds 400-800 ft MSL to come back along San Diego County coastal areas tonight, lesser confidence in Orange County. Confidence in timing is low to moderate with best chances for low clouds between 08-18Z Sun, though clouds may be delayed until 10-12Z. Vis reductions 2-5 sm, with higher terrain obscured in fog. Low clouds scattering 16-18Z Sun.
Otherwise, inland areas partly to mostly clear with clouds AOA 20K ft MSL through the TAF period.
Breezy northwest winds this afternoon with gusts near 20 kts near San Clemente Island. Otherwise, no hazardous marine conditions expected through Wednesday.
Ca, None. PZ, None.
