Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
665 FXUS66 KSGX 250435 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 930 PM PDT Mon Jun 24 2024 .SYNOPSIS... Hot conditions will continue in the deserts through Thursday, with gradual cooling west of the mountains. There is a slight chance of showers and thunderstorms again in the mountains and high deserts Tuesday afternoon. Dry conditions will return from the middle of the week through the weekend, with marine layer low clouds and fog increasing near the coast and portions of the valleys. Some cooling will occur late in the week and next weekend in the deserts. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Skies were mostly clear this evening, with a few mid-level clouds. Stratus has formed south of around Rosarito Beach, Baja California, but the HRRR/HREF show only patchy low clouds along the San Diego County coast, with even few/no low clouds in Orange County. Late afternoon NKX sounding showed precipitable water has fallen slightly to 1.52 inches, though that is still quite high for June. Enough moisture remains in place Tuesday for a few mountain showers/thunderstorms to form in most favorable locations--over mountain peaks and in a few high desert locations of SBD County that get a convergence boundary between the afternoon west/southwest flow and south/southeast flow. Otherwise, hot weather will continue over the deserts with some cooling west of the mountains as the high over our area weakens and a trough gradually develops over the West Coast. As moisture aloft gradually decreases, we will have a decrease in the overnight temperatures and an increase in the marine layer stratus, with widespread stratus likely by Wednesday night. That trough will become more prevalent along the West Coast by Friday, with cooler weather spreading into the deserts then and more widespread coastal stratus over the weekend. No changes will be made to the excessive heat warning, in effect through Thursday in the desert. && .AVIATION... 250330Z...Coast/Valleys...There is a 20-35 percent chance of low clouds with bases 1000 ft MSL or lower developing along the San Diego County coast 09Z-15Z Tuesday. CIG impacts are not expected at TAF sites through Tuesday. Otherwise, FEW-SCT clouds at/above 15,000 ft MSL and unrestricted VIS through Tuesday. Mountains/Deserts...There will be a 10-15 percent chance of TSRA over the mountains and portions of the high desert again Tue afternoon, with CB bases near 10,000 ft MSL and tops to 30,000 ft MSL. Gusty outflow winds and reduced VIS VCTY TSRA. Otherwise, FEW- SCT clouds at/above 10,000 ft MSL and unrestricted VIS through Tue night. && .MARINE... No hazardous marine conditions are expected through Friday. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...Excessive Heat Warning until 8 PM PDT Thursday for Apple and Lucerne Valleys-Coachella Valley-San Diego County Deserts- San Gorgonio Pass Near Banning. PZ...None. && $$ PUBLIC...Maxwell AVIATION/MARINE...PG