Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
057 FXUS66 KSGX 241041 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 241 AM PST Mon Nov 24 2025 .SYNOPSIS... A warming trend is expected through Wednesday with high temperatures as much as 10-15 degrees above normal in the valleys. Weak to moderate Santa Ana winds are expected Tuesday through Thursday, with the strongest winds expected on Wednesday. Minor cooling on Thanksgiving with highs remaining well above normal, followed by more significant cooling Friday through early next week. A a trough of low pressure will bring a chance of showers early next week. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Areas of marine layer low clouds and patchy fog have returned to the coastal areas and far western valleys this morning. Any dense fog is limited to areas where radiation fog was able to develop due to lack of cloud cover. Clouds will clear to the coast by late morning. Otherwise clear skies will continue today. Weak upper level ridging begins to move in from the west, bringing warmer weather with highs right around normal. The upper level ridge moves overhead and amplifies into Wednesday. At the same time, surface high pressure builds over the Great Basin, driving Santa Ana winds across Southern California. Not much change in the wind forecast since yesterday, with chances of a weak to moderate event around 40% Tuesday, 80% Wednesday, and 50% on Thanksgiving. Winds will be purely gradient driven and confined to the usual passes, canyons, and coastal mountain slopes where wind gusts will peak around 35-45 mph on Wednesday. The combination of offshore winds and the strengthening upper ridge will bring considerable warming and drying west of the mountains. By Wednesday, high temperatures will be around 10-15 degrees above normal in the valleys, and around 5-10 degrees above normal elsewhere. Even the beaches could see highs in the mid to upper 70s. The ridge begins to shift east and weaken on Thanksgiving, allowing for minor cooling. Weak upper level troughing develops over the western US on Friday, bringing more cooling and a return of onshore flow. Beyond Friday the upper level pattern becomes a mess of short waves digging south, some tracking inland, some taking a more coastal route (only 12% of the ensemble members on Saturday), and some eventually closing off somewhere off the So Cal or northern Baja Coast Sun-Mon (27% of the members). Based on 00Z ensembles, precipitation chances have been pushed back to Saturday night (previously Saturday afternoon), with the highest chances (20-40%) now on Sunday afternoon into Monday. There is the potential for this low to track too far inland for any precipitation, but that is a small portion of the members. The more inland track, depending on how much the low deepens, could also set us up for a stronger Santa Ana event early next week. The 00Z EC and 06Z GFS basically sum up the two extremes - the EC completely dry with Santa Ana winds, and the GFS with a deep low tracking just off the coast and over an inch of rain (which is much wetter than its more reliable 00Z run counterpart). Needless to say, uncertainty is high. && .AVIATION... 241000Z...Coasts/Valleys...SCT-BKN patchy low clouds based 700-1000 ft MSL is currently fairly widespread along San Diego coastal areas to about 15 miles inland. Vis reductions 1-5 SM expected over elevated coastal terrain. Meanwhile, isolated areas of 200-300 ft cigs plus vis down to 1/4 SM in FG mostly in northern Orange County expected to improve slightly as marine layer builds further in towards 12-13Z this morning. FG likely to develop in parts of the Inland Empire 11-15Z. Expect cloud cover to be patchy all night, with intermittent scatter out due to weak easterly winds. Low clouds fully clear 15-17Z this morning. Patchy low clouds 500-800 ft MSL redevelop after Tue 04Z within about 10 miles of the coast, with vis 3-6 SM along coastal areas and 1-2 SM over higher coastal terrain (30-40% chance for vis 1/4-1/2 SM over elevated coastal terrain). Similar to this morning, expecting clouds to be in and out of sites. Mountains/Deserts...VFR conditions expected through tonight. && .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...None. PZ...None. && $$ PUBLIC...SS AVIATION/MARINE...CSP