Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
933 FXUS66 KSGX 011031 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 231 AM PST Mon Dec 1 2025 .SYNOPSIS... Low clouds and patchy fog extending into the inland valleys this morning. Weak to locally moderate Santa Ana winds develop later this morning and weaken Tuesday for warmer and drier weather with far less marine layer cloud coverage. Chances increase for another round of weak to moderate Santa Ana winds late Wednesday into Friday, peaking Thursday. Gradual warming Thursday into next weekend with highs near seasonal normals. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Morning water vapor imagery shows the upper level trough continuing to progress southeast across the Desert Southwest, with the trough axis now moving over So Cal. Surface pressure gradients have turned offshore to the local deserts, currently around -1.5 mb LAX-DAG. Widespread low clouds and fog continue across the coastal areas and valleys, but these clouds should gradually clear to the coast later this morning as Santa Ana winds strengthen. Northeast to east winds are forecast to peak late this morning into the afternoon with gusts 30-45 mph below the passes, canyons, and near the foothills, with isolated gusts to 50 mph near the base of the Cajon Pass. Very weak ridging behind the departing trough and downsloping winds will lead to warming west of the mountains, where highs will be near to around 3 degrees above normal, but cooling across the mountains and deserts as cooler air moves in from the north. Santa Ana winds weaken tonight, turning back onshore by Tuesday morning. This will likely allow marine layer low clouds and fog to return to the coastal areas tonight. With the return of onshore flow and a trough beginning to drop down from the north, Tuesday will be slightly cooler with high temperatures near to slightly below normal. Much like the system today, ensembles have completely trended towards an inside slider track with the next trough Wednesday to Thursday. While some ensemble members are still showing very light precipitation, it would be more in the form of drizzle from a deepening marine layer Wednesday morning. Rain/mountain snow have been removed from the forecast with chances of measurable precipitation now less than 10%. Disappointing but not surprising. Onshore flow will strengthen ahead of the trough Tuesday, then as it passes in an almost identical track as this morning, another round of gusty Santa Ana winds develops behind it on Wednesday. Winds are forecast to peak on Thursday when there is around a 30% chance of a weak to moderate event. Offshore flow will likely continue into at least Saturday morning, gradually weakening each day. Upper level ridging slowly builds in from the west along with the offshore flow for gradual warming and drying along with mostly clear skies for thursday into early next week with highs warming to as much as 5-10 degrees above normal by Monday. && .AVIATION... 011030Z....Coasts/Valleys...Areas of low clouds in western valleys and coast based 1800-2400 feet MSL with inland vis 1-5SM will prevail through 16Z, but in somewhat random and variable fashion. Patchy low clouds based around 1200-1800 feet MSL will develop in coastal areas after 06Z into Tuesday. Offshore northeast winds 20-30 kts with locally higher gusts will continue in foothills this morning and spread into parts of inland valleys after 17Z. These will continue through the afternoon, diminishing after 02Z. Otherwise, mostly clear and VFR conditions will prevail today and tonight. && .MARINE... No hazardous marine conditions are expected through Friday. Tuesday. Offshore northeast winds 20-30 kts with locally higher gusts will continue in foothills this morning and spread into parts of inland valleys after 17Z. These will continue through the afternoon, diminishing after 02Z. Otherwise, mostly clear and VFR conditions will prevail today and tonight. && .MARINE... No hazardous marine conditions are expected today through Friday. && .BEACHES... Very high tides are forecast during the mornings Wednesday through Saturday this week, threatening minor tidal overflow and beach erosion. Chances of these impacts are higher Wednesday and Thursday mornings as elevated surf combines with the high tides. && .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/BEACHES...MM