Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
368 FXUS66 KSGX 251004 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 304 AM PDT Sat May 25 2024 .SYNOPSIS... Cooler today with gusty southwest to west winds in the mountains and deserts. Night and morning coastal low clouds will extend inland across all of the valleys and onto the lower coastal slopes of the mountains with only partial clearing this afternoon. High pressure to the south will bring warming for Sunday through Thursday. The marine layer will become shallower with night and morning coastal low clouds only extending into western portions of the valleys by the middle of next week. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Marine layer low clouds have filled in across the coastal basin and pushed into the coastal mountain slopes and through the passes this morning. Despite some holes in the cloud deck, it does appear to be around 2000-3000 ft thick in spots, sufficient for at least patchy drizzle this morning. The best chance of any measurable precipitation will be along the coastal mountain slopes. High-res ensembles showing at least some clearing across the Inland Empire and northern parts of Orange County this afternoon, but San Diego County won`t be lucky as it remains cloudy through the day. For the areas free of the marine layer, gusty onshore winds will continue across portions of the mountains and deserts through this evening, strongest this morning with a second weaker peak during the afternoon. Gusts will mostly be around 30-45 mph with isolated gusts to around 55 mph through the San Gorgonio Pass. Otherwise cooler today with highs 8-18 degrees below normal inland and around 4-7 degrees below normal near the coast. The trough that is bringing the cool and breezy weather today progresses eastward on Sunday, allowing for some warming and reduced coverage of marine layer low clouds. High temperatures will be around 5-10 degrees higher on Sunday away from the coast, though still several degrees below normal. We`ll also see better clearing of low clouds, except along the immediate coast and up to a few miles inland which could remain socked in through the day once again. Through about Wednesday, an upper level high centered over central Mexico will gradually shift westward and the north-south ridge axis will expand into the Desert Southwest but not quite towards So Cal. This will bring modest warming across the region on Monday with little variability through Wednesday. Highs will generally be close to seasonal normals during this period. The marine layer will be far more shallow with low clouds and fog limited to the coastal areas and western valleys each night and morning, and there will be a better chance of clearing each afternoon including on the Memorial Day holiday. Beyond Wednesday ensemble solutions begin to diverge on the progression and strength of an upper level low moving across the Pac NW and the subsequent ridging that follows behind it. About 50% of the ensembles favor more of a ridge/warmer weather, 25% a trough with cooler weather, and 25% somewhere in between. This continues into the weekend. Left NBM for high temperatures which maintains near seasonal weather through the end of the week. && .AVIATION... 250925Z...Coast/Valleys/Coastal Slopes...BKN-OVC with bases 2000- 3000 FT MSL are occurring this morning. Iso DZ/-SHRA 13z-17z Sat with locally reduced vis in SHRA. Scatter out across Inland Empire/inland Orange County 18z-22z Sat with limited clearing across San Diego and the coast this afternoon. Widespread BKN-OVC again Sat night-Sun morning. Mountains/Deserts...Mostly clear through Sat night. W-SW wind gusts of 25-40 kt over/east of mtns, strongest through 18z Sat. W-SW gusts of 20-35 kt 18z Sat-10z Sun. Local VIS 3-5 SM will occur in local BLDU. && .MARINE... West to northwest winds around 20 knots will occur in the outer coastal waters each afternoon and evening through Monday. && .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...EA