600 FXUS66 KSGX 232027 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 127 PM PDT Mon Jun 23 2025 .SYNOPSIS... A few degrees cooler today with below average temperatures. Tuesday will be a few degrees warmer with gradual warming trend continuing through the end of the week. The marine layer will bring night and morning low clouds to coastal areas through the week. Low clouds are expected to reach into the valleys at times, most likely during the first half of the week. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... A weak coastal eddy continues to spin in the California Bight. A few patches of low clouds remain along the immediate coast as of 1 PM. High resolution model guidance is indicating the possibility of patchy drizzle developing tonight into Tuesday morning, mainly along the coast. The marine layer is expected to remain 2000 to 2500 ft deep through Wednesday while we remain under cyclonic flow aloft as a trough moves across the West Coast. A few degrees of warming will occur on Tuesday, but highs will remain about 5 to 10 degrees below average. An additional 4 to 8 degrees of warming is expected for inland areas on Wednesday. This will bring conditions back to within 5 degrees below normal for Wednesday. An area of high pressure will build in from the southeast Thursday into the weekend. Current ensemble guidance is showing the ridge axis setting up mainly over the low deserts. This would bring more noticeable warming there Friday through Monday. Chances of the low deserts exceeding 110 degrees are highest on Sunday and Monday at 60 to 80 percent. There are some indications that the position of the high pressure would allow for a moisture surge from the southeast into the low deserts over the weekend. If that were to occur, that would keep high temperature readings lower. Conditions are expected to warm up west of the mountains, with temperatures in the valleys reaching into the 90s. Chances of the Inland Empire exceeding 100 degrees on Sunday and Monday are mostly 20 to 30 percent, locally up to 50 percent in the eastern portion of the Inland Empire. The building high pressure aloft should keep the marine layer shallower and more confined to coastal areas. && .AVIATION... 222100....Coast/Valleys/Coastal Mountain Slopes...Mostly VFR conditions this afternoon. Low clouds with bases 1200-2500 feet MSL push inland again around 03-06z Tuesday, filling the entire coastal basin by 10z. -DZ and BR possible throughout coastal basin, highest likelihood from 11-15z Tuesday morning. Slight (30%) that VIS could down to 3SM in parts of the Inland Empire as a result of -DZ/BR. Otherwise, low clouds retreat to the coast 16-19z. .Mountains/Deserts...Clear skies and largely unrestricted VIS through Tuesday afternoon. Wind gusts 25-35 kts this afternoon and evening with isolated gusts to 45 kts through mountain passes. Mod up/downdrafts near mountain ridges. Stronger gusts begin to subside by 04-06z Tuesday. && .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...CO AVIATION/MARINE...Westerink