938 FXUS66 KSGX 270402 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 902 PM PDT Sat Jul 26 2025 .SYNOPSIS... A trough across the West Coast will continue cooler than normal weather through the weekend. High pressure will expand further west, bringing a warming trend Sunday into Tuesday, with temperatures staying near average through the end of next week. Breezy west winds will continue this weekend across mountains and deserts, while the marine layer provides low clouds at times west of the mountains. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... A few high clouds continue to lift northeast across the region this evening, and low clouds are developing off the coast. The 00Z KNKX sounding shows the marine inversion based near 2300 ft MSL, deep enough to allow low clouds to spread into parts of the inland valleys overnight. Upper level high pressure over the southeast US will slowly shift westward and expand into SoCal through midweek, then the upper level pattern remains fairly stagnant through the end of the week with the high centered somewhere near TX and weak troughing along the West Coast. This will bring gradual warming through Wednesday with little day-to-day variation into next weekend. On Sunday, high temperatures will be around 7-12 degrees below normal in the mountains and valleys, and around 3-5 degrees below normal near the coast and deserts. By Wednesday highs will return to near normal, or around the mid 70s to low 80s for the coastal areas, mid 80s to mid 90s in the valleys, 70s and 80s in the mountains, 90s to around 100 in the high desert, and 105-110 in the low deserts. With the trough still in the vicinity and southwest flow aloft prevailing, ensembles remain predominantly dry through the end of the week. A few members from the EPS and GEFS have an increase in Precipitable Water as monsoon moisture tries to sneak in, but they are very much in the minority. At this point the chance of moisture returning is less than 5% for the rest of the week. And in case you thought this may mean we are free from No Sky July, marine low clouds will hold on through the week, though clouds will become confined to the coastal areas as the marine layer becomes more shallow. && .AVIATION... 270300Z....Coasts/Valleys...Low clouds based 1800-2300 ft MSL are slowly developing over coastal waters. Clouds will overtake San Diego County in the next few hours. Slowly filling into Orange County around 09z and most of the Inland Empire by 12z. Scattering to the coast by 17-18Z. Clouds return to coastal areas after 03z with lower bases 1200-1800 ft MSL. Mountains/Deserts...Mostly clear with VFR conditions through Sunday evening. && .MARINE... No hazardous marine conditions are expected through Thursday. && .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...KW