878 FXUS66 KSGX 190944 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 244 AM PDT Thu Jun 19 2025 .SYNOPSIS... Low pressure moving inland into the western states will bring cooling through Saturday with Saturday high temperatures as much as 8 to 12 degrees below average for the mountains, inland valleys, and high desert. There will gusty southwest to west winds during the afternoons and evenings for the mountains and deserts with the stronger gusts to 35 to 45 mph. The marine layer will deepen with night and morning coastal low clouds spreading farther inland to the valleys. For Sunday through Wednesday, low pressure will weaken some, but remain across the area. High temperatures will warm 5 to locally 10 degrees but remain below average by around 5 degrees. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... .SHORT TERM (Today through Saturday)... The marine layer has deepened to around 2000 feet with satellite imagery showing coastal low clouds covering all of the Orange County coastal plain and the western half of the San Diego County valleys. Through sunrise, the low clouds may begin to spread into far southern and far western portions of the Inland Empire. Wednesday high temperatures were a few degrees cooler than Tuesday for the coast and valleys. A low pressure system moving inland into the western states will spread cooling inland through Saturday. Saturday high temperatures will be as much as 8 to 12 degrees below average for the mountains, inland valleys, and high desert with high temperatures ranging from around 70 near the coast to the mid 70s to lower 80s for the Inland Empire with around 100 for the lower deserts. The marine layer will deepen to around 2500 feet for Saturday with night and morning coastal low clouds spreading farther into the valleys. Stronger onshore flow will also bring stronger and gusty southwest to west winds for the deserts onto the desert slopes of the mountains with the stronger gusts during the afternoons and evenings to 35 to 45 mph. && .LONG TERM (Sunday through Wednesday)... Low pressure will weaken some, but remain across the area. High temperatures will warm 5 to locally 10 degrees but remain below average by around 5 degrees. The marine layer will decrease in depth to around 1500 to 2000 feet with night and morning coastal low clouds spreading inland into the western valleys. && .AVIATION... 190930Z....Coast/Valleys...Low clouds have filled in quite uniformly across the coasts and up to 15-20 miles inland. Bases are sitting around 1000-1300ft MSL with tops to about 1700-1900ft MSL, though bases may fall some by 12-14z. closer to 800-1100ft MSL. These clouds could filter into the southern and western Inland Empire, with a 35-40% chance of CIGs at KONT anytime between 11z-16z. VIS restrictions limited to where terrain intersects the cloud layer and within inland valleys. Clouds clearing to the coasts by 17-19z. Low clouds develop again tonight and push back inland after 01z Friday with slightly higher bases closer to 1500ft more inland extent. Mountains/Deserts...Clear skies and unrestricted VIS through early Friday morning. && .MARINE... Northwest winds may gust close to 20 knots near San Clemente Island Friday afternoon and evening. Otherwise, no hazardous marine conditions are expected through Sunday. && .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...17 AVIATION/MARINE...Munyan