Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
646 FXUS66 KSGX 242026 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 126 PM PDT Tue Sep 24 2024 .SYNOPSIS... Continued dry today, with high temperatures around 5 to 10 degrees above average for inland areas. There will be a few degrees of cooling for Wednesday and Thursday followed by slight warming on Friday. A little cooler for the weekend, then a little warmer for early next week. Night and morning coastal low clouds will continue to spread into portions of the western valleys late each night, with only minor day-to-day fluctuations. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... This afternoon...Temperatures are near or a couple of degrees lower than at this time yesterday in the coastal and valley areas subject to the influence of the marine layer. Elsewhere, temperatures are mostly a few degrees warmer. Marine layer low clouds linger at the immediate coast and are expected to begin spreading inland around sunset and could extend 20-30 miles inland by sunrise on Wednesday. Little change in the marine layer depth is expected. The synoptic pattern continues to evolve mostly as anticipated. The upper low off the coast continues to move north in response to a dynamic shortwave moving southeast out of the Gulf of Alaska while the upper high becomes nearly stationary over the Great Basin. From previous forecast... High temperatures this afternoon will be similar to yesterday. Temperatures in the coastal areas will be near seasonal averages and around 5 to 10 degrees above average for the mountains, deserts, and inland valleys. High temperatures for the coast and valleys may be a few degrees cooler on Wednesday and Thursday, with night and morning coastal low clouds extending a little farther inland into the western valleys as the marine layer deepens. Not much change in high temperatures is expected for the mountains and deserts, although current model runs have trended warmer than previous runs. An extensive upper level low pressure trough will remain off the coast, with high pressure to the east bringing slight warming for Friday. A little cooler for Saturday and Sunday as that low pressure trough moves nearer to the California coast. High temperatures a few degrees cooler will spread inland on Saturday and Sunday, with Sunday high temperatures a few to around 5 degrees below average for the coast and valleys and around 4 to 8 degrees above average for the deserts. High temperatures for the lower deserts will be 100 to 105. Then a little warmer for the coast and valleys on Monday as low pressure along the coast weakens. && .AVIATION... 242020Z...Coasts/Valleys...Mostly clear early this afternoon, except near the immediate coast in SD County with BKN bases near 900-1200 feet MSL. Probabilities of BKN cigs increase after 01Z this evening for San Diego Co coastal TAF sites. High confidence on clouds spreading to inland valleys after 03Z. Low to moderate confidence exists for cigs to reach the Inland Empire with a 40% chance of this occurring at KONT between 08-16Z Wed. Similar bases/tops/vis expected. Clouds scattering out near the coast once again near 17-19Z Wed with moderate confidence. Mountains/Deserts...Low clouds approaching foothills in San Diego county; otherwise, mostly clear through tonight into Wednesday. && .MARINE... No hazardous marine conditions are expected through this weekend. && .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...PG AVIATION/MARINE...APR