Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
207 FXUS66 KSGX 241602 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 902 AM 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 morning...At about 2200 ft, the marine layer is slightly deeper than yesterday so that fog is affecting terrain at slightly higher altitudes. Also, low clouds have spread 25-30 miles inland - a few miles farther inland than yesterday. The inversion is about as strong as yesterday so we can expect a clearing pattern similar to yesterday, with low clouds lingering at the beaches into this afternoon. The synoptic pattern is evolving a little faster than previous model runs had indicated, with the short-lived Rex Block already breaking down. The upper high has been displaced eastward and is now over the Great Basin while the upper low west of Point Conception is being drawn northward in response to a vigorous shortwave moving southeast from the Gulf of Alaska. Not much change in high temperatures is expected for today. 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... 241535Z...Coasts/Valleys...Low clouds near 700-1200 feet MSL with tops near 1600 feet will slowly recede out of the valleys this morning with improving visibility. Scatter out nearing the coast by 17-18Z; partial / intermittent clearing at the immediate coast through the afternoon. Low clouds will push ashore near 00-02Z with moderate confidence and gradually spread inland overnight into Wednesday, with similar bases/tops/vis and a little greater coverage inland. Clouds scattering out near the coast once again near 17-19Z Wed with moderate confidence. Mountains/Deserts...Mostly clear today and tonight. && .MARINE... No hazardous marine conditions are expected through Saturday. && .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