Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
330 FXUS66 KSGX 232047 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 147 PM PDT Mon Sep 23 2024 .SYNOPSIS... Dry and warmer today, with high temperatures around 4 to 8 degrees above average for inland areas. Not much change on Tuesday then slightly cooler for Wednesday and Thursday. Friday may be a little warmer, followed by slow cooling for next weekend with increasing spread in the high temperature guidance due to the uncertain placement of a weak low pressure system in the vicinity of southern California. Night and morning coastal low clouds will spread into portions of the western valleys late each night. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... This afternoon...The marine layer low clouds cover the coastal waters and persist at most beaches. Low clouds and fog are likely to begin pushing inland around sunset and may not spread as far inland tonight as last night due to the marine layer being a little shallower. The shallower marine layer will also increase the chances for patchy dense fog on elevated coastal terrain. Temperatures are generally warmer than at this time yesterday everywhere except the coastal areas where they near or a couple of degrees lower. From previous discussion... A weak low pressure trough over SoCal with a closed upper low about 200 miles to the west. The low pressure trough will continue to weaken and high temperatures today will be around 5 degrees warmer than Sunday, near average near the coast to 4 to 8 degrees above average inland, mostly into the 90s for the inland valleys and 102 to 108 for the lower deserts. Not much change is expected for Tuesday, then a weak low pressure system off the California coast may bring a few degrees of cooling for Wednesday and Thursday as the upper high gets displaced eastward into the Great Basin. That weak low pressure system may move farther off the California coast on Friday allowing the upper high to expand westward, with high temperatures slightly warmer. For next weekend, that weak low pressure system may move back towards southern California with differences in model placement and timing. The deterministic NBM has slight cooling for Saturday and Sunday, but with increasing spread in the high temperature guidance. && .AVIATION... 232045Z...Coasts/Valleys...Low marine stratus (based around 600- 900ft MSL, tops near 1500ft MSL) mainly over the coastal waters and beaches this afternoon. Low stratus builds in again at coastal sites around 02-04z this evening with similar bases and tops. Local vis 1- 3SM in BR for higher coastal terrain and valleys. Confidence in return time of around 24/03Z at KSAN is moderate. Mountains/Deserts...Mostly clear skies with unrestricted VIS expected 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...PG AVIATION/MARINE...Small