Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
217 FXUS66 KSGX 220951 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 251 AM PDT Sun Sep 22 2024 .SYNOPSIS... Warming trend for early this week. The marine layer will become shallower early this week, becoming confined to the coast and portions of the western valleys. For the middle to end of the week, minor daily fluctuations in high temperatures are expected. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Visible satellite at 2 AM was showing low clouds had filled in along the coast and were reaching into portions of the western valleys. High temperatures today will reach the mid to upper 70s for coastal areas, the 80s to low 90s for the valleys, 70s to low 80s for the mountains, low 90s for the High Desert, and 100 to 105 degrees for the low desert. Additional warming is expected into Monday, with most places 3 to 5 degrees warmer than today. For Tuesday, the latest guidance has highs similar to Monday for most locations with only a degree or two of difference. For the middle of the week, a trough of low pressure will build off the US West Coast with a ridge of high pressure over the desert southwest. There remains uncertainty in the upper level pattern and which system will have the most influence over Southern California`s weather. The current forecast follows the NBM and has slight day to day temperature variations for Wednesday through Friday with more of a cooling trend for the weekend. Temperature guidance for the upcoming weekend shows increasing spread for coast and valley locations from Friday through Sunday. That spread indicates temperatures may trend warmer or cooler than currently forecast as the models single in on a solution. The marine layer will become shallower through Wednesday. Low clouds and fog will be mostly confined to the coastal areas, inland Orange County and the western portions of the San Diego County valleys. Depending on how the upper level pattern shakes out, the marine layer may recover slightly for the middle to end of the week. If the troughing pattern becomes dominate over Southern California for next weekend, the marine layer may deepen far enough for low clouds and fog to reach portions of the Inland Empire. && .AVIATION... 220900Z...Coasts/Valleys...Low marine stratus based near 1000-1500ft MSL (topped to 2000-2500ft MSL) continues to gradually fill in in the San Diego hills/valleys and into Orange County at this hour. There remains a 40% chance for CIGs and/or reduced VIS at KONT (and a 20% chance for KSBD) after 12-13z. Local vis 1-3SM in BR for higher coastal terrain and valleys. Low clouds clear to beaches by 17-18z, giving way to mostly clear skies through this evening. Low clouds push back ashore in San Diego County after 00z, closer to 06- 09z for Orange County. These will have similar bases/tops but may be 100-200ft lower than this morning. Mountains/Deserts...Mostly clear skies with unrestricted VIS expected through Monday morning. && .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...CO AVIATION/MARINE...Munyan