Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
653 FXUS66 KSGX 121626 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 926 AM PDT Wed Jun 12 2024 .SYNOPSIS... Marine layer night and morning low clouds and fog will persist along the coast, into the valleys at times, each day into next week. A few degrees of warming is expected for the coast and valleys today, with widespread cooling Thursday. Another bout of warming is expected for Friday and Saturday, most noticeable in the lower deserts. Cooler conditions will return Sunday through the middle of next week. Periods of gusty southwest to west winds are expected in the mountains and deserts each afternoon and evening into next week. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Visible satellite this morning showed low clouds had filled in most of the coastal basin overnight. As of 9 AM, clouds are slowly beginning to clear the valleys. Low clouds are expected to linger at some beaches this afternoon. With better clearing west of the mountains today, coast and valley locations are expected to be 5 to 12 degrees warmer than yesterday. In and east of the mountains, highs will be a mix of a few degrees warmer and a few degrees cooler than yesterday. The mountains and High Deserts are the places likely to experience temperatures a few degrees cooler than yesterday. A weak low pressure system will move inland through southern California late Thursday. As a result, high temperatures on Thursday will be a few degrees cooler than today for most areas from the coast to the deserts. The cooling trend will be brief as a weak high pressure system sets up over southeastern California, southern Nevada, and western Arizona Friday and Saturday. For Friday, highs will be a degree or two warmer for the coast; 2-4 degrees warmer for the valleys; 4-8 degrees warmer for the mountains, the Apple and Lucerne Valleys, and the low deserts. Warming will continue into Saturday, which will be the peak of this brief warming trend. Highs are expected to be 3-5 degrees above average for the coast and western valleys and 5-10 degrees above average for portions of the eastern valleys, mountains, and deserts. Moderate to locally major heat risk is expected in the low deserts, with ares of moderate heat risk in the Inland Empire, mountains, and High Desert. A low pressure system moves inland through the western states Sunday into the middle of next week, bringing cooler conditions to the area. The deserts may experience a few degrees of cooling each day through Tuesday while the coast into the valleys may begin to slowly warm by Tuesday. The increase in onshore flow with the passing trough will also allow for the marine layer to deepen again with low clouds reaching into the valleys. && .AVIATION... 121545Z...Coast/Valleys...Low clouds based 900-1100 ft MSL with tops to 2500 ft MSL. Coastal airports expected to clear today as the low clouds should clear back to over the coastal water. After 13/0300 UTC this afternoon low clouds based 900-1100 ft MSL with spreading inland, reaching KONT around 10Z but unlikely to reach KSBD. Areas of VIS 2-4SM in fog where clouds and terrain intersect. Confidence in SCT conditions at KSAN mid-afternoon today is moderate. Mountains/Deserts...SKC with unrestricted VIS through today. && .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...CO AVIATION/MARINE...Small