Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
686 FXUS66 KSGX 301548 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 848 AM PDT Tue Apr 30 2024 .SYNOPSIS... Fair and seasonal weather will continue this week. The marine layer will provide coastal clouds nights and mornings, more extensive on Wednesday morning. Warmer on Thursday before low pressure and onshore flow increase this weekend. That will bring a cooling trend, more coastal clouds and brisk westerly winds in the mountains and deserts Saturday through Monday. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... A stronger coastal eddy seems to be responsible for deepening the marine layer a little bit and extending coastal clouds a little farther inland this morning. These will clear by late morning and we`ll have plenty of sunshine regionwide. A low pressure trough will swing down into the northwestern U.S. tonight and Wednesday. The increased onshore flow will boost westerly winds in our mountains and deserts this evening, with top localized gusts achieving 35-50 mph, such as in the San Gorgonio Pass. The trough will also strengthen our coastal eddy and extend low clouds farther inland by Wednesday morning. The low clouds should cover most of the coastal basin west of the mountains. A brief ridge builds up Thursday, with a hint of offshore flow, which will generate our highest max temperatures of the week: low 80s in the Inland Empire and high desert, low-mid 90s in the low desert, 70s across much of the coastal basin, and 60s at the coast and in the mountains. These numbers are near or slightly above normal. A longwave trough sags southward Friday and Saturday, increasing our onshore flow again, increasing westerly winds and deepening our marine layer for the weekend. Some ensemble members, mostly from the GEFS indicate some light rain, mainly Sunday morning, from the coast to the mountains. Euro ensemble members are much drier, and Canadian members fall in between. The chance of measurable rain is so slight at this point, below the threshold of even mentioning the chance in the forecast... yet. Stay tuned. In the meantime, count on cooler weather, breezier onshore winds, and cloudier weather this weekend. Some weak high pressure returns Monday to reverse the cooler, cloudier trend back toward a warmer, sunnier normal. && .AVIATION... 301540Z...Coasts/Valleys...Low clouds with bases 800-1200 FT MSL Tops around 1800 feet MSL. Reduced vis of 1 SM or less where low clouds and terrain intersect. Scatter out 15-18z Tue. Otherwise, clear skies with unrestricted vis through tonight. && .MARINE... No hazardous marine conditions are expected through Friday. && .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...MM AVIATION/MARINE...Small