Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
737 FXUS66 KSGX 302044 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 144 PM 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. It will turn 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. There is a slight chance of showers Saturday night and Sunday morning. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Coastal clouds cleared quite well today and it`s a little cooler than this time yesterday. 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. Low clouds and fog should cover most or all 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, 60s at the coast, and upper 50s to mid 70s in the mountains. These numbers are near or slightly above normal away from the coast. A longwave trough sags southward Friday and Saturday, increasing our onshore flow again, increasing westerly winds and deepening our marine layer for the weekend. A more defined low pressure trough will swing through CA Sunday. Some ensemble members, mostly from the GEFS indicate some rain, mainly Sunday morning, from the coast to the mountains. Euro ensemble members show a much lower chance of rain, and Canadian members fall in between. We introduced a slight chance of measurable rain late Saturday night through Sunday morning. With more confidence you can count on cooler weather, breezier onshore winds, and more clouds this weekend, particularly Sunday. Some weak high pressure returns Monday and Tuesday to reverse the cooler, cloudier trend back toward a warmer, sunnier normal. && .AVIATION... 302040Z...Coasts/Valleys...Mostly clear with visibilities unrestricted. Low clouds with bases 800-1200 FT MSL tops around 1800 feet MSL will be moving onshore after about 02Z. Reduced VIS of 1 SM or less where low clouds and terrain intersect. Low clouds reaching KONT and KRNM late tonight. Scatter out 15-18z Wed. Otherwise, clear skies with unrestricted vis through tonight. && .MARINE... No hazardous marine conditions are expected through Sunday, but conditions approach hazardous on Sunday. && .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