Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
786 FXUS66 KSGX 291546 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 846 AM PDT Mon Apr 29 2024 .SYNOPSIS... The upcoming week will be warm with dry weather across the region. The marine layer will stay relatively shallow, where low clouds and fog will be primarily closer to the coast and in some western valleys each night and morning through the week. Breezy west winds will occur across mountain and desert regions each afternoon and night through Wednesday. Pockets of breezy offshore winds should develop Wednesday into Thursday. Onshore flow and a cooling trend appears on the horizon by the weekend. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Coastal low clouds, with fog on the higher coastal terrain, developed this morning in concert with a weak coastal eddy. A weak ridge aloft will bring us warm spring-like weather this entire week as we move from April to May. The jet stream will continue to our north, driving an occasional shortwave trough through the northern part of the country. For SoCal, this appears to maintain some coastal eddy circulation for much of the week, and a corresponding marine layer with varying depths and coastal cloud extent. Copy today and paste Tuesday. What you see in low cloud coverage this morning looks the same for Tuesday. Same for temperatures, which will get into the low 80s in the Inland Empire and the high desert, with 90s in the low desert. Look for seasonal onshore winds through mountain passes and locally into deserts each afternoon and evening, with top localized gusts around 45 mph. A trough to the north will help deepen our marine layer for Wednesday morning, but later Wednesday morning some upper support and offshore surface pressure gradients set up a weak offshore pattern, which lingers into Thursday. Areas through and below Cajon Pass will get some northeast wind gusts, spilling locally into the Inland Empire. Thursday has a more easterly component, favoring San Diego County foothills. Top wind gusts in these localized areas look to be around 35 mph. As you might guess, uncertainty creeps into the outlook toward the weekend. Some ensemble members, mostly from the GEFS, point to a deeper trough this weekend for cooler and breezier onshore weather. A minority of members even show precipitation Sunday. The Euro ENS members indicate less troughing, continued seasonal weather and no chance of precip. Either way, it`s nice to have truly spring- like weather. && .AVIATION... 291540Z...Coasts/Valleys...Patchy low clouds with bases 1000-1500 FT MSL across portions of coastal San Diego and Orange Counties through 17z Mon. Areas of reduced vis of 3-5 SM in CIGs. The development of a coastal eddy tonight into early Tuesday morning will lead to a slightly deeper marine layer. Bases will likely start low, similar to this morning as low clouds form between 06-09z Tue with bases between 700-1100 FT MSL, then rising to 1000-1500 FT MSL through the morning hours as the coastal eddy churns offshore. Areas of near- zero VIS/FG where low clouds intersect terrain. Tops will rise from roughly 1500 FT MSL to around 2000 FT. Otherwise, for the mountains and deserts, clear skies with unrestricted vis through Tuesday morning. && .MARINE... No hazardous marine conditions 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...Adams