Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
261 FXUS66 KSGX 292036 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 136 PM PDT Mon Apr 29 2024 .SYNOPSIS... Seasonal weather is expected this week. The marine layer will keep low clouds and fog generally near the coast each night and morning, but extending into some valleys Wednesday morning. Breezy west winds will occur across mountain and adjacent deserts each afternoon and evening through Wednesday. Pockets of offshore breezes mainly in foothills and adjacent valleys should develop Wednesday and continue into Thursday. Onshore flow will help deepen the marine layer Friday through the weekend to extend coastal clouds farther inland and bring a cooling trend. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... A warm and sunny afternoon followed some coastal low clouds and fog this morning. Copy and paste this weather for Tuesday`s forecast. A weak ridge aloft will bring us seasonal 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. Temperatures 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 30-50 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 25-35 mph. As you might guess, uncertainty creeps into the outlook toward the weekend. Most ensemble members point to a deeper trough this weekend for cooler and breezier onshore weather, along with a deeper, more extensive marine layer. Many GEFS members show rain Sunday, but the Euro ENS members indicate less troughing and very little to no chance of rain. We`ll keep an eye on that currently tiny rain chance Sunday, but in the meantime enjoy the seasonal spring-like weather. && .AVIATION... 291930Z...Coasts/Valleys...Mostly clear skies with unrestricted VIS through this afternoon. 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