Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
277 FXUS66 KSGX 220404 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 904 PM PDT Tue May 21 2024 .SYNOPSIS... A slight warming trend through Wednesday, followed by a cooling trend Thursday through Saturday with a deeper marine layer and more low cloud coverage. There will also be stronger and gusty southwest to west winds for the mountains and deserts. High pressure then brings a warming trend for Sunday into the middle of next week with the marine layer becoming gradually shallower. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... .Evening Update... For what feels like the first time in a long time, skies are mostly clear this evening aside from a little patch of low clouds near Carlsbad and Oceanside. The 00Z KNKX sounding shows the marine inversion based near 2300 ft MSL, down from 2600 ft MSL this morning. Low clouds will gradually develop tonight and spread into portions of the valley, though not as widespread as last night. With the return of onshore flow don`t expect to see the random early clearing tomorrow, but most areas should still clear by late morning with the exception of the beaches. Otherwise warmer inland Wednesday with highs remaining several degrees below normal for the mountains westward. .Previous Discussion... For Thursday into the weekend, troughing at 500mb will expand over the Southwestern US. This will enhance the onshore flow again, with a coastal eddy also forming Thursday and Friday. Ultimately this means more marine layer coverage across much of the coasts and inland valleys, lasting later into the mornings and afternoons from Thursday through the weekend. Clearing at the coast may be very slow and ultimately limited in spots Friday and Saturday. Temperatures will also steadily cool again during this time, ultimately topping out nearly 5 to 10 degrees cooler than seasonal normals at the coast and 10 to 15 degrees cooler than normal in the valleys and mountains. Sunday and Monday will see troughing weaken and eventually give way to ridging at 500mb, leading to a steady warming trend early next week. The marine layer will also become more shallow during this time, and steadily begin to clear out earlier each day. There will still be some degree of morning cloud cover across the coasts and valleys each day. Temperatures will rebound to near seasonal average by next Tuesday in the coasts and valleys, while the deserts begin to see triple digit highs reappear if not by Monday, then likely by Tuesday of next week. && .AVIATION... 220345Z...Coast/Valleys/Foothills...Low clouds will continue to push inland and fill the coastal basin overnight into Wednesday. Bases would be 1500-2000 feet MSL with more vis restrictions across the Inland Empire and some coastal mountain foothill areas. Mountains/Deserts...Clear skies with unrestricted VIS will continue today and tonight. W-NW winds increasing again Wednesday afternoon and evening with peak wind gusts of 20-30 kts expected. && .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...SS AVIATION/MARINE...Suk