Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
193 FXUS66 KSGX 072032 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 132 PM PDT Fri Jun 7 2024 .SYNOPSIS... There will be a slow cooling trend through Sunday. Minor fluctuations in daily temperatures and marine layer depth then follow for much of next week. The marine layer will mostly fluctuate between 2000 and 2500 feet deep, keeping coastal areas cooler with night and morning coastal low clouds extending inland into portions of the valleys. There will also be slightly stronger onshore flow this weekend, with gusty southwest to west winds for the mountains and deserts each late afternoon and evening. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Low clouds continue to linger over and near the immediate coast as of 1 PM PDT this afternoon. The 12z Miramar sounding indicated a roughly 9-10C low-level inversion along with a saturated layer from near the surface to roughly 2000 FT MSL, likely the main culprits for the slow clearing yet again today. An upper level low is also sitting off the southern Baja coast, acting to send some high-level clouds into the deserts of SoCal. High pressure over the western US will weaken through the weekend and the current Baja low will open up into a wave and move inland, while another low pressure system forms offshore. There will accordingly be a slight and gradual cooling trend this weekend, generally on the order of 2-5 degrees each day for most locations. Highs will flip to being several degrees cooler than seasonal normal for areas west of the mountains, while the deserts slowly fall back to seasonal average by Sunday and Monday. Marine layer clouds will cover much of the coastal basin well into the late mornings and afternoons (location dependent) each day through the weekend. The developing low off the SoCal/northern Baja coast this weekend will maintain onshore flow through next week, which will support a deep marine layer each day and will also lead to gusty winds over the mountains and deserts each afternoon and evening. The strongest gusts are expected in the northern Coachella Valley below the San Gorgonio Pass, with gusts to around 45-55 mph. Wind gusts of 30-40 mph can be expected elsewhere for the desert mountain foothills. The weak upper low off the SoCal/northern Baja coast then looks to remain in place for much of next week as a blocking pattern sets up over the Eastern Pacific/NW Mexico, perhaps eventually opening up into a wave and moving inland sometime around Thursday or Friday of next week. Very minor fluctuations in temperatures and marine layer depth is expected during this time, so an abundance of June Gloom and slightly cooler temperatures look likely for next week. && .AVIATION... 071935Z...Coast/Valleys...Low clouds cover most of the coastal areas this afternoon, with CIGs at coastal TAF sites. Bases are 900 to 1100 ft MSL with tops to 2000 ft MSL. Low clouds will spread inland again after 00Z with slightly higher bases and tops, filling the coastal basin by 13Z Saturday. Higher terrain obscured with VIS 1- 3SM in fog where clouds and terrain intersect. Expect inland clearing 16Z-18Z Sat and partial clearing at the coast 18Z-21Z Sat. Elsewhere...FEW-SCT250 and unrestricted VIS through Saturday. && .MARINE... No hazardous marine conditions are expected through Tuesday. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...Excessive Heat Warning until 9 PM PDT this evening for Apple and Lucerne Valleys-Coachella Valley-San Diego County Deserts- San Gorgonio Pass Near Banning. PZ...None. && $$ PUBLIC...Adams AVIATION/MARINE...PG