Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
633 FXUS66 KSGX 231545 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 845 AM PDT Thu May 23 2024 .SYNOPSIS... Cooling through Saturday with gusty southwest to west winds in the mountains and deserts. The strongest gusts are more likely on Friday afternoon into Friday night. Night and morning coastal low clouds will extend inland across all of the valleys and onto the lower coastal slopes of the mountains with slower daytime clearing for coastal areas. High pressure to the south will bring warming for Sunday through Wednesday. The marine layer will become shallower with night and morning coastal low clouds only extending inland into portions of the valleys by the middle of next week. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... This morning, the sounding and aircraft reports show the marine layer at about 4000 ft deep, with low clouds covering the area from the coast to the coastal mtn slopes and extending up the Cajon Pass. We remain under broad cyclonic flow aloft, with a coastal eddy in place. The inversion strength is similar to yesterday but the saturated layer is a little thicker which could make for slower clearing and lingering clouds at the coast into the afternoon. From previous discussion... A low/trough embedded in the mean cyclonic flow over the western U.S. will move inland to our north tonight and Friday and will bring stronger onshore flow. The marine layer will deepen, cooling will spread inland, and there will be periods of gusty southwest to west winds for the mountains and deserts with the strongest winds for Friday afternoon into Friday night. The additional deepening of the marine layer to 4500-5000 feet Friday night into Saturday morning could bring patchy drizzle at lower elevations west of the mtns. There will be gusty southwest to west winds in the mountains and deserts, with the stronger winds on Friday and Saturday. The winds will peak Friday afternoon into Friday night with gusts mostly 40 to 50 mph except in the northern Coachella Valley below the San Gorgonio Pass where winds could gust to around 60 mph. High temperatures today will cool a few degrees from those on Wednesday. There will be further cooling on Friday. The deserts will continue to cool slightly on Saturday while the coast and valleys warm slightly. With the cooling, high temperatures for the mountains and inland valleys will be as much as 10 to 15 degrees below seasonal averages on Friday. For Sunday through Wednesday... Building high pressure to the south will compete for dominance with the low/trough to our north and could bring warming through the middle of next week. The greatest warming is expected for Sunday and Monday with slight additional warming for Tuesday and Wednesday. With the warming, high temperatures on Wednesday will be around average for the coast and valleys and around 5 degrees above average for the deserts, mostly in the 80s for the Inland Empire and the upper 90s to 104 for the lower deserts. The marine layer will gradually decrease in depth with night and morning coastal low clouds only extending inland into portions of the valleys by the middle of next week. && .AVIATION... 231430Z...Coast/Valleys/Foothills...Low clouds with bases 2500-2900 FT MSL extend through the foothills this morning. Locally reduced vis where low clouds and terrain intersect. A coastal eddy is setting up which will limit the ability for areas near the coast to scatter out. Some scattering out across inland areas around 18-21z Thu. Low clouds progressing back inland after 23z Thu with similar bases. Mountains/Deserts...Clear skies with unrestricted VIS through tonight. W-NW wind gusts of 20-35 kt over/east of mtns after 00z Fri, with weak-mod up/downdrafts and LLWS over/east of the mtns. && .MARINE... Northwest winds are expected to gust near 20 knots in the outer waters each afternoon and evening Friday through Sunday. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...Wind Advisory from noon Friday to 2 AM PDT Saturday for San Gorgonio Pass Near Banning. PZ...None. && $$ PUBLIC...PG AVIATION/MARINE...Suk