Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
977 FXUS66 KSGX 240352 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 852 PM 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... .Evening Update... Onshore flow continues at this hour, with some mountain passes seeing wind gusts 40-60 MPH, mainly through the San Gorgonio Pass. Winds will briefly drop off through the morning, before ramping back up by Friday afternoon. As the trough progresses through the area, winds will become more widespread into the deserts. There is a low to moderate chance in seeing wind gusts over 45 MPH in the deserts per latest HRRR and NBM model runs this evening. Low clouds will continue to fill in the coastal basin through the nighttime hours. HREF gives most areas a low chance in 50%+ sky cover Friday afternoon, though with a deepening marine layer throughout the day, clearing may be short lived near the coast. Otherwise, minimal forecast changes through the cooler weekend and warmer parts of next week. .Previous Discussion (140 PM Thursday)... 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... 240400Z...Coast/Valleys/Foothills...BKN/OVC low clouds will continue to spread overnight, reaching all areas by 11Z Fri with bases 1800- 2500 ft MSL and tops 2500-4000 ft MSL. Higher terrain will be obscured but most VIS below the cloud bases will be 6+ miles. Slow clearing will occur Fri with valley partially clearing 17Z-21Z Fri with the coast partially clearing 18Z-22Z Fri, though bases will generally rise to 2700-3700 ft MSL Fri in areas that remain cloudy Fri afternoon. Stratus will become widespread again Fri evening. Mountains/Deserts...Clear skies with mostly unrestricted VIS will continue through Fri evening. Areas of winds from the west with surface gusts 25-45 knots will occur at times through Fri evening from the mountain crests east/north through the desert slopes and into the deserts, including near San Gorgonio Pass. Strongest winds will be after 00Z Sat. Local blowing dust could reduce VIS to 3-5 miles after 21Z Fri. && .MARINE... West to northwest winds will gust near or slightly over 20 knots in the outer coastal waters (30-60 NM from the coast) 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...APR/PG AVIATION/MARINE...Maxwell