Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
557 FXUS66 KSGX 180406 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 905 PM PDT Fri May 17 2024 .SYNOPSIS... A seasonally persistent marine layer will continue for the coming week with night and morning coastal low clouds extending well inland across the valleys with limited or slow afternoon clearing for coastal areas. There will be periods of stronger, gusty westerly winds for portions of the mountains and deserts during late afternoons and nights through Monday. High temperatures will continue slightly below normal in general, although cooler early next week. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... The 3500 ft deep marine layer this morning through brought widespread drizzle and pockets of light rain to San Diego coastal and valley zones, southern Orange County and the southern Inland Empire shrank 1000 feet this afternoon and was down to 2500 feet on the 00Z NKX sounding. This is still deep enough for low clouds to spread inland and reach the mountain foothills by daybreak. At 9 PM clouds had already reached Ramona in San Diego County, but most of the Inland Empire was still clear. Weak high pressure tonight will be displaced by general troughing Saturday through Monday for a cooling trend and a steadily deepening marine layer. On Sunday night the marine layer will again be deep enough for areas of drizzle west of the mountains through Monday morning. This trough will also bring strong, gusty mountain and desert winds Sunday afternoon through Monday. From Tuesday through Friday a persistent trough over the West will bring more or less similar day-to-day weather next week with night and morning marine layer clouds west of the mountains, blustery mountain and desert winds each afternoon and evening, and temperatures that will run a few degrees below average. && .AVIATION... 180330Z...Coast/Valleys...BKN/OVC low clouds will prevail in coastal areas tonight and cover all valley locations by 06Z Sat with bases 1200-2000 ft MSL and tops to 2500-3000 ft MSL with areas of terrain obscurations. Below the clouds, local VIS will be 3-5 miles in BR. Clearing will be slow Sat, mostly 17Z-20Z in the valleys with partial clearing between 20Z Sat and 00Z Sun near the coast. Stratus will rapidly spread inland again Sat evening. Mountains/Deserts...Mostly SCT clouds will occur 06Z-17Z Sat AOA 20000 ft MSL. Otherwise, clear skies with unrestricted VIS will prevail through Sat evening. W-SW winds with gusts 25-40 kt will continue through 12Z Sat mainly on the desert mountain slopes and through/east of passes/canyons, then decrease some 12Z-20Z Sat, with areas of W-SW winds with gusts 30-45 kt after 20Z Sat, continuing Sat night. MOD UDDFS and LLWS will occur at times over/E of the mtns. && .MARINE... No hazardous marine conditions are expected through Wednesday. && .BEACHES... A series of southwest swells of 2-3 ft at 16-18 seconds from 210 degrees will build through Sunday and continue through Tuesday, producing above normal surf of 3-5 ft with locally higher sets on exposed SW facing beaches, as well as a high risk of rip currents at all beaches. Swell and surf will slowly lower around Wednesday. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...None. && $$ PUBLIC...Moede AVIATION/MARINE/BEACHES...Maxwell