Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
984 FXUS66 KSGX 171054 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 354 AM PDT Fri May 17 2024 .SYNOPSIS... A seasonally persistent marine layer will continue into next week with night and morning coastal low clouds extending well inland across most of the valleys with limited or slow afternoon clearing for coastal areas. There will be periods of stronger and gusty southwest to west winds for the mountains and deserts each late afternoon through late evening through Monday with the stronger gusts to 35 to 45 mph with isolated stronger gusts. Slight changes in high temperatures through Saturday, cooling for Sunday and Monday, then warmer for next Tuesday and Wednesday. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... .SHORT TERM (Today through Sunday)... The marine layer remains around 4000 feet deep with coastal low clouds extending well inland across all of the valleys and onto the lower coastal mountain slopes. Satellite imagery shows the low clouds and fog extending all of the way through the Cajon Pass. Cloud bases across the coast and valleys in San Diego County have lowered with a resulting deeper saturated layer. There has been patchy drizzle overnight for the coast and valleys in San Diego County into southern Orange County with measurable amounts of a few hundredths of an inch or less. The deep marine layer will continue through the weekend with night and morning coastal low clouds extending well inland across all of the valleys with slow or limited afternoon clearing for coastal areas. Minor day to day differences for high temperatures for the coast and valleys through Saturday with slight cooling for the deserts. This will be followed by a few degrees of cooling for most areas on Sunday. There will also be periods of gusty southwest to west winds for the mountains and deserts each late afternoon through late evening with the stronger gusts to 35 to 45 mph and isolated gusts to 55 mph in the northern Coachella Valley below the San Gorgonio Pass. && .LONG TERM (Monday through Thursday)... On Monday, a low pressure system from the north will move through the Great Basin while a weak low pressure system over the eastern Pacific moves inland through northern Baja. Low pressure will then weaken across the area through the middle of next week. The cooling trend will continue through Monday with Monday high temperatures around 5 degrees below average at lower elevations to around 8 to 12 degrees below average for the mountains and inland valleys, mostly 60s and lower 70s for the coast and valleys and only into the lower 90s for the lower deserts. It will be warmer for Tuesday and Wednesday with Wednesday high temperatures around average for the deserts and a few degrees below average for the coast and valleys. While the marine layer may be a little shallower for the middle of next week, night and morning coastal low clouds will still extend well inland across most of the valleys. && .AVIATION... 170845Z...Coast/Valleys...Stratus with bases 1200-2500 ft MSL, highest to the north, and tops to 3100 ft MSL continuing through the morning, obscuring lower coastal slopes of the mountains. Isolated CIGS below 1000 ft MSL and vis 4-6 SM in BR/DZ through 16Z. Low clouds clearing inland 16-19Z with partial clearing along the coast 19-21Z. Low clouds redeveloping at the coast 18/00-03Z and spreading into the inland valleys overnight with bases near 1000-1500 ft MSL and tops to 2500 ft MSL. Mountains/Deserts...Mostly clear with unrestricted VIS through Saturday morning. West winds gusting 25-35 kt through mountain passes into adjacent deserts through about 14Z. West winds redevelop around 22Z and continue through Sat morning with surface gusts 30-40 kt below the passes. MOD up/downdrafts and LLWS possible over and E of the mountains. && .MARINE... No hazardous marine conditions through Tuesday. && .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...17 AVIATION/MARINE...SS