Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
618 FXUS66 KSGX 011001 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 301 AM PDT Wed May 1 2024 .SYNOPSIS... The marine layer has deepened with widespread coastal low clouds extending inland across all of the valleys. The marine layer will become shallower for Thursday and Friday with night and morning coastal low clouds only extending inland across portions of the valleys. High temperatures for the coast and valleys will be a few to around 5 degrees cooler than Tuesday, then will be warmer and similar to those on Tuesday for Thursday and Friday. A low pressure system moving inland through southern California late Saturday and Sunday will bring cooling on Saturday and more significant cooling on Sunday with high temperatures for the mountains around 15 degrees below average on Sunday. There will be periods of stronger and gusty southwest to west winds for the mountains and deserts for late Saturday through Sunday. There is also a slight chance of mostly light precipitation from the coast to the mountains for late Saturday night into Sunday. Then drier and warmer for Monday and Tuesday, but with Tuesday high temperatures still below average. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... .SHORT TERM (Today through Friday)... There is a well-defined coastal eddy early this morning. The marine layer has deepened to around 3000 to 3500 feet with widespread coastal low clouds extending inland across all of the valleys and onto the lowest coastal mountain slopes. Cloud bases have also risen too, to around 2000 feet near the coast. There could be some patchy drizzle early this morning, but there have been only a few locations so far that have received 0.01 inch of precipitation in the valleys. High temperatures today will be a few degrees cooler than Tuesday with the greatest cooling in the valleys. The marine layer will become shallower for Thursday and Friday with coastal low clouds extending inland only into portions of the valleys. High temperatures on Thursday and Friday will be a few degrees warmer than today and similar to those on Tuesday, mostly a few to around 5 degrees above average. && .LONG TERM (Saturday through Tuesday)... There has been a narrowing in the model spread in both the timing and amplitude of the low pressure system moving inland through southern California for late Saturday and Sunday. The strongest onshore flow is expected for late Saturday through Sunday afternoon with gusty southwest to west winds in the mountains and deserts gradually decreasing for Sunday night into Monday. High temperatures will be a few to around 5 degrees cooler on Saturday, mostly within a few degrees of average. There will be much greater cooling on Sunday with the mountains as much as 15 degrees cooler than Saturday with high temperatures on Sunday ranging from around 5 degrees below average near the coast to around 15 degrees below average for the mountains. Chances for precipitation are greatest for late Saturday night into Sunday with 24-hour chances for measurable rainfall around 20 percent for the mountains and around 10 percent near the coast with chances for one-quarter inch or more of rainfall for the mountains around 10 percent. Monday and Tuesday are expected to be drier and warmer, but with high temperatures still below average on Tuesday. && AVIATION... 010935Z...Coasts/Valleys/Coastal Slopes...Low clouds with bases 1800- 2500 FT MSL are occurring this morning. Vis restrictions where low clouds and terrain intersect. Scatter out 15-17z Wed across inland areas and 17-19z Wed at the coast. Low clouds redeveloping at the coast and spreading inland after 01z Thu, with bases 1500-2000 FT MSL. Otherwise, clear skies with unrestricted vis through tonight. && .MARINE... No hazardous marine conditions are expected through Friday. Gusty northwest winds will develop Saturday into Sunday. && .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...EA