Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
781 FXUS66 KSGX 091049 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 349 AM PDT Thu May 9 2024 .SYNOPSIS... A slow warming trend will continue thorough Sunday with night and morning coastal low clouds extending well inland across most of the valleys. Slightly cooler for the coast and valleys for Monday and Tuesday, then slightly warmer for Wednesday. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... .SHORT TERM (Today through Saturday)... A slow warming trend will continue through Sunday with a coastal eddy maintaining a marine layer depth near 2500 to 3000 feet. Night and morning coastal low clouds will extended well inland across much of the valleys. With the warming, high temperatures on Saturday will be around average to as much as 5 degrees above average for the deserts and inland valleys, into the 90s for the lower deserts and upper 70s to mid 80s for the Inland Empire. && .LONG TERM (Sunday through Wednesday)... The slow warming trend will continue through Sunday with Sunday high temperatures near average at the coast to 4 to 8 degrees above average for the deserts and inland valleys, mostly in the lower to mid 80s for the Inland Empire with hottest high temperatures for the lower deserts around 100. A weak low pressure system centered over the Great Basin on Friday will move slowly eastward on Saturday and more rapidly into the plains on Sunday as another weak low pressure system develops off the California coast on Sunday. This weak low pressure system will move slowly eastward and across the southern California bight on Monday night and into northwest Mexico on Tuesday. This weak low pressure system may bring slight cooling to the coast and valleys on Monday and Tuesday and to the deserts on Tuesday. There is greater model spread on what happens to high pressure over the eastern Pacific beyond Tuesday. Cluster analysis for Wednesday shows more than 60 percent of the model variance is with the strength of high pressure near the West Coast with growing spread in the high temperature guidance for southern California for Thursday and Friday of next week. The deterministic NBM has Wednesday slightly warmer than Tuesday, then slowly cooler for Thursday and Friday. && .AVIATION... 090930Z...Coast/Valleys...Low clouds will fill most of the coastal basin into inland valleys. Bases 1600-2100 feet MSL and tops to 2700 feet. Local VIS 2-4 miles will occur in BR in the valleys, and higher terrain will be locally obscured. Valleys should clear 16- 18Z, and coastal areas 17-20Z Thu with local BKN conditions continuing thereafter near the beaches. Low clouds will push ashore and inland after 02Z with very similar bases/vis and overall coverage by Friday morning. Mountains/Deserts...Mostly clear skies with unrestricted VIS will continue today and tonight. && .MARINE... No hazardous marine conditions are expected through Monday. && .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...MM