Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
315 FXUS66 KSGX 160418 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 918 PM PDT Tue Jul 15 2025 .SYNOPSIS... High pressure will continue to weaken as an upper level low pressure system off the central coast of Baja moves into northern Baja Thursday night and into southern California on Friday. There will be cooling for today and Wednesday with a chance of afternoon showers and thunderstorms, mainly for the mountains on Thursday and Friday, with decreasing chances on Saturday afternoon. Then drier and a little warmer inland for Sunday into early next week. Night and morning coastal low clouds will spread into the western valleys late each night. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... This evening...The marine layer remains at about the same depth as this time yesterday and low clouds are increasing in coverage and spreading inland. The low clouds will once again likely spread 15-20 miles inland by sunrise. High temperatures this afternoon were near or several degrees below seasonal averages. From previous discussion... Through Thursday... High pressure will further weaken across southern California while a low pressure system centered just off the coast of central Baja moves into northern Baja late Thursday. There will be cooling for Wednesday with the greatest cooling in the mountains and a few degrees of cooling for most areas on Thursday. Monsoonal moisture will increase on Thursday with a slight chance of showers and thunderstorms on Thursday afternoon, mainly for the mountains. The marine layer will remain around 2000 feet deep with night and morning coastal low clouds spreading into the western valleys late each night. Friday through Monday...The center of upper level low pressure will move northward into the vicinity of southern California on Friday. NBM chances for afternoon thunder and measurable rainfall are greater on Friday than Thursday and greatest for the San Bernardino Mountains on both days. Convection on Friday afternoon will not necessarily be tied to terrain with some elevated convection on the north side of the upper low moving toward the west and southwest in the circulation around the upper low. However, just where that might occur in southern California on Friday afternoon is less certain given the spread in the track of the center of the upper low. Moisture will be decreasing for Saturday and Sunday with lesser chances for afternoon showers or thunderstorms on Saturday and mostly for the mountains with a less than 10 percent chance for any showers and thunderstorms for the mountains on Sunday afternoon. Drying will continue into early next week with not much change in high temperatures for the coast and valleys with the deserts a few to around 5 degrees warmer. && .AVIATION... 160345Z....Coast/Valleys...Low clouds have been gradually filling in over the immediate coast over the last hour or so. These clouds (generally based 1400-1800ft MSL) will continue to push inland through the next several hours, eventually pushing into the Inland Empire 09-12z Wednesday. 75% chance KONT sees CIGs between 11-16z Wednesday with KSBD having a 30% chance during this time frame. Clouds begin to scatter for inland areas by 15-16z, but could take until 17-19z along the coast. As seen the last few days, a few locations along the coast (particularly in San Diego County) could see patches of clouds linger into the afternoon. Mountains/Deserts...Mostly clear skies with unrestricted VIS through early Wednesday. Increasing clouds above 15000 feet MSL Wednesday, with cumulus near 10000 feet forming over the mountains 18-01z. && .MARINE... No hazardous marine conditions are expected through Sunday. && .BEACHES... A moderate period south-southwesterly swell (2-3 feet at 15-16 seconds) will generate elevated surf and a high risk of rip currents Wednesday and Thursday. Surf of 3-5 feet expected with sets to 6 feet possible, primarily on southerly facing beaches. Swell and surf will begin to lower on Friday. && .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...PG AVIATION/MARINE/BEACHES...Munyan