Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
854 FXUS66 KSGX 160959 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 259 AM PDT Wed Jul 16 2025 .SYNOPSIS... A weak low pressure system from the south will bring an increase in mostly mid level monsoonal moisture on Thursday and Friday with a chance for mainly afternoon showers and thunderstorms, mainly for the mountains. The chances are greatest for the San Bernardino Mountains. Then drier for the weekend into the middle of next week. Thursday will be cooler for the deserts, but with an overall slight warming trend for most areas through Wednesday of next week with high temperatures warming a few degrees. Night and morning coastal low clouds will continue to spread into portions of the western valleys late each night. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... .SHORT TERM (Today through Friday)... A weak low pressure system from the south will bring an increase in mid level monsoonal moisture on Thursday and Friday with ECMWF ensemble output showing the peak in precipitable water values late Thursday afternoon. This will bring a chance for mainly afternoon showers and thunderstorms on Thursday and Friday, mainly for the mountains. The greatest chances are over the San Bernardino Mountains. NBM chances for measurable rainfall for Big Bear have increased to around 40 percent on Thursday and 35 percent on Friday. However, chances for one-quarter inch or more of rainfall have remained around 10 percent each day with chances for one-half inch or more of rainfall less than 5 percent. The marine layer will remain around 2000 feet deep with night and morning coastal low clouds spreading into the western valleys late each night. There will be slight day to day changes in high temperatures through Friday with the deserts a few degrees cooler on Thursday. && .LONG TERM (Saturday through Tuesday)... There will be a drying trend for the weekend into early next week with an overall slight warming trend in high temperatures of a few degrees from today through Wednesday of next week. Not much change with the marine layer with night and morning coastal low clouds spreading into portions of the western valleys late each night. High temperatures for Wednesday of next week will range from around average for the deserts to as much as 5 to 10 degrees below average for portions of the valleys. High temperatures for Wednesday of next week will range from the lower 70s near the coast to the mid 80s to mid 90s for the Inland Empire with 106 to 110 for the lower deserts. && .AVIATION... 160915Z....Coast/Valleys...Low clouds based 1400-1800 ft MSL will continue to move inland to 25-30 miles from shore, with a 75% chance KONT sees CIGs between 11-16z and KSBD having a 30% chance during this time frame. Clouds scatter 15-17Z inland and 17-19Z for coastal areas, with areas of clouds remaining along parts of the immediate coast all day, particularly in San Diego County. Clouds with similar bases reform and push back inland after 17/00Z. Mountains/Deserts...Mostly clear skies with unrestricted VIS through this morning. Increasing clouds above 15000 feet MSL today, with cumulus near 10000 feet possible 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 today 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...17 AVIATION/MARINE/BEACHES...CSP