Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
628 FXUS66 KSGX 182034 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 134 PM PDT Fri Apr 18 2025 .SYNOPSIS... Hit-and-miss showers continue through this evening, most likely over the mountains, parts of the high desert, and southern San Diego County. After a cloudy, cool, and breezy day today, dry and warmer conditions are on tap for the weekend into early next week, with high temperatures near to around 5 degrees above average by Monday. Gradual cooling follows Tuesday through Friday. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... .SHORT TERM...Today (Fri 18) through Sun 20... A large scale upper level low is over the western U.S. today, bringing cloudy, cool, and breezy weather. Radar this afternoon shows a few small showers moving eastwards across southern San Diego from the coast to the mountains. Mostly cloudy skies through most of the region mountains westwards will continue through late this evening, with only partial, intermittent clearing this afternoon, mostly for northern coastal areas. As the upper low pressure continues to move into the desert southwest late this afternoon and evening, isolated showers will develop over the mountains and northeast high desert, with slight chances for eastern inland valleys and western foothills as well, while showers along the coast taper off. Additional rainfall totals for the rest of today will be on the lighter side, 0.05" to locally 0.25", and snow from a trace up to half an inch will be limited to mountains above 7000 to 7500 feet. The low will also keep west to southwest winds on the gusty side over the mountains and deserts today, and maximum wind gusts will peak at 30 to 45 mph late this afternoon through the mountain passes. Winds weaken late this evening. Showers, where present, end late tonight, and skies will mostly clear overnight as a weak ridge starts to build in. Mostly clear skies with warmer high temperatures near normal for the coastal areas and up to 5 degrees below for inland areas follow Saturday. Seasonally average afternoon breezes are expected, with a stronger sea breeze than previous days. Some patchy low clouds will develop near the coast overnight Saturday into Sunday, but mostly clear skies will predominate for most areas. && .LONG TERM... Temperatures will continue to increase Sunday and Monday, and high temperatures will be near normal for coastal regions and about 5 degrees above average for inland areas by Monday. Coastal areas cool off slightly Tuesday, and the cooling trend spreads inland Wednesday through Friday, with overnight and morning low clouds and patchy fog that will gradually get slightly deeper and further inland towards mid-week. Afternoon high temperatures will be back to 5-10 degrees below average for this time of year by the late week. Ensemble weather models are in good agreement through late Saturday, with differences in the placement of an upper low pressure after that. A minority of model outputs indicate precipitation around Sunday-Monday, while the majority keep us dry if cooler than average. && .AVIATION... 182000Z....Coasts/Valleys/Foothills...Multiple cloud layers with SCT to locally BKN clouds 1500-3000 feet MSL, and a BKN-OVC cloud layer at 5000-8000 ft MSL. ISO -SHRA possible through 22Z for the valleys and 00Z Sat for the mountain foothills. Higher terrain will be obscured in FG up to 8000 feet. Partial scatter out likely for the coast and valleys through the afternoon, with a gradual clearing overnight into Saturday. Higher Mountains/Deserts...Areas of high clouds across the High Desert through 00Z, with clear skies elsewhere. Westerly winds with gusts 25-35 kt, locally up to 45 kt through and below passes will continue through 00Z Sat. Strong up/downdrafts and isolated LLWS in lee of mountains such as vcnty KPSP. && .MARINE... No hazardous marine conditions are expected through Tuesday. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...None. && $$ PUBLIC...CSP AVIATION/MARINE...CO