Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
225 FXUS66 KSGX 161620 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 920 AM PDT Wed Apr 16 2025 .SYNOPSIS... Cooler, cloudier, and windier conditions expected through Friday. Periods of scattered light showers are expected tonight into Thursday morning and Thursday night into Friday. Dry and warmer conditions expected for the weekend into early next week. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Visible satellite at 9 AM was showing low clouds covering the entire coastal basin. The marine layer will stay deep through Friday, with low clouds expected to fill in the coastal basin each night. Cooler conditions are expected today and Thursday. Highs today are expected to be 5 to 12 degrees below average for areas west of the mountains with further cooling expected into Thursday. A low pressure system from the west will weaken as it moves through Southern California bringing a chance for showers for late tonight into Thursday morning for the mountains westward. Overall, rain will be light with rainfall rates 0.10 inches per hour or less. Highest accumulations will be on the coastal mountain slopes. A second low pressure system from the north will bring a chance of showers for Thursday night and Friday. Recent guidance shows a slight inland shift to the track of that system, resulting in slightly drier forecast. Latest high resolution guidance is indicating rainfall rates 0.10 inch or less as well. Through Friday evening, rainfall and liquid-equivalent above the snow level could range from less than 0.10 inch near the coast to 0.25 to 0.50 inch in the mountains, locally up to 0.75 inches. The snow level will fall to around 6500 feet on Friday with an inch or two of snowfall possible above 7000 feet. Over the mountains and into the deserts, the increased onshore pressure gradient from the passing lows will produce periods of gusty westerly winds through Friday night. Peak gusts 40 to 55 mph with isolated gusts to 65 mph are expected, most likely through passes. Strongest winds will occur Thursday, but winds will remain elevated into Friday. Dry weather is expected with warming conditions for Saturday and Sunday, continuing into early next week for inland areas while the coast and valleys may cool slightly for early next week. With the warming, high temperatures on Sunday will range from the mid to upper 60s near the coast to the mid 70s to lower 80s for the Inland Empire with the lower deserts around 90. Overall, high temperatures will mostly be within around 5 degrees of average for Saturday through Tuesday. && .AVIATION... 161600Z....Coasts/Valleys/Foothills...Low clouds fill the coastal basin into the coastal mountain slopes. Bases vary between 3000-4500 feet MSL, with tops to 4500-5500 feet, bringing vis reductions in hills where clouds intersect terrain. Patchy -DZ is possible through 17Z. Scatter out will be random/patchy and intermittent this afternoon, but with cloud bases mostly above 3000 feet MSL. Low clouds with similar bases/vis to fill the coastal basin after 02Z tonight into Thursday, again with occasional lower cigs and vis in - DZ. Higher Mountains/Deserts...SCT high clouds today and tonight. Westerly winds to gradually increase after 20Z, with strongest gusts 45-55 knots through pockets of mountain passes and into deserts. Strong up/downdrafts and isolated LLWS in lee of mountains such as vcnty KPSP. && .MARINE... No hazardous marine conditions are expected through 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...CO/17 AVIATION/MARINE...CSP/MM