155 FXUS66 KSGX 162037 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 137 PM 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 morning. 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... At 1 PM visible satellite was showing low clouds clearing from the coast, with a stubborn low cloud deck lingering from the valleys to the mountain slopes. The marine layer will stay deep through Friday, with widespread low cloud coverage across the coastal basin each night. Below average temperatures will continue Thursday with highs in the inland valleys 10 to 15 degrees below average. 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. A second low pressure system from the north will follow Thursday night into Friday bringing additional chances of showers. Recent guidance shows a slight inland shift to the track of that system, resulting in slightly drier forecast. Overall, rain will be light with rainfall rates 0.10 inches per hour or less for both passing systems. 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 southwest to west 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 the weekend into early next week for the mountains and deserts. Coast and valley locations will remain dry but may cool a degree or two 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... 162000Z....Coasts/Valleys/Foothills...Clouds based 4000-5500 ft MSL with tops to about 6500 ft are present through the coastal basin into the coastal mountain slopes. Very patchy, intermittent clearing is possible through late this afternoon. Low clouds will again fill the coastal basin and lower to 3000-4000 ft MSL this evening after 02Z. -SHRA will move into the region from the coast eastwards after 05Z Thu, bringing locally lower vis and cigs to 2500 ft MSL, before becoming isolated to the coastal foothill after 16Z Thu as cloud bases rise again to 3500-5000 ft MSL. Higher Mountains/Deserts...FEW-SCT high clouds today and tonight. Westerly winds to gradually increase this afternoon and evening, with strongest gusts 45-55 knots through pockets of mountain passes and into deserts through Thur. Strong up/downdrafts and isolated LLWS in lee of mountains such as vcnty KPSP. && .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...CO AVIATION/MARINE...CSP