Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
078 FXUS66 KSGX 110401 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 901 PM PDT Fri Oct 10 2025 .SYNOPSIS... A low pressure system off the West Coast will continue to draw moisture from Tropical Storm Priscilla northward into the area through Saturday morning, with chances for showers and thunderstorms at times. Cooler with drying and a return of the marine layer early next week. For Tuesday and Wednesday of next week, a low pressure system moving southward along the West Coast will bring a chance of showers along with stronger westerly winds. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Evening update... The main band of showers has shifted east towards the Colorado River Valley this evening with a few light showers lingering across San Diego County. While there were a few stronger showers and thunderstorms this afternoon, those have since dissipated. The 00Z KNKX sounding shows Precipitable Water has decreased slightly to around 1.47", most of it within the 700-500 mb layer. Water vapor imagery shows drier air beginning to push into Orange County and western Riverside/San Bernardino Counties ahead of the upper level trough just off the West Coast. As this trough progresses inland, any lingering tropical moisture and the associated light precipitation will shift eastward and out of the area by Saturday morning. Any additional accumulating precipitation tonight will be limited to a few hundredths of an inch. Patchy low clouds will develop over the coastal areas by Saturday morning, followed by seasonally warm weather with highs a couple degrees below normal. Gusty west winds will develop over the mountains and deserts Saturday afternoon and evening as trough nears and onshore pressure gradients strengthen. Gusts in the wind-prone passes and mountain slopes will peak around 35-45 mph. Previous discussion... Sunday will be slightly warmer with dry and breezy conditions. By Monday, there will be some increasing clouds as the trough continues to deepen over the eastern Pacific waters. Deterministic models have been resolving area of low pressure that deepens during the mid part of next week, and may bring about a much better chance of measurable precip, especially for the coastal/inland areas from late Tuesday through early Wednesday, as well as much colder temperatures. This will also allow for the first snowfall for some of the higher terrain, as snow levels drop below 7000 ft by Tuesday. The longwave trough might still hang around going into the latter part of next week, and may still continue to influence the region with more chances of rain and cooler temperatures, depending on the evolution of the trough (with a possibility of the upper level closed low associated with it retrograding back to the west and a secondary low emerging from it, although this is still quite far out in the forecast to be considered reliable at this time. && .AVIATION... 110300Z....SCT -SHRA continue to move across mainly San Diego County this evening and is expected to linger overnight into the early morning hours. Lower clouds are expected to develop along the coast around 11Z with bases around 1,200-1,500 ft MSL. Moderate confidence that bases will dip below 1,000 ft at KCRQ for a couple hours around 11Z. Cloud cover will decrease, with any cloud development expected to be above 20K ft MSL, by 18-21Z for most of the area. Otherwise, drier and clearer conditions expected through the rest of the TAF period for the region. && .MARINE... Northwest wind gusts occasionally exceeding 20 knots around San Clemente Island during the afternoons and evenings, highest chance on Saturday. No hazardous marine conditions are expected through Monday. Increasing winds expected by Tuesday as another weather system approaches the area. && .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...SS/Stewey AVIATION/MARINE...Villafane