091 FXUS66 KSGX 260406 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 906 PM PDT Fri Jul 25 2025 .SYNOPSIS... A trough of low pressure will continue cooler than normal weather through the weekend. High pressure will have greater influence on the area from the east, leading to near average temperatures by next week. Breezy west winds will continue this weekend across mountains and deserts, while the marine layer covers areas west of the mountains with low clouds each evening into the morning hours. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Evening update... Marine layer low clouds have redeveloped along the coast with clear skies elsewhere. The marine layer inversion was based near 1900 ft MSL on the 00Z KNKX sounding, down from about 2300 ft MSL this morning. A weak trough moving inland across California into Saturday will help deepen the marine layer with low clouds spreading into the inland valleys by sunrise Saturday. Otherwise breezy west winds will continue in the mountains and deserts through late tonight, then strengthening again Saturday afternoon and evening. Wind gusts will generally be around 25-35 mph, locally around 50 mph through the San Gorgonio Pass. High temperatures Saturday will be as much as 10-15 degrees below normal away from the coast, and around 4-7 degrees below normal near the coast. Even the inland valleys will barely reach the mid 80s. Only other thing to note this evening is that ensembles have dried out for the middle to latter part of next week, with only a few members of each global ensemble showing an uptick in precipitable water. At this point chances of monsoon moisture returning are extremely minimal with southwest flow aloft dominating the pattern. Previous discussion... The low will weaken and combine with the mean flow aloft by Sunday and Monday as a large area of low pressure moves closer to the Pacific Northwest. As this occurs, high pressure over the Southern Plains of Texas will expand westward into the Desert Southwest. This will bring a warming trend to our region by the early part of next week. By Tuesday into the latter part of next week, temperatures will plateau near average across the region. Widespread 90s will return to the Inland Empire/High Desert, near 110 degrees in the lower deserts, with 70s/80s for the mountains, coastal valleys and beaches. Ensemble models show the weak troughing pattern continuing into later next week keeping temperatures near normal. Model differences become more apparent by the following weekend, some showing higher pressure moving into the area which would lead to a slow warming trend. && .AVIATION... 260300Z....Coasts/Valleys...Low clouds based at 1500-2000 feet MSL will move ashore this evening and inland overnight, eventually filling most of the coastal basin. Areas of reduced vis 1-5SM in the inland valleys. Low clouds to scatter out Saturday 15-18Z. Low clouds Saturday evening should develop a little later (after 04Z) and a little lower (1000-1500 feet MSL) and not extend as far inland Sunday morning. Mountains/Deserts...Mostly clear with VFR conditions through Saturday. && .MARINE... No hazardous marine conditions are expected through Wednesday. && .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/APR AVIATION/MARINE...MM