120 FXUS66 KSGX 080401 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 901 PM PDT Sat Jun 7 2025 .SYNOPSIS... The warming trend continues through midweek, peaking Monday and Tuesday, before a slow cooldown towards the end of the week. The marine layer becomes shallower through mid week, but may persist for the coastal areas with low clouds and fog during the nights and mornings. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Thais evening...The marine layer is several hundred feet shallower than at this time yesterday. There is also significantly less low cloud cover, with only the San Diego County coastal areas and valleys covered by low clouds. Elsewhere, skies are clear. High- resolution models do still show a return of widespread low clouds west of the mtns tonight but with a shallower marine layer, we are less likely to see the same pattern of drizzle that we saw the last couple of nights. From previous discussion... A warming and drying trend sets in through mid week as upper level ridging builds in over California. The thermal ridge axis will extend from the Desert Southwest up into the Columbia Basin on Tuesday, pivoting to southeastern California through Utah on Wednesday. Subsidence squishes the marine layer and allows temperatures to quickly warm across the deserts and Coachella Valley both Tuesday and Wednesday, with a 85% chance of >105F in the low deserts and Coachella Valley and a 40% chance of >110F, highs around 5-10 degrees above normal for mid June. Even areas further west will see a significant warm up, with 90s in the Inland Empire and upper 80s to low 90s in the San Diego valleys by Tuesday. For coastal areas, moderate onshore flow along with the shallow but persistent marine layer should limit significant warming with temperatures near or just slightly above normal Tuesday and Wednesday. Flow aloft turns more zonal as an approaching trough from the coast of OR moves inland Thursday. This will mark the transition back to average temperatures/cooler weather for SoCal and a deeper marine layer as numerous shortwaves move across NorCal through Saturday. While models differ slightly with the position of a somewhat stationary upper level low off the coast of Canada this weekend, troughing looks to persist over California through at least the weekend and potentially into early next week. && .AVIATION... 080330Z....Coast/Valleys...The marine layer managed to clear out of Orange County and northern San Diego County this afternoon/evening, but BKN-OVC clouds based around 1000-1500ft MSL still persist over southern San Diego County. These clouds have already begun to nudge back inland over the last hour or so, and this trend will continue with clouds filling back in through the coastal mountain slopes, northward across Orange County, and eventually the Inland Empire by around 09-11z Sunday. Bases look to lower some overnight, falling closer to 600-1200ft MSL with VIS reductions 3-5 SM in the valleys and near higher coastal terrain. Low clouds should clear for the inland areas through 16-18z Sunday, with partial and intermittent clearing along the coast Sunday afternoon, especially for Orange County and into northern San Diego County as was seen today. Mountains/Deserts...Mostly clear skies and unrestricted VIS through Sunday evening. && .MARINE... No hazardous marine conditions are expected through Thursday. && .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...PG AVIATION/MARINE...Munyan