284 FXUS66 KSGX 100401 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 901 PM PDT Mon Jun 9 2025 .SYNOPSIS... Shallower marine layer each morning through mid-week with high temperatures 5-10 degrees above normal inland areas, peaking Tuesday and Wednesday. A slight cool down is expected for the end of the week before temperatures increase again for the weekend. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Evening update... Low clouds along the coast are slowly starting to move back inland, and elsewhere skies are clear. The 00Z KNKX sounding shows the marine inversion based near 2000 ft MSL, down about 200 ft from this morning. Low clouds will spread into the western valleys again overnight, clearing back to the coast by late morning, though beaches may once again remain cloudy through much of the day. An upper level ridge of high pressure will amplify off the coast on Tuesday and Wednesday, bringing warmer weather for the inland valleys into the deserts while the persistent, though shallower, marine layer helps moderate temperatures near the coast. The only caveat is the potential for a gulf surge into the low deserts, which may limit warming if dew points are high enough and moisture doesn`t mix out until later in the afternoon. Even then, it would be the difference between high temps of 106-108 and humid or 110+ and dry. The same holds true for Wednesday. In general, high temperatures will be around 5-10 degrees above normal both days for inland areas. Previous discussion... Late Wednesday an upper level low along the coast of Canada looks to move southward towards Graham Island, flattening the high a bit and zonal flow aloft looks to prevail over the region Thursday and Friday. Around the same time, the weaker high will slowly move eastward into Baja before reaching the Four Corners early Saturday, with ridging quickly rebuilding. A slight cool down is expected for the latter half of the week, but a return to ridging this weekend looks to push highs back to well above normal, potentially even warmer than earlier in the week. This pattern looks to holdover into early next week with no meaningful cooldown or precipitation in sight, a significant shift from just a few days ago where it seemed troughing would prevail for the weekend. && .AVIATION... 100300Z....Coast/Valleys...Low clouds currently over the beaches and nearshore waters will begin to push inland shortly filling into most of San Diego/Orange County valleys by 10z. Clouds will struggle to move into the IE with only a 60% chance of reaching KONT. Bases lowering to 500-1000 ft MSL will allow for IFR vis reductions for elevated inland areas. FG where the cloud layer intersects terrain. Scattering to the coast expected by 18-19z, but clouds may linger at the beaches and nearshore waters through the afternoon. Low clouds slowly move inland again after 00z Wednesday. Mountains/Deserts...Mostly clear skies and unrestricted VIS through Tuesday. && .MARINE... No hazardous marine conditions are expected through Friday. && .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/Zuber AVIATION/MARINE...KW