131 FXUS66 KSGX 082012 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 112 PM PDT Sun Jun 8 2025 .SYNOPSIS... A warming trend sets in through midweek, peaking Tuesday and Wednesday for inland and desert areas, before a very slight cooldown towards the end of the week. Above normal temperatures may return by the weekend. The marine layer becomes shallower through mid week with night and morning low clouds for the coastal areas and western valleys. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... The marine layer made it sufficiently inland this morning but continues to burn off quickly with a slightly shallower marine layer poised to push inland again tonight, persisting through at least mid week. Water vapor imagery currently shows an upper level low moving into Central California while high pressure amplifies off the coast of Baja. As the low moves into California today, it becomes an open trough and sweeps down into western Arizona on Monday, limiting the influence of the ridge to the southwest. As such, high temperatures on Monday look similar to highs today, with only slight warming by a degree or two for the deserts and Coachella Valley. Tuesday through Thursday, the ridge shifts slightly northeast and a quick warm up ensues for nearly all locations east of the coasts. One noticeable change in the models compared to previous runs is the indication of some gulf moisture trying to sneak up into the deserts and Coachella Valley on Tuesday and moreso on Wednesday, which would severely limit the warming potential there. Should this occur, highs in the low deserts and Coachella valley may be cooler by around 3-7 degrees compared to the current forecasted highs for both Tuesday and Wednesday. At this point, chances of exceeding 105F in the Coachella Valley on Tuesday are around 70% while the chance for exceeding 110F is around 40%. Elsewhere, the shift of the high to the north has encouraged significant heating over the previous forecast, with highs for many spots in the Inland Empire now expected to be well over 90F, with around a 60% chance of hitting or exceeding 95F both Tuesday and Wednesday for locations like San Bernardino and Hemet. For the coastal regions, a shallower marine layer would support a slightly quicker burn off and warmer afternoons, but at this point the moderate onshore flow looks to help it persist along the direct coast through at least mid week, helping hold temperatures near normal for mid June while other locations heat up. There is still strong agreement between the global models with an upper low transversing south along the Canadian coastline, breaking down the ridge and zonal flow aloft settles in over the region. Newest guidance slows down this low and shifts the high into Baja late week and eventually into the Four Corners this weekend, with weak ridging over SoCal for the end of the week and stronger ridging for the weekend. Currently, ensemble members support this pattern compared to the more aggressive troughing, and this would prevent much cooling off for inland areas and the deserts through the end of the week. Should this pan out, there may be more stagnant temperatures or only a slight cooldown into the end of the week with a quick warm up this weekend. There remains a lot of uncertainty with the placement of the high as well as the Canadian low, but have generally adjusted temperatures to match this warmer solution in the long term. && .AVIATION... 082000Z....Coast/Valleys...OVC low clouds with bases 1200-2000 ft MSL will linger along the immediate coast through the afternoon with only partial and intermittent clearing. Clear skies will prevail in the valleys. Low clouds slowly push inland again after 00z Mon. Patchy cig coverage expected to reach portions of the Inland Empire 09-12Z Mon. Bases tonight into Mon AM are expected to be 500-1200 ft MSL, with vis restrictions 2-4 SM in patchy FG for elevated inland valleys. Low clouds expected to clear to the coast 16-18Z Mon, with partial and intermittent clearing expected again along the immediate coast Mon afternoon. Mountains/Deserts...Mostly clear skies and unrestricted VIS through Monday. && .MARINE... No hazardous marine conditions are expected through Friday. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...None. && $$ PUBLIC...Zuber AVIATION/MARINE...CO