009 FXUS66 KSGX 071734 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 934 AM PST Sun Nov 7 2021 .SYNOPSIS... A developing trough along the West Coast will keep the weather cool west of the mountains, with night and morning low clouds and patchy fog through Tuesday. Some drizzle is possible again early Wednesday morning, otherwise, dry weather will prevail. Winds will turn offshore during the latter half of the week, with Santa Ana conditions beginning on Thursday. Friday should be the warmest day overall, with temperatures some ten to fifteen degrees above average over the coast and valleys. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Update: Marine layer low cloudiness and inland valley patchy fog was extensive overnight, but is quickly clearing over the past hour. We expect clearing to continue into the afternoon with sunshine all areas this afternoon. Slight chance a few beaches could maintain some cloudiness. No changes were needed to the forecast this morning. See previous discussion below for more forecast details. Previous Discussion (Issued at 258 AM PST Sun Nov 7 2021): Low clouds have spread well inland early this morning, covering much of the I.E. and the valleys of San Diego County. Near the leading edge of this cloud cover, fog was reported and was locally dense. Some patchy drizzle has been reported as well. Higher clouds were visible in satellite imagery drifting NE over SE portions of the CWA. Weak to moderate onshore sfc pressure gradients were supporting better westerly winds through the passes at 15-25 MPH, with a few higher gusts. Widespread low dewpoint depressions and several reports of fog with visibility 1/4 mile or less, have prompted a Dense Fog Advisory for portions of the valleys above 800 FT. Expect gradual clearing of the low clouds and fog later this morning, with some of the higher clouds remaining through the afternoon. With the deeper marine layer, it will be a bit cooler today, and remain below average through Tuesday west of the mountains. Temperatures should be about average over the mtns/deserts. A broad trough along the West Coast will keep SoCal cool, with night and morning low clouds and patchy fog through Tuesday. On Wednesday, high pressure will begin to build off the coast, which will peak on Friday. This will initiate a warming and drying trend across the region as winds turn offshore and Santa Ana conditions develop. East to northeast winds will become gusty below the passes and along the coastal foothills, pushing the marine layer back offshore. Look for much lower humidity, and very warm afternoons, particularly along the coast and in the western valleys where temperatures are expected to be some 10-15F above average. The ridge offshore peaks in amplitude about Friday before deflating and shifting inland over the weekend. This should result in gradual cooling beginning as early as late Saturday, and continuing through early next week. && .AVIATION... 071655Z...Coast/Valleys...Low clouds with bases 800-1400 feet MSL with tops to near 2200 feet MSL will continue this morning. Vis reduced to 1-3 miles in HZ/FG in the valleys. Scatter out expected 17-19Z. Low clouds will again return after 02Z, with similar bases and inland extent. High confidence on OVC low clouds returning this evening at KSAN, and moderate-high confidence in timing in the KSAN TAF. Mountains and Deserts...SCT high clouds at/above 20,000 feet MSL and unrestricted vis expected through tonight. && .MARINE... No hazardous marine weather is expected through Thursday. && .BEACHES... High tides near 6.5 feet are expected this morning, though the tidal overflow threat is low. Tides will decrease Monday and Tuesday. && .SKYWARN... Skywarn activation is not requested. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...NONE. && $$ PUBLIC...Gregoria (Update)/Small (Previous Discussion) AVIATION/MARINE...Small