360 FXUS66 KSGX 190425 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 925 PM PDT Wed Jun 18 2025 .SYNOPSIS... High pressure over the region that has aided in hot inland weather will move off to the east by Thursday and Friday. In its wake, an area of low pressure will move southward into the region. This will bring more noticeable cooler weather with breezier conditions across the mountains and deserts into the weekend and early next week. Subtle warming is expected by the middle of next week as high pressure off the coast moves closer to our area. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Update: The ridge is beginning to shift more towards the east now and allowing for the trough upstream to continue to transition ever so slowly towards the region. This will allow for an increase of winds and also a more substantial push of the onshore flow by tomorrow evening. There will also be winds increasing out of the southwest over the high deserts and increased gap flow through San Gorgonio/Banning Pass, although it still appears as if these winds should primarily remain below the threshold...despite a few localized gusts exceeding it. Temperatures will continue to cool down with the trough further deepening and moving over the region going into the weekend, especially within the Imperial Valley. The marine layer will also rise and thicken up a bit. This will be a very dry trough and likely not have any precipitation with it, although there could be some areas of drizzle possible for the coastal and inland areas by Saturday night into Sunday morning. The pattern looks to remain pretty consistent with a trough over the western states into the early part of next week, and then the overall consensus of the ensembles has the ridge beginning to flatten out towards the end of next week, with temperatures gradually warming up from Wednesday through next weekend. (Previous discussion submitted at 217 PM): A 592dm area of high pressure is currently over Arizona is providing another hot afternoon for inland areas. Current temperatures across the mountains and Inland Empire are well into the 80s and 90s with triple digit heat across the lower deserts. The marine layer is expected to deepen slightly overnight, providing a greater chance of cloud cover by morning across the coastal areas and adjacent valleys of Orange and San Diego Counties. This may also lead to foggy conditions over elevated terrain as well. A large area of low pressure off the coast of British Columbia will push southward into the weekend. Heights are expected to lower on Thursday, where temperatures will be knocked down a few degrees from today. The low will push further south into the Great Basin by Friday and Saturday, further cooling us off. Highs 5 to 10 degrees above normal today will go to 5 to 10 degrees below normal by Saturday. Confidence is high that areas west of the mountains will mainly be in the 60s near the coast, 70s in much of the valleys, with some lower 80s in the Inland Empire. The system will bring elevated wind gusts to the mountains and deserts each day, mainly near 25-40 mph, locally higher in the San Gorgonio Pass. The marine layer will significantly deepen by the weekend as well, where clouds and fog will push into much of the coastal basin each night and morning. The troughing pattern sticks around into early next week, though not as potent, which will help to weaken winds slightly. The middle of the week stays dry as weak high pressure off the coast begins to have greater influence over the area. This will bring some warming to the area, though highs do not look too far from average. && .AVIATION... 190315Z....Coast/Valleys...Satellite shows low clouds have just begun moving inland, with bases 1200-1400ft MSL and tops to 1800ft MSL. Clouds will continue to filter inland through the night, reaching KSNA likely by 06z and encroach at KONT by 11z. Bases will fall a bit, closer to 800-1100ft MSL by 08z and VIS may fall to 1- 3SM. Chances of a CIG at KONT anytime between 11z-16z are 15-25%. Clouds will clear to the coast by 17z, and potentially some clearing offshore by 19z. Low clouds develop again Thursday night and push inland after 01z with slightly higher bases. .Inland Valleys/Mountains/Deserts...Clear skies and unrestricted VIS through Thursday. && .MARINE... Northwest winds may gust close to 20 knots near San Clemente Island Friday afternoon and evening. Otherwise, no hazardous marine conditions are expected through Sunday. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...None. && $$ UPDATE...Stewey PUBLIC...APR AVIATION/MARINE...Zuber