Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
029 FXUS66 KSGX 112216 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 216 PM PST Tue Nov 11 2025 .SYNOPSIS... High pressure will depart the region, as a large trough moves closer to the coast into the middle of the week. An area of low pressure will move inland by Thursday through the weekend, bringing areas of rainfall, high elevation snow, and elevated winds. The chance of precipitation lowers by early next week, though the weather pattern remains active. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Current temperatures are well into the 80s to near 90 degrees for the western valleys of SD Co/Inland Empire, as well as the lower deserts. A closed low far off the coast is funneling in moisture around a high pressure axis across the region in the form of high clouds this afternoon. These high clouds will stick around as the closed low moves closer to our region by Wednesday as a large trough dramatically deepens over the East Pac off of the California coast, combining with the closed low to the south. This will bring greater onshore flow and cooling to the region with highs 10 degrees cooler in the western valleys. Highs will remain near 90 degrees again across the lower deserts on Wednesday, before becoming much cooler. By Thursday, the storm system will move closer to the region with most areas seeing another 5 degrees of cooling. Winds will be greatest on Thursday and Thursday night with widespread gusts 25-45 MPH, locally over 50 MPH in the passes. Model guidance is still struggling some with exact timing of the onset of precipitation, though hi-res models show a slower scenario with precip beginning sometime early Friday morning across the LA basin and surrounding mountains. NBM shows precip coming in as early as Thursday afternoon. Confidence becomes higher on when the heaviest precipitation will be, which will occur from north to south on Friday morning into the early afternoon. Rain rates will likely be over 0.50"/hr, locally near 0.75"/hr. As this moves through, there will be an increased risk of traffic incidents, flooding, and debris flows/mudslides from local area burn scars. Snow levels will remain rather high during this event as the system pulls in moisture from the subtropics. Snow levels will be near 9,000 feet to start on Thursday with levels dropping near 7,000 feet by Friday with a slushy accumulations under one inch in places near these levels. We continue to watch where the exact path of this area of low pressure will go as it moves inland over the weekend. This will dictate where the wrap-around moisture (the rain/snow on the north side of the low pressure system) from the weather system goes. Precip will move over the area from east to west, but confidence on where the precipitation sets up and how much falls is still in question. If the system moves further south, there will be a better chance for a greater amount of the area to get rain vs. if the low pressure center moves further north, keeping the southern half of our area not as wet. The system will exit on Sunday, leaving 20-30% chances of precip in the forecast. A secondary trough will move over the West Coast by early next week, keeping the weather pattern unsettled. The strength and how far south this system will go remains to be seen, but chances (20-30%) for light precip are in the forecast for the entire region, along with cooler weather. && .AVIATION... 112145Z...Coasts/Western Valleys...Low clouds linger along portions of the immediate coast but remain largely offshore this afternoon. These clouds will push back ashore around 02z Wednesday with bases initially near 600-800ft MSL. Bases will gradually lift overnight to 1000-1200ft by 09-12z with clouds spreading further inland. Scattering back to the coasts around 17-18z Wednesday. Otherwise...VFR conditions will continue through Wednesday with SCT-BKN high clouds AOA 20 kft. && .MARINE... A storm system will bring strong winds and elevated seas late Thursday through Friday as a front passes through the coastal waters. Wind gusts 20-25 kts expected in the outer waters, closer to 15 to 20 kts for the nearshore waters. A swath of moderate to heavy precipitation will accompany the cold front with a slight chance of thunderstorms Thursday night 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...APR AVIATION/MARINE...Munyan