Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
615 FXUS66 KSGX 052042 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 142 PM PDT Sun Oct 5 2025 .SYNOPSIS... Below normal temperatures through Monday, with a gradual warming trend into the latter part of the week. Areas of night and morning low clouds and fog will continue along the coasts and parts of the valleys through midweek. Mid and high level tropical moisture moving into the region will bring a slight chance of showers late Thursday through Saturday. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... .SHORT TERM... Satellite this afternoon showing some scattered low clouds along the south San Diego County coastline, but otherwise a mild, clear day out there. Zooming out, a large scale positively tilted trough is over much of the north-central and western U.S. A shortwave can be seen developing on the west side of the trough off the north-central California coast currently. This will develop into a little closed low late today into Monday morning as it moves down to the south- central California coast, and the weak ridge over the southern U.S. moves to cover Southern California. This will result in a gradual warm up for areas inland from the immediate coast through Tuesday, starting with inland high temperatures today that will be 2-5 degrees warmer than yesterday`s. Temperatures will still be a couple of degrees below the daily average today, despite this mild warm up. A few degrees of warming each day through Tuesday will bring temperatures closer to normal. The inversion will strengthen tonight, leading to more widespread low cloud coverage overnight. Clouds that develop this evening will still initially be quite patchy, and could remain patchy to a certain extent overnight, but will be much more uniform than previous days and make it further inland, even possibly into parts of the western and southern Inland Empire. It will also be slow to clear in the mornings, lingering along the coast possibly into the early afternoon. Similar story through mid-week. The low lifts north and opens up late Tuesday into early Wednesday, but result in little change to the local area. A very large low pressure system will drop south from the Gulf of Alaska mid- to late-week, though models have come to more of a consensus that this impacts from this will remain well to our north/northwest through early Thursday. && .LONG TERM... The potential for some more interesting weather has increased a bit for late next week into the first half of the weekend, though confidence in the details is still low as the models struggle to resolve them. Moisture advected from now Tropical Storm Priscilla will enter the area starting Thursday, and ensemble mean precipitable water peaks around 1.25-1.5" Friday. Meanwhile the large low pressure system will continue southwards, though the main impacts and lift provided from this system looks to stay to our north. As a result, showers are possible for all areas Thursday through Saturday, with chances peaking Friday at 15-30%. Just over half of global ensemble members are now showing precipitation for San Diego County, with that number decreasing a bit for areas further north. Most of the members are indicating light precipitation, with the majority of the moisture above 700 mb, and the ensemble mean is around 0.20-0.40". A few outlier solutions are very wet, as they are showing better dynamics provided from the low traveling a little further south. This latter solution would also lead to better conditions for thunderstorms. Currently the National Blend of Models is indicating a 5-10% chance for thunderstorms, locally to 15% in some of the mountains. The low opens around Saturday and then pushes eastward late Saturday into Sunday, taking the moisture with it and ending precipitation chances likely by Sunday morning. This will also lead to cooling over the weekend to below normal temperatures. && .AVIATION... 052000Z....Coasts/Valleys...Patchy FEW-BKN low clouds 1500-2000 ft MSL along the coast this afternoon. Clouds with bases 1200-1800 ft MSL will start to move inland after 00z Mon, spreading into the valleys and portions of the Inland Empire. There is a 60% chance of low clouds reaching KONT by 12Z Mon and a 30% chance of low clouds reaching KSBD. SCT conditions will return 17-19Z Mon for inland areas with the potential for lingering cigs into the afternoon along the coast. Mountains/Deserts...VFR conditions will continue through Mon. && .MARINE... No hazardous marine conditions are expected through Thursday. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...None. && $$ PUBLIC...CSP AVIATION/MARINE...CO