Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
620 FXUS66 KSGX 132117 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 217 PM PDT Sun Jul 13 2025 .SYNOPSIS... A little warmer inland for today and Monday. Gradual cooling back to near seasonal averages expected for the middle to the end of the week. While chances are still low and uncertainty remains, confidence is increasing for the potential of monsoonal thunderstorms over the mountains late in the week. Marine layer low clouds and patchy fog will spread across the coastal areas and into the western valleys during the nights and mornings. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... This morning...The marine layer is about the same depth as at this time yesterday and the low clouds are similar in coverage. Clearing may be a little faster today than yesterday as the marine layer inversion seems to be a little weaker. The dominant ridge will remain centered about 135 miles west southwest of San Diego through Monday. This will allow inland temperatures to rise by a few degrees above what they were the last couple of days. Temperatures in the mtns and deserts will be several degrees above seasonal averages while west of the mtns, temperatures will be near or a few degrees below seasonal averages. This is mostly due to a relatively shallow but persistent marine layer, with low clouds and patchy fog in the coastal areas and western portions of the inland valleys each night and morning. On Monday, a couple of inverted troughs in the southeast flow on the southern side of the east-west oriented ridge axis will bring some monsoonal moisture into SoCal but the threat of afternoon convection will be low because the moisture will be limited and mostly above 10,000 ft, although a stray shower or tstm can`t be ruled out altogether. For Tuesday through the end of the week, model solutions begin to diverge significantly introducing more uncertainty into the forecast but in general, the dominant high pressure ridge will be weakened and displaced eastward towards the Four Corners as a low pressure system moves inland over the Pacific Northwest. During this time, temperatures will begin to trend generally lower even as conditions become drier for Tue and Wed. For Thursday through the weekend, an increasing number of solutions across model platforms are indicating an increase in monsoonal moisture with a corresponding increase in the chances for afternoon showers and tstms, mainly in the mountains. This change in the pattern will likely continue the trend toward lower temperatures for the mtns and deserts. && .AVIATION... 132030Z....Coast/Valleys...Low clouds have cleared out nicely this afternoon, with only a few isolated patches in a couple spots along the coasts. VFR prevails throughout the day until low clouds redevelop and push back ashore around 02-04z Monday. Bases may lower some overnight, but should generally range around 900-1300ft MSL with about 10-15 miles of inland extent. Clouds may leak into the southern and western Inland Empire again, with a 30% chance of seeing CIGs at KONT between 12-16z Monday. Gradual clearing/scattering from east to west Monday morning, eventually scattering at the coastal TAF sites 17-18z Monday. .Mountains/Deserts...VFR conditions and unrestricted VIS through Monday afternoon. && .MARINE... No hazardous marine conditions expected through Thursday. && .BEACHES... A modest long period south-southwesterly swell (2-3 feet at 15-17 seconds) will bring some increased surf on Wednesday and Thursday. Breaking waves generally 3-5 feet expected with sets to 6 feet possible, primarily on southerly facing beaches. && .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...Stewey AVIATION/MARINE/BEACHES...Munyan