Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
276 FXUS66 KSGX 090959 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 259 AM PDT Thu Oct 9 2025 .SYNOPSIS... A low pressure system off the West Coast will draw moisture from Tropical Storm Priscilla northward into the area for today through Saturday morning, with chances for showers and a chance for thunderstorms at times. Cooler with drying and a return of the marine layer for Saturday through Monday. For Tuesday and Wednesday of next week, a low pressure system moving southward along the West Coast will bring a chance of showers along with stronger westerly winds. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Patches of low clouds persist in the San Diego County coastal areas and valleys this morning but are not showing signs of increasing in coverage while mid and high clouds are moving in from the south on the edge of a plume of deep-layer moisture from Tropical Storm Priscilla. The bulk of the moisture from Priscilla will stay to the south and east of San Diego County but enough moisture should make it into the region for a chance of showers and potentially isolated tstms from the deserts to the coast and from San Diego County north to southwestern San Bernardino County, beginning later this morning. Showers will be mostly light but heavier showers could develop this afternoon into this evening. Scattered light showers could continue tonight into Friday morning. More widespread and heavier showers/tstms are likely Fri afternoon/evening, and light showers could persist into Saturday morning. Due to the showery nature, rainfall amounts will vary greatly but will range from a few hundredths in the coastal areas and valleys to nearly an inch in some mountain locations between today and Saturday. Heavier showers or tstms could produce locally heavy rainfall, as much as 0.60 inch per hour. By Friday night, Priscilla will become absorbed into the southwesterly flow between the low pressure system to our northwest and the high pressure centered near the TX/MX border. As this process continues, available moisture will be transported to the northeast. Sunday and Monday will see a return to dry and more typical conditions as the low pressure system moves inland and the upper closed low becomes an open wave over the Rockies...leaving an area of broad troughing over the western US. Temperatures will remain below seasonal averages and the marine layer low clouds will return for Sat and Sun nights. For next Tue and Wed, another low pressure system moving south over the west coast will bring cooler and windy conditions along with more chances for precipitation. At this time, the spread among model solutions makes the forecast more uncertain but a plurality of ensemble solutions across model platforms indicate precipitation moving in from the northwest as early as Tuesday morning and lasting through Wed morning. && .AVIATION... 090930Z....Patchy coastal/valley low clouds with bases around 1500- 2000 feet MSL will continue through 14Z mainly in San Diego County. Otherwise, clouds at or above 12000 feet will thicken and lower during the morning to 6000-9000 feet, and bring isold -SHRA and sprinkles through tonight. Isold TSRA after 18Z, most likely inland. Any TSRA could lower cloud bases to 4000 feet MSL briefly, and could bring gusty winds and reduced vis in +RA. && .MARINE... Northwest winds occasionally exceeding 20 knots around San Clemente Island during the afternoons and evenings Friday and Saturday. There is a slight chance of thunderstorms today through Friday, most likely during the afternoons. Lightning, erratic winds, choppy seas, and/or reduced visibility in heavy rain is probable in the vicinity of any thunderstorm. && .BEACHES... There is a 5-15% chance of thunderstorms producing lightning today and Friday, most likely during the afternoons. && .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...PG AVIATION/MARINE/BEACHES...MM