Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
652 FXUS66 KSGX 190523 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 923 PM PST Tue Nov 18 2025 .SYNOPSIS... Widely scattered, mostly light showers will continue tonight with the potential for additional light wrap around showers into Wednesday afternoon. Another round of scattered light showers develop on Thursday ahead of the next Pacific low pressure system, which will bring another round of more widespread showers Thursday night and Friday with decreasing chances for showers into the weekend. Drier and warmer for next week. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Evening update... Widely scattered light showers continue this evening, mainly across San Diego County. Rainfall rates with these showers will be less than 0.10"/hr. The center of the upper level low is currently over the CA bight and is forecast to move inland across So Cal through Wednesday afternoon. With residual moisture still in place and cold air aloft, additional light showers could develop over the mountains again Wednesday afternoon (15-30% chance). Depending on how the low tracks, wrap around showers could move in from the north during the day Wednesday as well, though confidence in where this showers will track is low. There is around a 10-20% chance of additional rain accumulations of 0.10" or more through 10 PM Wednesday, as high as a 30-40% chance in the mountains, and a 15-20% chance of 0.25" or more in the mountains. Snow levels remain near 5000-5500 ft tonight, increasing to near 6000 ft Wednesday afternoon as the low moves east. Additional snowfall below 7000 ft will generally be less than 1", locally around 1-2" above 7000 ft should wrap around showers materialize in those areas. Otherwise cool on Wednesday with high temperatures around 5-10 degrees normal near the coast and 10-15 degrees below normal elsewhere. Previous discussion... Thursday through Saturday... Attention then quickly turns to the next weather system in the form of yet another closed low that is currently progged to drop southward from northern California on Thursday into Friday. As with most closed lows digging south, volatility in their forecast track/timing and uncertainty is quite high, though ensemble guidance is coalescing towards a scenario where the center of this low drops considerably far south, over northern Baja by Saturday morning. The effect of a low tracking as such brings a cold front through the region some time early on Friday. High resolution guidance now in range suggests the chance for light pre-frontal showers on Thursday, primarily for the coastal areas. The main band of precipitation will accompany the cold front overnight Thursday into Friday though several ensemble members are depicting the potential for wrap around precipitation on the northern side of the low. Given the inherent uncertainty in the track of the closed low, a fairly wide spread in the forecast total rainfall remains for this event. The most likely outcome is to see 0.75-1 inch on the coasts/valleys, with 1-1.5 inches in the mountains, however, should the intensity of the wrap around banding come to fruition as seen a higher-end clustering of ensemble members, localized rainfall totals off the mountains could be closer to 1.5-2 inches. Given the displacement of the center of the low to the south, snow levels will be a touch higher than seen tonight/tomorrow, closer to 6500-7000ft. In addition to the precipitation, wind will also be a notable impact from this second system. Initially, elevated southerly winds ahead of the cold front could bring wind gusts of 20-25 mph to the coasts and coastal waters Friday morning. Then, depending on the track of the upper level low, easterly winds on the north side of the parent storm system could bring easterly winds to the region Friday afternoon, brining strong wind gusts to mountains, mountain passes, the high deserts, and portions of the Inland Empire. Early next week... The late week storm system eventually slides eastward into Arizona/New Mexico on Sunday, though uncertainty in the upper level pattern increases dramatically come early next week. Zonal flow to a weak ridging looks to be the dominant solution, though the timing/intensity of the ridge is in question. Ultimately, temperatures will gradually warm back to near normal for Sunday/Monday. Conditions look to stay dry as well, bringing an end to the wet pattern we`ve been in as of late. && .AVIATION... 190430Z...Areas of SCT-BKN clouds generally 4-8 kft MSL and isolated SHRA, mainly around eastern SD county. Slight (20-30%) for additional ISO SHRA to develop overnight through 15z, with highest chances over the waters and SD County. Remaining clouds gradually scatter out for most places early Wednesday morning. After 18z Wed, cumulus clouds develop over mountains and deserts, with a 25-35% chance for patchy SHRA over these areas Wednesday afternoon. Additionally, FEW-SCT clouds based 2-7 kft MSL develop over the region after 00z Thurs. VFR conditions prevail through the period, with exception of areas with elevated terrain intersecting clouds and locally near SHRA, where VIS reductions and MVFR cigs are possible. && .MARINE... No hazardous marine conditions are expected through Thursday, but the next storm system has the potential to bring hazardous winds and seas Thursday night and 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...SS/DM AVIATION/MARINE...Westerink