Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
494 FXUS66 KSGX 262131 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 131 PM PST Tue Nov 26 2024 .SYNOPSIS... An influx of moisture associated with an atmospheric river in Central California will shift southward tonight, bringing very light showers to much of the region, with totals generally under 0.05". By Wednesday afternoon, weak upper ridging builds in with drier and warmer conditions prevailing through the weekend. A closed upper level low moves into California early next week, although associated moisture and rain chances look minimal at this point. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Ample moisture and energy continues to flow into Central California as a weakening atmospheric river (AR) is pushed southward by an upper level trough moving into the Great Basin. Precipitation chances spread down into Southern California this afternoon and evening, although rainfall totals look mediocre at best given the weakening AR. Currently, totals through Wednesday morning will be less than 0.10" for most coastal and inland areas, with the mountains and coastal slopes seeing totals closer to 0.15-0.40" while areas east of the mountains remain dry. Snow levels will be fairly high for this event, generally above 8300-9400ft through Wednesday. Confidence is decreasing regarding noticeable precipitation making it down to the San Diego County coast and valleys, but should the rain make it this far south, timing will be early Wednesday morning. Outside of the rain, winds will be increasing in the mountains this afternoon, peaking this evening and overnight with gusts up to 45 mph near the ridges, desert slopes, and mountain passes. Gusts up to 35-40 mph will spread to the deserts and Coachella Valley this afternoon, and given the lack of rainfall expected on the eastern sides of the mountains, periods of blowing dust and visibility reductions will be possible. Winds weaken and any lingering rain across the region will move out by late Wednesday morning. With the departure of the AR, zonal flow settles in for the second half of the week, with drier weather and temperatures slowly warming to near normal or slightly above. By Saturday, weak upper ridging builds in and temperatures reach 5-10 degrees above normal for the end of November. Models continue to show an upper low off the West Coast attempt to move inland this weekend, but recent trends have strengthened the ridge, with the low and associated precipitation falling apart prior to making it to California. At this time, the warmer weather looks to hold with dry conditions continuing into next week. Tuesday and beyond, there remains stark differences in the models regarding the upper level pattern, with some showing another low forming off the coast while others maintain the hot and dry weather. Stay tuned. && .AVIATION... 262100Z....Coast/Valleys/Mountains...SCT-BKN clouds across the Inland Empire and Orange County through 00Z. Cigs will lower to 1500- 2500 ft MSL 00Z-04Z Wednesday and spread south into San Diego County. SCT -SHRA will move from northwest to southeast generally 23- 12Z, with additional isolated light showers diminishing by 18Z Wed. CIGS/vis may briefly drop to around 800 ft/4 SM in SHRA. Coastal mountain slopes will be obscured in clouds/fog through Wednesday morning. SCT conditions expected 18-22Z Wed starting in the Inland Empire and clearing to the south and west. 40 to 50 percent chance of cigs 1500-2000 ft MSL lingering in San Diego county Thursday afternoon. Winds will become northeast on the San Bernardino mountain foothills starting 14Z Wednesday. Northeasterly winds will reach the Inland Empire around 18Z. Gusts up to 35 kt possible on the San Bernardino mtn foothills into the Inland Empire. Desert Mountain Slopes/Deserts...SCT-BKN high clouds with bases AOA 10000 ft MSL and unrestricted vis through Wednesday morning. Breezy southwest winds along the desert slopes and into the deserts will continue through 15Z Wed. Peak gusts of gusts to 25-45 kt expected. MOD up/downdrafts and areas of LLWS possible over and NE/E of the mountains. && .MARINE... No hazardous marine weather is expected through Sunday. && .BEACHES... A 2-3 ft south swell from 190 deg at 17-20 sec will produce elevated surf of 3-5 with with sets to 6 feet on south facing beaches Wednesday and Thursday. Strong rip currents can be expected. Swell and surf will begin to slowly lower on 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...Zuber AVIATION/MARINE...CO