Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
076 FXUS66 KSGX 242137 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 137 PM PST Sun Nov 24 2024 .SYNOPSIS... Dry conditions for the rest of today. Temperatures will fluctuate between slightly below normal and slightly above this week. Additional chances of precipitation Monday for the High Desert and San Bernardino mountains. Rain chances expand for Tuesday and Wednesday, with at least slight chances for places in and west of the mountains. Periods of gusty westerly winds for the mountains and deserts are expected Tuesday into Wednesday. Dry conditions are expected for the Thanksgiving holiday. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... The upper level pattern is expected to stay mostly zonal over Southern California for Monday but a low pressure system digging south along the Pacific Northwest will allow for heights to fall and for moisture to reach the northern portions of our forecast area. Latest guidance is indicating some light accumulating precipitation is possible in the High Desert and San Bernardino county mountains Monday. Based on current guidance it looks unlikely for precipitation to make it to Orange County or the Inland Empire Monday. A tenth of an inch or less of rain is expected for the High Desert and western portions of the San Bernardino county mountains on Monday. As the low pressure system moves east into the upper Great Basin on Tuesday, weak troughing is expected over Southern California which will allow the moisture to move south, reaching San Diego county by Tuesday evening. Up to a tenth of an inch of rain is expected to accumulate in Orange County, the Inland Empire, and the San Bernardino county mountains for Tuesday through Wednesday morning. There is a 10 to 20 percent chance some locations in northern Orange County and Inland Empire could exceed 0.25", with a 35 percent chance of exceeding 0.25" of rain in the San Bernardino mountains. Mostly light rain is expected for San Diego county, with only a 5 to 10 percent chance of rainfall totals exceeding 0.10", highest chances in northern San Diego county for Tuesday through Wednesday morning. In addition to periods of rain, westerly winds will increase for Tuesday night into Wednesday. Winds will be strongest over the mountains into the deserts. Peak gusts will be 35 to 45 mph, local gusts up to 50 mph are possible in wind prone passes and canyons. Snow levels for Monday through Wednesday are expected to stay above 8000 ft. Dry conditions are expected for Wednesday night into Thursday with weak ridging over Southern California. Temperatures will be near to slightly below normal through Wednesday, becoming near to slightly above normal for the end of the week away from the low deserts. In the low deserts temperatures will remain near to slightly above normal for the forecast period. There remains some uncertainty in the forecast for next weekend. Global models are depicting a ridge of high pressure over the Pacific Northwest with a trough of low pressure off the coast of Southern California. Historically, this is a tricky set up for models to depict correctly and global model ensemble solutions continue to show differences in placement and amplitude of the previously mentioned ridge and trough. Most model solutions are leaning drier for Friday, although some individual members of the GEFS and ECMWF still show the potential for precipitation, especially for areas north of San Diego County. About 50 percent of ensemble solutions are trending wetter for Saturday. Current forecast for Friday and Saturday follows the NBM with slightly higher chances of precipitation on Saturday vs Friday. Hopefully, subsequent runs will bring more clarity on if the forecast will trend drier and warmer or wetter and cooler for next weekend. && .AVIATION... 242030Z...Coast/Valleys...FEW low clouds with bases below 3000ft MSL possible tonight and into early Monday morning, but CIGs are not expected. SCT-BKN clouds above 10,000ft MSL will prevail through tomorrow with mostly unrestricted VIS. Mountains/Deserts...SCT-BKN clouds with bases to 10,000+ft MSL will continue through Monday morning with mostly unrestricted VIS. Local west surface gusts 20-30kts will occur over mountain crests/desert slopes through Monday morning. && .MARINE... No hazardous marine weather is expected through Thursday. && .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...CO AVIATION/MARINE...Zuber