Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
180 FXUS66 KSGX 252013 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 113 PM PDT Tue Jun 25 2024 .SYNOPSIS... High pressure over the Desert Southwest will help bring in southerly moisture again today, providing another chance for isolated showers and thunderstorms across northern mountains and deserts. As the ridge amplifies over the Southwest, moisture will push to the east, bringing in drier but continued warm weather through Thursday. A trough to the north will try to influence our weather by the end of the week, leading to a slightly deeper marine layer and temperatures a few degrees cooler by Friday and Saturday. High pressure will make a return by early next week, prompting slightly warmer conditions. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Taking a look out our office window and at GOES imagery, one can see cumulus clouds locally building over the mountains this afternoon, most of them over the eastern San Bernardino Mountains. Clockwise flow around an area of high pressure of the Desert Southwest places us right on the edge of the moisture plume today. These clouds may generate light showers or a weak thunderstorm for areas near Big Bear into portions of the High Desert, mainly east of Interstate 15. The ridge will amplify across West Texas and New Mexico, swaying the moisture axis eastward. This will lead to minimal chances for storm activity. Warm conditions will prevail through much of the week. The ridge to the east weakens slightly by Friday, allowing lower heights and more zonal flow to come into the region. This will knock temperatures down a few degrees across the area by Friday, leading to near average daytime highs. Heat risk will lower as well, mainly due to overnight temperatures not being as warm with lows near to a few degrees below normal. Winds will be breezy across the typical spots in passes into the deserts; most models indicating winds 20-35 MPH most afternoons and evenings, highest in the San Gorgonio Pass with gusts near 35-45 MPH. The marine layer will also become slightly deeper by this time, with greater coverage of low clouds and fog for areas west of the mountains. An area of high pressure will grow and expand across the Pacific by early next week, which will lead to another subtle warm up with temperatures slightly above average away from the coast. This will decrease the marine layer depth, leaving low clouds and fog to occur closer to the coast. && .AVIATION... 252000Z...Coast/Valleys...Mostly clear skies with the exception of a few high clouds will prevail through this evening. There`s a greater chance tonight compared to last night for lower clouds, with a 50-60 percent chance of CIGS at the coastal airports after 08Z-10Z Wed with bases around 800-1200 ft MSL, locally down to 700 feet. Otherwise, FEW-SCT clouds at/above 15,000 ft MSL and unrestricted VIS through Wed morning. Any clouds that do develop at coastal TAF sites will likely clear 16-18Z Wed. Typical afternoon breeziness expected each afternoon. Mountains/Deserts...There is a 15-20 percent chance of TSRA over the San Bernardino Mountains north into the high desert this afternoon into the early evening, with CB bases near 12,000 ft MSL and tops to 25,000 ft MSL. Gusty outflow winds and reduced VIS VCTY TSRA. Otherwise, FEW-SCT clouds at/above 15,000 ft MSL and unrestricted VIS through Wed morning. Typical afternoon breeziness expected each afternoon. && .MARINE... No hazardous marine conditions are expected through Sunday. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...Excessive Heat Warning until 8 PM PDT Thursday for Apple and Lucerne Valleys-Coachella Valley-San Diego County Deserts- San Gorgonio Pass Near Banning. PZ...None. && $$ PUBLIC...APR AVIATION/MARINE...CSP