Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
401 FXUS66 KSGX 242028 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 128 PM PDT Mon Jun 24 2024 .SYNOPSIS... Hot conditions will continue in the deserts through Thursday, with a gradual cooling west of the mountains into the the middle of the week. There is a slight chance of showers and thunderstorms for the mountains into the High Desert this afternoon and early evening with decreasing chances for Tuesday afternoon. Dry conditions expected for the middle of the week into the weekend, with marine layer low clouds and fog returning to the coast and portions of the valleys. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Visible satellite imagery at 1:30 PM was showing cumulus developing along the mountains, but so far no precipitation or lightning has been detected. Similar to yesterday, the convection will likely start late in the afternoon. The places most likely to see shower or thunderstorm activity will be along the convergence boundaries in the mountains and High Desert. Chances of isolated showers and thunderstorms are in the forecast for Tuesday afternoon in similar locations, but chances are lower due to gradually decreasing moisture. Temperatures in the valleys and mountains this afternoon are running 3 to 7 degrees cooler than 1:30 PM yesterday afternoon. The immediate coast and deserts are running a few degrees warmer than 1:30 PM yesterday afternoon. Areas west of the mountains are expected to see additional cooling into Tuesday and Wednesday. Highs in the deserts will fluctuate a few degrees each day through Thursday before a couple degrees of cooling is expected for Friday. One of the main drivers of the elevated heat risk this weekend was the above average low temperatures. Low temperatures will gradually decrease through much of this week. This will help decrease the heat risk in the deserts Friday and Saturday even though high temperatures will only decrease a degree or two. Additional warming is expected by next weekend with the greatest warming for the coast and valleys on Saturday and for the deserts on Sunday. There is still some uncertainty surrounding the forecast for next weekend into early next week, largely centered around how ridges building in the Southeast and over the East Pacific will interact with the trough moving through the Pacific Northwest this weekend. The temperature spread is most noticeable for the valleys with narrower spread for the deserts. && .AVIATION... 241955Z...Coast/Valleys...FEW-SCT clouds at/above 10,000 ft MSL and unrestricted vis through this evening. There is a 15-25 percent chance of low clouds with bases 1000 ft MSL or less developing along the San Diego County coast after 09Z Tue. Mountains/Deserts...There is a 10-15 percent chance of TSRA over the San Bernardino Mountains and portions of the high desert this afternoon, with CB bases near 10,000 ft MSL and tops to 25,000 ft MSL. Gusty outflow winds and reduced vis in RA VCTY TSRA. Otherwise FEW-SCT clouds at/above 10,000 ft MSL and unrestricted vis through Tue night. && .MARINE... No hazardous marine conditions are expected through Friday. && .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...CO AVIATION/MARINE...Small