Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
224 FXUS66 KSGX 241632 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 932 AM PDT Mon Jun 24 2024 .SYNOPSIS... Hot conditions will continue in the deserts 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 for this afternoon and early evening with lesser 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... Temperatures at 9 AM today were running 3 to 7 degrees cooler than yesterday for the valleys, mountains, and High Desert. Temperatures along the immediate coast and in the low deserts at 9 AM were a mix of about the same as yesterday to a degree or two warmer. High temperatures today are expected to be 2 to 5 degrees cooler than yesterday west of the mountains with no significant change in the deserts. The cooling trend will continue for areas west of the mountains for much of this week. Highs in the deserts will fluctuate a few degrees each day through Thursday before a few degrees of cooling is expected. One of the main drivers of the elevated heat risk this weekend was the above average low temperatures. Low temperatures will gradually decrease through this week. This will help decrease the heat risk, especially 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 uncertainty in the temperature forecast is most noticeable for the valleys with narrower spread for the deserts. Slight chances of isolated showers and thunderstorms are in the forecast this afternoon, with lesser chances on Tuesday afternoon. The 12Z sounding from KNKX was still showing 1.69 inches of precipitable water and just over 600 J/kg of CAPE. The limiting factor this afternoon will again be a large-scale lifting mechanism. The places most likely to see shower or thunderstorm activity will be along the convergence boundaries in the mountains and High Desert. && .AVIATION... 241555Z...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