Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
968 FXUS66 KSGX 201138 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 438 AM PDT Thu Jun 20 2024 .SYNOPSIS... The warming trend will continue through Saturday with high temperatures on Saturday as much as 5 to 10 degrees above average. A shallow intrusion of lower level moisture for the lower deserts will bring warmer nights with days not quite as hot for the weekend. There is also a slight chance of showers and thunderstorms, mainly for the mountains and deserts, for Saturday afternoon and again on Sunday. Then a little drier and continued hot inland for Monday through Wednesday. The marine layer will continue to keep areas near the coast cooler. Night and morning coastal low clouds will continue to spread into portions of the valleys late each night, but may be a little patchier over the weekend. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... .SHORT TERM (Today through Saturday)... The trough of low pressure near the California coast will weaken as high pressure across the south central states expands across the southwest states. The warming trend will continue into the weekend. Saturday is expected to be the hottest day of the weekend for most areas with a Heat Advisory for the valleys, inland Orange County, and the mountains below 5000 feet for Saturday, and continuing for Sunday for the Inland Empire and inland Orange County. A shallow intrusion of lower level moisture into the lower deserts on Saturday morning could limit any additional warming on Saturday with high temperatures a degree to two lower than on Friday. There could be some clouds over the mountains on Saturday afternoon with a slight chance of showers and thunderstorms. The marine layer will remain around 2000 to 2500 feet deep with night and morning low clouds spreading into portions of the valleys late each night. The coverage may be a little patchier for Friday night into Saturday morning. && .LONG TERM (Sunday through Wednesday)... NBM continues to show a slightly greater, though shallow, intrusion of lower level moisture on Sunday morning with a slight chance of showers and thunderstorms on Sunday for the mountains, deserts, and inland valleys. Nights will be warmer for the lower deserts for the weekend into early next week with the modest increase in moisture and high temperatures will warm a few degrees for the middle of next week as the weekend moisture slowly decreases for the early and middle part of next week. There is an Excessive Heat Watch for the San Diego County deserts beginning Saturday and continuing into next week and for the Coachella Valley for Tuesday and Wednesday of next week. With elevations in the San Diego County deserts a few hundred feet higher than the valley floor in the Coachella Valley, there should be less moderating impact on high temperatures for the San Diego County deserts over the weekend from shallow influxes of lower level moisture. && .AVIATION... 200845Z...Coast/Valleys...Areas of low clouds with bases 1300-1500 ft MSL and tops to 2000 ft MSL will continue to spread around 20-25 miles this morning. There is a 50% chance that KONT between 12Z-15Z. Local VIS 3-5 SM in BR/FG where clouds near terrain in the valleys, including VCNTY KRNM. Valleys clearing 14Z-16Z, with coastal areas clearing 16Z-19Z. Areas of low clouds will develop again this evening with bases around 700-1000 ft MSL and tops to 1500 ft MSL, spreading 10-15 mi inland tonight into Fri morning. Mountains/Deserts...Mostly clear with unrestricted VIS will continue through Thu evening. West winds with gusts 20-30 kt through San Gorgonio Pass and on the desert slopes this afternoon and evening. && .MARINE... No hazardous marine weather conditions are expected through Monday. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...Heat Advisory from 10 AM Saturday to 8 PM PDT Sunday for Orange County Inland Areas-San Bernardino and Riverside County Valleys-The Inland Empire. Heat Advisory from 10 AM to 8 PM PDT Saturday for Riverside County Mountains-San Bernardino County Mountains-San Diego County Mountains-San Diego County Valleys. Excessive Heat Watch from Tuesday morning through Wednesday evening for Coachella Valley. Excessive Heat Watch from Saturday morning through Thursday evening for San Diego County Deserts. PZ...None. && $$ PUBLIC...17 AVIATION/MARINE...SS