Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
050 FXUS66 KSGX 201534 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 834 AM PDT Thu Jun 20 2024 .SYNOPSIS... A 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 less extensive coverage. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Marine layer is shallower this morning with a top around 2200 feet MSL so it extends only into parts of Riverside but most of the Inland Empire is sunny. In San Diego county it follows along but just east of I-15 for inland extension. We should see good burn off in normal fashion this morning. The upper level heights rise on Friday so the marine layer will squash further but persist and become less organized in coverage and only weak eddy formation. The heat wave still on track with warming Friday and Saturday for all areas. The moisture surge starts Saturday and continues into Sunday. The instability is very marginal and mostly in the Colorado River valley for Saturday but enters into San Diego mountains as well. This expands on Sunday with moderate instability due to the moisture increase across our mountains. The 850 mb temperatures peak at 32C in the lower deserts under 594 DM 500 mb heights so this looks to be the warmest of season and also prolonged before the upper ridge weakens slightly late next week. .AVIATION... 201525Z...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. 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. && .FIRE WEATHER... Fuels have dried to normal levels over inland areas where temperatures have been running above normal past 2 months. && .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 1&&0 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/FIRE WEATHER...Tardy AVIATION/MARINE...Small