Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
388 FXUS66 KSGX 070356 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 856 PM PDT Sat Jul 6 2024 .SYNOPSIS... Above normal high temperatures will continue through next week as persistent ridging blankets the western United States. Highs fall a degree or two on Sunday and Monday before warming again on Tuesday. Monsoonal moisture may reach the lower deserts and mountains late week as the ridge axis shifts eastward. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Evening update... Quite the change from yesterday as a stronger gulf surge brough upper 50s to mid 60s dew points into the lower deserts today, limiting the heating. In fact, the high at Palm Springs was "only" 114 today, down 10 degrees from yesterday! West of the mountains, a coastal eddy helped spread cooling further inland resulting high temperatures around 7 to 10 degrees lower than yesterday. High res guidance suggests similar conditions tomorrow with little change in marine layer depth and another gulf surge into the lower deserts, as well as minor cooling at 850 mb. Moisture becomes less of an influence on Monday with mid-level warming, so expect a sharp increase in temps, especially across the lower deserts. Adjusted max temperatures across the forecast period to account for these daily influences that haven`t been captured well by NBM. Only other change this evening was allowing heat products to expire for Inland Orange County, the Santa Ana Mountains, and the San Diego County Valleys. All other heat products remain in effect and are unchanged. Previous discussion... Ensemble guidance shows increasing positive height anomalies by the middle of the week, leading to a noticeable uptick in highs by Tuesday. Highs for Tuesday through Thursday will remain pretty steady, with highs topping out 5-8 degrees above normal at the coast, and 5-15 degrees above normal in the valleys, mountains and deserts. Forecast Highs Tuesday-Thursday: Coast: upper-70s to low-80s. Inland Orange/San Diego County Valleys: mid-80s to mid-90s, approaching 100 degrees along the foothills in San Diego County. Inland Empire: upper-90s to 108. Mountains: upper-80s to low 100s. High Desert: 105-111. Lower Deserts: 113-122. The ridge axis progresses eastward through this week, settling near the Four Corners region by late week. The placement of the ridge could lead to a turning of mid-level winds, increasing mid- level moisture, and a slight (10-15%) chances of thunderstorms mainly in the mountains. This monsoon signal begins with minor chances by Thursday, increasing some by Friday and Saturday per global ensemble guidance. && .AVIATION... 060300Z...Coast/Valleys...Low clouds bases 800-1100 ft MSL redeveloping along beaches this evening, moving inland to 15-20 miles overnight. Bases expected to lower in areas overnight to 400-800 ft MSL with an accompanying reduction in VIS to 3-5 SM in BR, locally down to 1-3 SM for inland areas. There is a 30-40% chance of CIGs occurring at KONT and surrounding areas overnight, with best chances 12-15z Sun. Clouds scatter out to the coast Sun 15-18Z, but with areas of lingering cloudiness along beaches into the afternoon. More low clouds with similar bases moving back onshore after 02-03Z Mon. Mountains/Deserts...Mostly clear skies with unrestricted vis through Sunday. && .MARINE... No hazardous marine conditions are expected through Thursday. && .BEACHES... A long-period south swell will continue to create elevated surf but gradually subside through Sunday. Sets up to 6 feet can be expected on south and southwest-facing beaches, especially in Orange County. Check the Beach Hazards Statement for details. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...Beach Hazards Statement through Sunday afternoon for Orange County Coastal Areas-San Diego County Coastal Areas. Excessive Heat Warning until 9 PM PDT Sunday for Riverside County Mountains-San Bernardino County Mountains-San Bernardino and Riverside County Valleys-The Inland Empire- San Diego County Mountains. Excessive Heat Warning until 9 PM PDT Wednesday for Apple and Lucerne Valleys-Coachella Valley-San Diego County Deserts- San Gorgonio Pass Near Banning. PZ...None. && $$ PUBLIC...SS AVIATION/MARINE/BEACHES...CSP