Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
611 FXUS66 KSGX 142057 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 157 PM PDT Sun Jul 14 2024 .SYNOPSIS... Monsoon moisture remains in place across southern California while it remains seasonably hot in the deserts. Thunderstorms will occur over the mountains and drift north into the deserts today and then less coverage on Monday. Drying will occur for mid-week with slightly warmer temperatures. Monsoon moisture may return late next week. Night and morning low clouds will continue for the coastal areas into the far western valleys. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Widely scattered thunderstorms have formed in the moisture in place over Socal, confined to the favored terrain where upslope heating and sea breeze winds are merging. A couple cells have been very strong, with hail, heavy rain and frequent lightning. The steering flow is southerly so this is pushing cells off the ridges into the northern Coachella Valley and the High Desert. Activity should quickly fade after 6 pm but moisture remains in place over the region and dewpoints are in the 70s across the Coachella Valley. The surface based thunderstorms will be wet with local heavy rain but a lot of lightning in high CAPE so the very dry fuels from the 2 week heat waves makes for potential starts which may be affected by erratic winds. We will keep the red flag warning in place for consistency given the sensitive fuels and potential strong outflow winds. However, we do have potential for isolated flash flooding in the strongest cells anchored over the mountains today with timing of the sea breeze moving inland with the maximum heating and upslope flow in the terrain. High moisture levels are near 1.5 inches at the border and taper to 1.2 inches over the eastern San Gabriel mountains. Moisture layer is the typical 700 to 500 mb mid level region. Palm Springs ended its 110F or higher streak at 22 consecutive days with a high of 109F yesterday which is expected similar today before getting back to near 115F for mid week. The drying is delayed but appears to occur on Tuesday and this also results in a warm trend for mid week especially inland. High temperatures back to near critical levels in the deserts with areas of major heatrisk developing, maxes near 115F. && .AVIATION... 142015Z...Coast/Valleys... VFR will dominate the area west of the mountains through the rest of the daylight hours. The marine layer with areas of low clouds expected to move inland 02-06Z Mon. Bases are expected to be at 700-1200 ft MSL. Clearing Monday is expected to be along similar timing to this morning with most coastal locations seeing an improvement in ceiling coverage and height 16- 18Z Mon Mountains/Deserts...Peak heating and combined with abundant moisture aloft is allowing for scattered thunderstorms across the mountains and adjacent deserts of San Diego, Riverside, and San Bernardino Counties. Convective activity will likely remain over and east of the mountains, and is expected to decrease around sunset. Strong UDDFS and local sfc gusts to 40 kt expected where storms develop. Local smoke will occur in the San Gabriel Mountains. Otherwise, unrestricted VIS and generally SCT clouds at/above 12000 ft MSL will prevail through early Mon. && .MARINE... No hazardous marine conditions are expected through Friday. && .BEACHES... A Beach Hazard Statement has been issued. For Tuesday Through Thursday. A SSW swell of 3 ft/18-19 sec/210 deg will impact mainly Orange County and Northern San Diego County beaches Tuesday through Thursday. The period will gradually decrease to 15 sec by Thursday. This will bring elevated surf (sets to 6-7 feet) and high risk of dangerous rip currents to south-facing beaches. && .FIRE WEATHER... Surface based thunderstorms this afternoon continuing along the spine of mountains from San Diego county and Mexico border north into the San Gabriel and San Bernardino mountains as well as high deserts. These storms will be wet with local heavy rain but a lot of cloud to ground lightning so the very dry fuels from the 2 week heat waves makes for potential starts which may be affected by erratic winds. We will keep the red flag warning in place for consistency given the sensitive fuels and potential strong outflow winds. Storms further north will have less rainfall as the main moisture source is closer to the Mexico border and tapers to the north and potential for desert foothills lightning. Limited activity tonight but moisture lingers on Monday for similar isolated convection along the higher terrain, moving south to north. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions && .MARINE... No hazardous marine conditions are expected through Friday. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...Beach Hazards Statement from Tuesday morning through Thursday evening for Orange County Coastal Areas-San Diego County Coastal Areas. Red Flag Warning until 9 PM PDT this evening for Riverside County Mountains-Including The San Jacinto Ranger District Of The San Bernardino National Forest-San Bernardino County Mountains-Including The Mountain Top And Front Country Ranger Districts Of The San Bernardino National Forest-San Gorgonio Pass Near Banning-Victor Valley -Apple Valley - Lucerne Valley -Johnson Valley. Excessive Heat Warning until 9 PM PDT this evening for Coachella Valley-San Diego County Deserts. PZ...None. && $$ PUBLIC...Tardy AVIATION/MARINE...Suk