Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
584 FXUS66 KSGX 141634 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 934 AM 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... The past 24 hours had about 2000 total lightning flashes from ocean to mountains and across the deserts. This includes lightning early this morning across the San Gabriel mountains west of Wrightwood and lots of strikes over the ocean yesterday as well as the Mojave desert. The steering flow is veering to south and slightly less today, so we expect surface based thunderstorms to form along the spine of mountains 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 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. 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 1.4 inches at the border and taper to 1.1 inches over the eastern San Gabriel mountains. Moisutre 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. && .AVIATION... 141600Z...Coast/Valleys...Marine Layer stratus Deck and fog is beginning to lift and mix out this morning. Bases are expected to be 700-1200 ft MSL with tops to 1500 ft MSL. Most areas will clear by 17Z Sun. 15-20% chance local BKN/OVC conditions will linger near beaches through Sun afternoon. Otherwise, unrestricted VIS and generally SCT clouds at/above 10000 ft MSL will prevail, with areas of low clouds expected to move inland 02-06Z Mon. Bases are expected to be similar at 700-1200 ft MSL. Mountains/Deserts...There is a slight chance of TSRA 20Z Sun-03Z Mon with CB bases around 10000 ft MSL and tops to 40000 ft MSL. Highest chances of TSRA will be in the mtns (20-30%) with lesser chances in the deserts (15-20%). 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 SSW swell of 3 ft/18-19 sec/210 deg will impact mainly Orange 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 today should form 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. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...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/FIRE WEATHER...Tardy AVIATION/MARINE...Suk