Area Forecast Discussion
Issued by NWS San Diego, CA

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000 FXUS66 KSGX 191620 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 920 AM PDT Fri Apr 19 2024 .SYNOPSIS... Cooler today with coastal low clouds extending inland across most of the valleys this morning and with gusty southwest to west winds for the mountains and deserts for this afternoon into tonight with the stronger gusts to 45 to 55 mph. Warming for Saturday and Sunday with Sunday high temperatures a few degrees above average near the coast to 10 to 15 degrees above average for inland areas. Greater cooling will spread inland for Monday through Thursday with Thursday high temperatures as much as 10 to 15 degrees below average for the mountains and inland valleys. Coastal low clouds will become more extensive next week and may extend onto the lower coastal mountain slopes for the middle of next week. && .DISCUSSION...
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FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... .Morning Update... A weak costal eddy formed overnight in the presenece of a weak trough overhead, leading to extensive low cloud coverage for areas west of the mountains and clearer skies across higher elevations into the deserts. Slow clearing is occurring across portions of the Inland Empire this morning. Most valleys should clear this morning, but confidence is low to moderate in significant clearing toward the coast later this afternoon. A similar low cloud pattern will occur tonight. The windiest day across the mountains and deserts this week will be today, where a Wind Advisory is in effect for areas of the San Gorgonio Pass, including along Interstate 10, so make sure to travel with care this afternoon and tonight. Slightly warmer this weekend with warmer weather and less wind. A closed low will form off the Pacific, leading to cooler and breezier weather next week. .Previous Discussion (439 AM Friday)... .SHORT TERM (Today through Sunday)... A weak low pressure system centered just west of Point Conception will move quickly inland across the area today. The marine layer has deepened to around 3000 feet with low clouds over the coastal waters extending inland across most of the valleys. There are also a few high clouds. There will be stronger onshore flow with gusty southwest to west winds for the mountains and deserts for this afternoon into tonight with the stronger gusts to 45 to 55 mph. The strongest gusts will be in the northern Coachella Valley below the San Gorgonio Pass with gusts to 65 mph. High temperatures today will be a few to around 5 degrees cooler than Thursday for most areas with high temperatures for the coast and valleys mostly a few to around 5 degrees below average with the deserts still around 5 degrees above average. For the weekend, high pressure aloft will bring a warming trend with the marine layer becoming shallower by Saturday night and Sunday. Saturday will be a few degrees warmer than Friday at lower elevations to around 5 degrees warmer for the mountains, then a few degrees warmer on Sunday for the lower deserts to 5 to 10 degrees warmer for the inland valleys. With the warming, high temperatures on Sunday will be a few degrees above average near the coast to 10 to 15 degrees above average for the deserts, mountains, and inland valleys. High temperatures on Sunday for the lower deserts will be mostly in the 90s. NBM has a 64 percent chance on Sunday and again on Monday for Palm Springs to have a high temperature of 100 or higher.
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&& .LONG TERM (Monday through Thursday)... A low pressure system over the eastern Pacific will eventually move inland through southern California and northern Baja some time around the middle of next week. Cooling will begin to spread inland on Monday with the cooling continuing through Thursday. With the cooling, high temperatures on Thursday will be around 10 to 15 degrees below average for the mountains and inland valleys. There do remain model differences on the speed and timing of the inland movement of the low pressure system around the middle of next week. This will affect how quickly and when the marine layer will deepen sufficiently for night and morning coastal low clouds extend well inland and onto the lower coastal slopes of the mountains. && .AVIATION...
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191520Z...Coast/Valleys...Widespread marine low clouds with bases near 2000 feet and tops 2800 feet producing MVFR ceilings of 1000 to 2300 feet above ground level. Since the layer is thin there should be partial burn off in most areas 19 to 22 UTC but a weak disturbance tracks through Socal near 00 UTC/20 which will affect the marine layer. The marine layer will fill back inland from 01 to 04 UTC with similar widespread coverage but becoming slightly lower by 500 feet in the wake and sinking air of the weather disturbance. Otherwise...SCT cumulus at around 12000 feet over mountains between 19-02Z and SCT clouds at/above 20000 feet MSL with unrestricted VIS today and tonight. Surface wind increase to 20 knots sustained from 00 to 03 UTC today for the Coachella Valley.
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&& .MARINE... No hazardous marine conditions are expected through Tuesday. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX WATCHES/WARNINGS/ADVISORIES...
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CA...Wind Advisory until 3 AM PDT Saturday for San Gorgonio Pass Near Banning. PZ...None.
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&& $$ MORNING UPDATE/PREVIOUS PUBLIC...APR/17 AVIATION/MARINE...Tardy

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