Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
531 FXUS66 KSGX 161543 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 843 AM PDT Tue Jul 16 2024 .SYNOPSIS... Seasonal weather will continue this week with only small day to day variations. There is a slight chance of thunderstorms most days, mainly in the mountains during the afternoons. Coastal low clouds and fog will continue to reach into western valleys each night and morning. Temperatures will climb well above normal heading into the weekend. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Low clouds and fog made it all the way into Murrieta this morning, something the Murrietans haven`t seen for a while. But the low cloud deck didn`t even cover most of Los Angeles. The morning sounding from San Diego shows a really strong inversion, which will make complete clearing more of a struggle, either late or not at all at the immediate coast. But the holes in the low cloud deck over the water might put holes in this clearing theory. Monsoon moisture has taken a step backward today, and the morning sounding shows a capping inversion at about 19,000 feet. Both factors will lead to fewer showers and thunderstorms today than we had yesterday. Right now it looks like isolated stuff between about noon and 4 pm and only over the mountains. A high pressure ridge over the West will strengthen a little each day Wednesday into Saturday. That will bring a modest warming trend taking near normal high temperatures Wednesday to 5-10 degrees above normal over the weekend. That will mean going above 100 in parts of the Inland Empire and above 115 in parts of the lower desert. One caveat to watch for is how much if any low level moisture seeps into the low desert each morning. This moisture would literally dampen any temperature rise. But it really doesn`t matter: the heat risk will be high whether the temp gets to a dry, scorching 118 or a humid, sweltering 108. With the high over the West strengthening, the marine layer will get suppressed slightly and low clouds would not make it into inland valleys. But the warm air mass and strength of the high will keep the marine inversion nice and strong. No, the low clouds aren`t going anywhere, just backing off a step. The monsoon moisture backs off a little more Wednesday, but a subtle resurgence arrives Thursday to increase the chances of thunderstorms, mainly during the afternoon in the mountains. Copy and paste this idea each day for Friday through Monday. One interesting trend of note: today`s guidance shows less monsoon moisture for the weekend than yesterday`s guidance showed. The strong high pressure over the West is also not going anywhere, so it looks like temps will remain well above normal next week. && .AVIATION... 161500Z...Coast/Valleys...Stratus with bases 1200-1900 ft MSL and tops to 1800-2300 ft MSL has spread inland 15-25 mi, but are starting to gradually retreat west towards beaches this morning. Clouds clearing inland through 17Z and near the coast 17-20Z, likely slowest in south San Diego Co. with locally thicker stratus. Locally BKN conditions at the beaches through the afternoon. Stratus spreading back into the coastal areas after 17/01Z and up to 20-25 mi inland by 17/10Z. Similar bases and tops expected, scattering out 17-19Z Wed. Mountains/Deserts...ISO SHRA/TSRA developing over the mountains and desert slopes by 20Z, dissipating by 17/02Z. CB bases near 12,000 ft MSL with tops to 30,000 ft MSL. Gusty outflow winds and reduced vis in RA VCTY TSRA. Otherwise FEW clouds at/above 10,000 ft MSL and unrestricted vis through Wed morning. && .MARINE... No hazardous marine conditions are expected through Saturday. && .BEACHES... Long period SSW swell (200-210 degrees) of 3ft/16-18sec will bring elevated surf of 4-6 feet with sets up to 7 feet for south and southwest facing beaches in Orange and San Diego counties. There is a high risk of rip currents at all beaches. A Beach Hazard Statement is in effect from 9 AM this morning through Thursday evening. Swell and surf will begin to lower on Thursday. && .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 Thursday evening for Orange County Coastal Areas-San Diego County Coastal Areas. PZ...None. && $$ PUBLIC...MM AVIATION/MARINE/BEACHES...CSP/SMALL