Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
265 FXUS66 KSGX 070420 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 920 PM PDT Mon May 6 2024 .SYNOPSIS... Dry with temperatures similar to a few degrees warmer than Monday are expected Tuesday. Periods of gusty westerly winds in the mountains and deserts expected Tuesday with a brief period of offshore winds Wednesday morning. Marine layer low clouds and fog are possible within a few miles of the coast most nights and mornings for the next few days. Another gradual warming trend looks likely heading into this weekend. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Satellite imagery at 9 PM was showing mostly clear skies across the area. High resolution model guidance is indicating a coastal eddy will develop overnight into Tuesday morning. If the eddy develops as forecast, patchy low clouds could develop near the coast closer to sunrise Tuesday morning. High temperatures on Tuesday are expected to warm a few degrees compared to Monday west of the mountains, with temperatures 5 to 7 degrees warmer on Tuesday in the deserts. A passing shortwave Tuesday evening will keep the onshore pressure gradient enhanced and bring another round of breezy westerly winds to the mountains and deserts. Peak gusts of 40-50 mph are expected during the late afternoon and evening hours. Strongest winds will be below mountain passes and through wind-prone canyons. From the Previous Discussion... The development of a very strong upper level low pressure system over the Northern High Plains, and its influence expanding westward as it strengthens, will cause a quick bout of offshore flow on Wednesday. It will drop temperatures in the deserts by a few degrees but will continue the warming trend for areas west of the mountains. The offshore flow itself does not appear to be overly impactful, with perhaps a few gusts of 30-35 mph in the Santa-Ana-favored areas below passes and through canyons. The forecast then gets a bit more murky from Thursday onward. The aforementioned strong upper low will cause a larger-scale troughing pattern to set in over SoCal. This will support a deeper marine layer with clouds and fog extending farther inland. Temperature trends during this time look to be highly dependent on marine layer coverage and duration of low clouds each morning/afternoon. Eventually the low and attendant trough look to weaken which would support another gradual warming trend, though exactly when that will take place appears uncertain at this time. && .AVIATION... 070400Z...Coasts/Valleys...Patchy BKN/OVC low clouds will develop within 15 miles of the coast 10Z-13Z Tue and continue through 15Z- 17Z Tue with bases 1200-1500 ft MSL and tops to 1700 ft MSL. There is around a 60 percent chance KSAN and KCRQ will have a CIG but only a 40 percent chance of a CIG at KSNA. Local VIS 3-5 miles will occur in BR in the valleys 11Z-16Z Tue. Otherwise, mostly clear skies with unrestricted VIS will prevail through most of Tue evening, though stratus will likely develop along the coast late Tue evening. Mountains/Deserts...Mostly clear skies with unrestricted VIS will continue through Tue evening. && .MARINE... Wind gusts near or slightly over 20 knots will occur Tuesday late afternoon and evening near San Clemente Island. Otherwise, no hazardous marine conditions are expected through Saturday. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...None. && $$ PUBLIC...CO/Adams AVIATION/MARINE...Maxwell