Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
082 FXUS66 KSGX 020420 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 920 PM PDT Wed May 1 2024 .SYNOPSIS... A shallower marine layer, with warmer conditions expected for Thursday and Friday. A passing low pressure system will bring increased cloud coverage, cooler conditions, periods of gusty westerly winds, and a slight chance of precipitation to the area Saturday into Sunday. Drier and warmer conditions expected early next week. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... No significant changes to the forecast tonight as a coast eddy is going to be the main driver of weather over near the California Bight for the rest of the week. .Previous Discussion... 121 PM Wed May 1 2024 A coastal eddy is expected remain present over through at least Saturday, which will help maintain areas of night and morning low clouds and fog. Even with the eddy the marine layer is expected to get shallower tonight and Friday night. Low clouds and fog are forecast to reach into the valleys, but are not expected to completely fill in the coastal basin. Conditions are expected to warm a few degrees Thursday with another warm day expected on Friday. On Saturday, an incoming low pressure system is expected to push the weak ridge over us to the east. This will bring a few degrees of cooling for Saturday, with even more cooling on Sunday as the low digs into the Great Basin. Highs on Sunday are expected to be 5 to 10 degrees cooler than Saturday west of the mountains and 10 to 15 degrees cooler than Saturday in the mountains and deserts. Monday and Tuesday are expected to be warmer, but highs will still be below average on Tuesday. The onshore pressure gradient will increase over the weekend enhancing westerly winds over the mountains, through passes, and into the deserts. There is still some uncertainty in the strength of the winds but there is 30-40 percent chance of wind gusts between 40- 60 mph, with a 20 percent chance of gusts exceeding 60 mph. The most likely place for gusts to exceed 60 mph are through passes and canyons, like the San Gorgonio Pass. Winds will peak in strength late Saturday into Sunday afternoon before decreasing Sunday night into Monday. The passing low will dig far enough south to bring chances of precipitation to Southern California Saturday night into Sunday. Rainfall is expected to be mostly light and confined to areas in and west of the mountains. Highest chances of precipitation Saturday night into Sunday are in the mountains at 30-45 percent, chances for the coast and valleys are mostly 15-25 percent. Highest rainfall totals will likely be in the mountains, with a 30-40 percent chance of a quarter of an inch or more accumulating. For the coast and valleys, rainfall totals will most likely be less than 0.20 inch. Dry conditions are expected to return by Monday. && .AVIATION... 020400Z...Coasts/Valleys...Areas of BKN-OVC low clouds with bases 1500-2500 ft MSL and tops to 2700 ft MSL will gradually increase and cover most areas west of the mountains by 11Z Thu. Areas of VIS 2-4 miles will occur in the valleys 08Z-16Z Thu. Most areas will clear 16Z-19Z Thu, except for local BKN conditions continuing near the beaches Thu afternoon. Low clouds will redevelop early Thu evening. Otherwise, clear skies with unrestricted vis through Thu evening. && .MARINE... No hazardous marine conditions are expected through Saturday morning. Gusty west to northwest winds late Saturday through Sunday are likely to generate hazardous boating conditions, especially in the outer waters. Current estimates for gusts is 25-30 knots, with the probability of gale force winds less than 20 percent. && .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...SUK/CO AVIATION/MARINE...Maxwell