Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
982 FXUS66 KSGX 021557 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 857 AM PDT Thu May 2 2024 .SYNOPSIS... Periods of low clouds and fog are expected each day west of the mountains, most widespread in the nights and mornings. A passing weather system to our north will increase cloud coverage for inland areas this weekend. That system will also bring gusty winds to the mountains and deserts, cooler conditions, and periods of showers to areas over and west of the mountains. Drier and warmer conditions are expected through the middle of next week. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... A robust eddy is spinning along the coast this morning, which is helping marine layer low clouds and fog surge inland. At 8 AM, low clouds continue to surge inland, almost filling in the coastal basin. The inversion on the 12Z sounding is a few degrees stronger than yesterday`s (about 8 degrees vs 5 degrees yesterday). Low clouds should eventually clear the valleys but could stick along the beaches this afternoon. Low clouds are expected to spread into much of the coastal basin overnight into Friday morning and again Friday night into Saturday morning. A low pressure system will move into the Pacific Northwest Saturday, before digging south in the Great Basin Sunday. This will increase onshore flow for Southern California this weekend and as a result cloud coverage (especially for the valleys and mountains) will be more persistent, high temperatures will take a dip, winds will increase, and areas of showers are expected. Periods of gusty westerly winds over the mountains, through passes, and into the deserts will be the main weather hazard. Winds will begin to increase Saturday afternoon, peak Saturday night into Sunday, before slowly decreasing into Sunday evening. For Saturday night into Sunday morning along the desert slopes of the mountains and adjacent desert areas, peak gusts of 55 to 65 mph are expected. Periods of mostly light precipitation are expected for places in and west of the mountains. Coverage of the precipitation will be showery with the best chances of showers in the mountains, the Inland Empire, and west of the mountains in San Diego County. This is a fast moving system and current timing has shower activity occurring Saturday night into Sunday morning. Rainfall totals of a one-tenth inch or less are expected for the coast and valleys with up to one- quarter inch of rain for the coastal mountain slopes. A trace of snow is possible above 7500 ft. High temperatures will be fairly similar between today and tomorrow, with highs near to slightly above average. Cooling conditions are expected Saturday, with further cooling expected on Sunday. On Sunday highs will be 10 to 15 degrees below average for inland areas. Monday will be dry and much warmer, around 5 degrees warmer at lower elevations to 8 to 12 degrees warmer for the mountains with not much change for Tuesday and Wednesday, generally a few to around 5 degrees below average. && .AVIATION... 021530Z...Coasts/Valleys...Low clouds with bases 1400- 1800 feet MSL, tops to 2500 feet and inland vis 1-5SM will gradually scatter out by 17-19Z, but patchy and intermittent BKN clouds could linger near the coast thereafter. Low clouds spreading back inland after 02Z with bases 1400-2000 feet MSL with a similar cloud coverage inland. Scatter out Friday 17-19Z. Otherwise, clear skies with unrestricted vis through Friday morning. && .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. && .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 AVIATION/MARINE...MM