Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
180 FXUS66 KSGX 280855 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 155 AM PDT Sun Apr 28 2024 .SYNOPSIS... Warm and dry weather will continue through much of the upcoming week. The marine layer will keep low clouds and fog closer to the coast and western valleys each night and morning. Mountains and deserts will be breezy over the next few days with a chance for weak Santa Ana winds to impact valleys west of the mountains by Thursday. Slight cooling and breezy weather for inland areas may occur by next weekend. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... A weak coastal eddy is helping low clouds sneak near the coast this morning. Latest WRF/HRRR guidance show this regime occurring over the next few days, through Tuesday, which will prompt low clouds and patchy fog within 10 miles of the coast. Today will be noticeably warmer, especially away from the immediate coast with highs near 80 across the Inland Empire and low 90s across the Coachella Valley and Anza Borrego Desert. Warming will continue by Monday and Tuesday as weak high pressure prevails over the region, with many areas along and west of the mountains getting into the mid/upper 60s at the beaches and higher elevations to lower 80s across the Inland Empire and High Desert. NBM indicates breezy west winds each afternoon/evening across the mountains and deserts with gusts near 20-30 MPH. A passing trough across the Pacific Northwest will tighten the pressure gradient over our region, leading to increased onshore flow and a deeper marine layer. Temperatures will remain close to slightly above average. Ensemble clusters are still in disagreement on the position of where this trough goes, but depending how far south it goes across the Great Basin, it will generate Santa Ana winds. For now, the winds look weak with low probabilities of winds greater than 30 MPH per latest NBM guidance. Another trough may form over the western U.S., leading to more cooler and breezier weather by later next week with continued dry weather. && .AVIATION... 280850Z...Coast/Valleys...10Z-16Z...areas BKN015-025 within 10 miles of the coast, about 50-70 percent chance for CIG impacts at KSAN and KCRQ. Less than 20 percent chance for CIG impacts at KSNA. Mostly clear after 16Z. Mountains/Deserts...Mostly clear through today. Gusty northwest winds 15-35 kt through 12Z, with weak up/downdrafts and LLWS over and east of the mtns. && .MARINE... No hazardous marine conditions are expected through Wednesday. && .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...APR AVIATION/MARINE...PG