Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
279 FXUS66 KSGX 212056 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 156 PM PDT Fri Mar 21 2025 .SYNOPSIS... Weak high pressure will continue through Saturday with near to slightly above average temperatures. High pressure off the coast will strengthen by Sunday and Monday, leading to much warmer weather away from the coast. Cooling will begin by the middle of the week, with temperatures nearing average by the end of next week. The marine layer will be deep enough to support some low clouds and patchy fog at times Saturday and Sunday mornings, the marine layer will become deeper as the troughing pattern takes over by the end of the week as cooler and breezier weather occurs. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Weak high pressure expanding from Hawaii to the coast of Baja will maintain its presence through Saturday, with light onshore flow and highs at the coast near average and 5 degrees above average inland. Patchy low clouds have been observed near San Diego. These will expand in coverage area near the coast later this evening into Saturday morning. Pressure heights lower slightly across the region by Saturday night, where the best chance of low clouds and fog will be with 5 to 10 miles of the coastline. By Sunday, the high over the ocean will move closer to the region and amplify. This will bring a warming trend to our area with Monday being the hottest day overall as the center of the high moves over us. Confidence is high that temperatures well into the 80s will occur for inland valleys west of the mountains. Parts of the Inland Empire have the best chance to break the 90 degree mark. Heights fall by Tuesday as a kink in the ridge crosses the region, this will let temperatures fall slightly but still very warm across inland areas. This will be the hottest day overall across the lower deserts, with confidence moderate to high on temperatures rising over 95 degrees. The ridge begins to depart on Wednesday as a large trough moves into the West Coast. This will bring greater onshore flow, cooling areas west of the mountains first on Wednesday then all of SoCal by Thursday. Thursday will see highs below 90 across the lower deserts and below 80 across the high desert and west of the mountains; mountain areas will see highs in the 50s and 60s. This trough will bring breezier conditions as well. The main axis of the trough will move over our region sometime around Thursday, NBM has the highest chances (30-60% chance) of winds being greater than 40 MPH across the mountains and deserts. Ensemble model clusters are still a bit out of agreement on the exact pattern later next week, but the general outlook is weak areas of high and low pressure moving through the area, leading to a continued quiet weather pattern. && .AVIATION... 212100Z...Coast...FEW-SCT high clouds AOA 25000 ft MSL and unrestricted VIS through tonight. There is a 30-40% chance of low clouds developing along the immediate coast after 03z this evening. By 12z, KSAN has the best chance (~60%) of seeing patchy CIGs. If CIGs develop, bases 1000 ft MSL or less are expected. Any clouds that make it ashore will clear by 18z Saturday. Valleys/Mountains/Deserts...FEW-SCT high clouds AOA 25000 ft MSL and unrestricted vis through Saturday afternoon. && .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...Munyan