Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
272 FXUS66 KSGX 011006 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 306 AM PDT Sat Jun 1 2024 .SYNOPSIS... Night and morning low clouds will fill in the coastal basin each day into early next week. For this weekend, high temperatures will be a few degrees below average west of the mountains and a few degrees above average for the mountains and deserts. Conditions will gradually warm for much of next week, with warming most noticeable for inland areas Wednesday and Thursday, into Friday for the deserts. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... At 3 AM Saturday morning, satellite imagery was showing low clouds had filled in the coastal basin. Clear skies were being observed in the mountains and deserts. Weak troughing over the Southwest and the Catalina Eddy over the coastal waters will keep the marine layer deep into early next week. Expect clouds to fill in the coastal basin through Monday morning. Clearing is expected to the coast each afternoon, but there is low confidence in complete clearing at the beaches. The marine layer will become shallower into the middle and end of next week as heights rise with weak ridging. High temperatures through Monday are expected to be a few degrees below average for areas west of the mountains and a few degrees above average in the mountains and deserts. Highs for the next few days will be in the upper 60s to low 70s near the coast; upper 70s to low 80s for the valleys; the 70s in the mountains; low 90s in the High Desert; and 100-105 degrees in the low deserts. The aforementioned trough will enhance the onshore pressure gradient with west winds with gusting to around 25 to 40 mph expected each afternoon and evening in the mountains and deserts this weekend. Ridging is expected over the Southwest Tuesday through at least Friday. The warmest days of the week are expected to be Wednesday and Thursday for the Inland Empire and deserts, continuing into Friday for the deserts. While there is good consensus amongst models that a ridge will develop, there remains some spread in the placement of the ridge and the strength of the ridge. Additionally, there is some uncertainty surrounding how long the ridge will remain over the Western US. Current forecast closely follows the NBM and has the warmest days of the week Wednesday and Thursday for the Inland Empire, and Wednesday through Friday for the deserts. The ridge placement will also influence the depth of the marine layer and thus how warm the western valleys could get. Locations like Fullerton, Ontario, and Ramona, who`s high temperatures can be greatly influenced by the marine layer depth, are showing 8 to 9 degree temperature spreads between the warmest and coolest high temperature solutions on the ECMWF. The main take away is although there remains some uncertainty in the exact details, warm conditions are expected for the middle to end of next week away from the coast with at least moderate heat risk for portions of the Inland Empire and deserts. && .AVIATION... 010915Z...Coast/Valleys...Low clouds with bases 1200-1500 FT MSL are occurring across the coastal basin. Occasionally lower cigs of 700- 1000 FT MSL through 15z Sat. Reduced vis of 2-4 SM, locally below 1 SM where low clouds and terrain intersect. Scatter out across inland areas 16z-18z Sat, with only partial clearing at the coast. Clouds spreading back inland after 00z Sun. Mountains/Deserts...Clear skies with unrestricted VIS through tonight. W-SW wind gusts of 25-35 kt occurring 22z Sat-06z Sun. MOD up/downdrafts over/east of 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...CO AVIATION/MARINE...EA