333 FXUS66 KSGX 130418 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 918 PM PDT Thu Jun 12 2025 .SYNOPSIS... Subtle warming will occur across inland areas through the weekend as an area of high pressure strengthens over the desert southwest. The marine layer will remain quite consistent, with night and morning low clouds near the coast into the western valleys. Weak troughing and ridging across the Southwest next week will lead to minor fluctuations in high temperatures and the marine layer. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... This evening...The marine layer is a little deeper than yesterday evening, at about 2000 ft. There was some cooling above the inversion, making it a little weaker than yesterday. Low clouds have already spread about 10-15 miles inland and will likely spread farther inland than last night as sfc pressure gradients trend a little stronger onshore. This afternoon, high temperatures approached 110 degrees at some locations in the lower deserts, and reached the low 90s in some valley locations...mainly in the IE. From previous discussion... An area of high pressure over Baja California will strengthen and push northward across the Southwest by the weekend. 850 mb temperatures will increase to around 30C by Sunday. As a result of this, warmer temperatures can be expected away from the coast with highs 5 to 10 degrees above normal. High temperature probabilities have gone slightly downward over the past couple of days, but we will still be seeing hot weather across inland valleys and desert areas, with moderate to locally high heat risk. There is high confidence in seeing temperatures above 110 degrees in the lower deserts and moderate confidence in seeing highs reach 100 degrees for places in the Inland Empire and populous areas of the high desert. A weak trough will cross California early next week, which will aid in lowering temperatures closer to normal. Night and morning low clouds will still continue at the coast and western valleys. Another area of high pressure may gain strength by the middle of next week, which would lead to another subtle warm up. && .AVIATION... 120330Z....Coast/Valleys...Low clouds based around 0900-1600 feet MSL will continue to move inland throughout the evening, and eventually into the valleys early tomorrow morning, but not as extensively as the previous morning. Bases will continue to fall to around 500-1000 ft MSL with vis reduced 0-5SM over higher coastal terrain between these levels. Clouds clearing 15-17Z Fri for inland areas and 18-20Z for coastal regions. Clouds will again linger along the beaches, but with better chances for brief clearing at KCRQ (70%) and moderate chances at KSAN (40%). Clouds will begin to regather and fill back in from west to east tomorrow evening with very similar timing and cloud bases as they were this evening, mainly after 00Z Sat. Mountains/deserts...Mostly clear skies and unrestricted vis expected through tomorrow night. && .MARINE... No hazardous marine conditions are expected today through Tuesday. && .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...PG AVIATION/MARINE...Stewey