050 FXUS66 KSGX 060924 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 224 AM PDT Fri Jun 6 2025 .SYNOPSIS... A deep marine layer with patchy drizzle this morning. Warmer with the marine layer becoming more shallow this weekend into early next week. Heat will peak on Tuesday with gradual cooling through the end of the week. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Marine layer low clouds continue to spread into the inland valleys this morning with mostly clear skies elsewhere. Light precipitation has been reported in northwestern San Diego County this morning with patchy drizzle likely to continue through mid morning. Otherwise a very June Gloom day along the coast and high temperatures near normal today. Some lingering mid-level moisture will be in place for some scattered cumulus development over the mountains and a 10% chance of showers over the highest peaks of the San Bernardino Mountains during the afternoon. Surface high pressure will slowly build in from the southeast on Saturday with a cut-off low lingering off the Central CA coast. A warming trend will begin, continuing into early next week as the upper high shifts westward to our south and then amplifies to our southwest. This will also cause the marine layer to become more shallow, with low clouds covering only the coastal areas and far western valleys by Monday. For Tuesday, there is a 15-20%chance of high temperatures of 100 degrees or more in the far inland portions of the Inland Empire and a 25-50% chance in the lower elevation portions of the high desert. There is a 10-25% chance of highs of 110 or more in the low desert, locally up to 40% at Palm Springs. In general highs will be around 5-10 degrees above normal Monday and Tuesday with moderate HeatRisk in the inland valleys and deserts. The upper level high begins to weaken on Wednesday as a short wave trough moves by to the north, then the high shifts westward with an upper trough developing along the West Coast Thursday and Friday for greater cooling and a deepening of the marine layer. Some ensemble members show a much weaker trough and therefore less cooling during this period, but it only accounts for about 13% of the ensemble space. && .AVIATION... 060930Z....Coast/Valleys...Low clouds based 1200-2000 ft MSL with tops to 2500-3000 ft are in place over most of the coastal basin. The northern IE should fill in over the next few hours. Areas of -DZ bringing periodic vis restrictions 2-5 SM in BR and lower cigs to 700-900 ft MSL. Clouds gradually clearing from inland areas, coastal Orange County, and coastal northern San Diego County 16-19Z Fri. However, coastal areas from KCRQ southwards and to about 10 miles inland in San Diego County will likely remain BKN all day once again. Clouds will quickly push into inland San Diego County after 00z Sat followed by Orange County and the IE after 04z. However, there is a 30% chance that the IE does not fill in completely due to a slight lowering of the cloud layer. Mountains/Deserts...Mostly clear through Friday night. FEW-SCT cumulus based at 10,000ft MSL will form 19Z Fri-01Z Sat over northern mountains and high desert. && .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...SS AVIATION/MARINE...KW