A cooling trend will ensue from Friday into the weekend, most notably for the mountains and western valleys, as high pressure weakens over the region. An area of low pressure from the north will move over the Desert Southwest by the middle of next week. Though the path of this system remains uncertain, chances of precipitation are in the forecast.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
Offshore flow continues to subside with gusts mainly below 30 MPH across the mountains and adjacent foothills. High clouds this afternoon will begin to scatter out tonight with patchy shallow low clouds nearing the coast at times. A weather system currently in the Pacific Northwest will continue to push inland over the western part of the country, helping to weaken the area of high pressure over our region through the weekend. This will lead to cooler weather with greater onshore flow. By the weekend, most areas will be in the 60s and 70s, with 50s across areas above 5,000 feet. Chances for fog will increase near coastal areas into the weekend as well as the marine layer deepens.
A low pressure system will move across the Great Basin by Sunday and Monday, which will lead to a slight increase in offshore winds by Monday. Depending on the strength of this pressure gradient, temperatures may climb into the mid or even upper 70s for valleys west of the mountains. A secondary weather system will move in from the north around Wednesday of next week. Model projections show quite a varied array of where the system will go. Some projections point to a more inland scenario, where we would remain dry with Santa Ana winds. Others point to a wetter scenario, where the system moves closer to our area or off the ocean. Nbm shows increasing chances for precipitation around 15-30% by Wednesday and Thursday of next week. Continue to keep an eye on the forecast as our confidence grows on the path of this weather system and how it could impact your area.
272030z. Coasts/Valleys, VFR prevailing with SCT-BKN high clouds AOA 20,000ft MSL. Patchy low clouds develop offshore tonight, with a moderate chance (35-50%) of brief impacts at KSAN with bases around 500-800ft MSL and a 30% chance at KSNA or KCRQ. Highest chances for impacts will be between 11-17z Fri. Localized VIS reductions down to 3-5SM possible during this time as well, with possibly lower for coastal terrain. Any clouds that made it ashore will filter back to the coast by 18-19z.
.Mountains/Deserts, VFR conditions expected through the TAF period. High clouds SCT-BKN AOA 20,000ft MSL prevailing through tonight.
Ca, None. PZ, None.
