971 FXUS66 KSGX 270436 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 936 PM PDT Sat Apr 26 2025 .SYNOPSIS... Cool and cloudy weather is expected through today, with light showers and mountain snow. There will also be strong southwest to west winds, strongest through mountain passes into deserts, through late this evening. Fair and warmer weather will follow most of next week, with the usual coastal clouds during the nights and mornings. Temperatures will then cool off again late next week into the weekend. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... No significant changes to the forecast this evening as the previous forecast remains on track. Light showers will continue to move across the area, but no additional significant precipitation amounts are anticipated. Previous discussion... .SHORT TERM... A low pressure system aloft is currently just west of Point Conception, and is driving a cold front west through the area, bringing light rain showers, mountain snow, possible afternoon thunderstorms, and gusty southwest to west winds. Rain totals for this event (or liquid equivalent above the snow line) will be from about 0.05" to a third of an inch for coastal and valley areas, a couple of hundredths to about a tenth of a inch for the western high desert, and 0.25" to 0.75" for most areas in the mountains with up to an inch locally on the windward slopes of the San Bernardino and San Gabriel mountains, most of which will fall as snow. Snow levels with the frontal precipitation band currently making its way through the region this afternoon are generally be between 5000 and 6000 feet, before dropping to 4500 to 5000 feet this evening as showers become isolated. Wet, heavy snow totals of up to 5 inches in the San Bernardino Mountains, up to 3 inches in the Riverside Mountains, and up to an inch or so in the San Diego Mountains is expected between now and Sunday afternoon above 5500 feet. The Coachella Valley and San Diego deserts, meanwhile, will continue to largely miss out on any precipitation, but will continue to see gusty winds through this evening. Southwest to west winds are 25 to 40 mph over the mountains and deserts, with gusts to 55 mph. As per usual, strongest winds are through areas like the Banning/San Gorgonio Pass on I-10 and through Walker Canyon on I-8, leading to difficult driving conditions, especially for high profile vehicles. The main low pressure system along with the front pass to the northeast this evening, bringing an end to widespread precipitation but with lingering showers overnight. Showers taper off from the northwest to southeast overnight, lingering in San Diego County longest through Sunday morning. Weaker low pressure remains aloft into early next week, and lingering moisture and weak lift could result in a few pop up showers over the mountains late Sunday afternoon, but with the moisture source effectively cut off the remainder of the region will see dry weather. This will result in continued cooler than average temperatures region- wide through Monday, however, albeit slightly warmer than today will be. && .LONG TERM... Tuesday Apr 29 through Saturday May 03... Weak high pressure builds in aloft Tuesday and part of Wednesday, bringing noticeably warmer (near-average) temperatures, dry weather, and average afternoon breezes. This will also make the nightly marine layer low clouds shallower and more confined to coastal areas. While some divergence in ensemble model solutions exists Thursday onwards, the flow looks to split Thursday, with high pressure over the northwest U.S. and low pressure aloft over southern California. This won`t have much effect besides a slight cooling along the coast Thursday that will start to spread inland Friday and Saturday as larger scale troughing settles into the western U.S. Near average temperatures region-wide will dip slightly below average for areas west of the mountains Friday, then below average temperatures are likely region-wide Saturday. The marine layer will deepen and spread farther inland each night and morning for the latter half of the week. Deeper low pressure looks likely to move in Sun-Mon. Currently a fair number of the members of both the GEFS and ECMWF ensemble are showing light rain for around Sunday and early the next week, but confidence this far in advance is fairly low. && .AVIATION... 270400Z....Coasts/Valleys/Coastal Mountain Slopes...SCT-BKN clouds with bases 3000-6000 ft MSL will continue through Sun evening with higher terrain locally obscured. Local VIS 3-5 miles and local BKN-OVC bases 2000-3000 ft MSL will occur in -SHRA through 20Z Sun, but most VIS will remain unrestricted below the clouds. Mountains/Deserts...Occasional west winds with gusts 20-35 kt will continue through Sun evening, mainly from the mountain crests east through the desert mountain slopes and locally into the deserts, including below mountain passes. SCT -SHRA/-SHSN will occur in the mountains through Sun with occasional mountain obscurations in clouds. Some clearing will occur Sun evening. && .MARINE... No hazardous marine conditions are expected through Thursday. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...Winter Weather Advisory until 11 PM PDT this evening for Riverside County Mountains-San Bernardino County Mountains. Wind Advisory until 11 PM PDT this evening for Apple and Lucerne Valleys-San Diego County Deserts-San Gorgonio Pass near Banning. Beach Hazards Statement from 6 AM PDT Sunday through Wednesday evening for Orange County Coastal Areas. PZ...None. && $$ PUBLIC...Suk AVIATION/MARINE...Maxwell