Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
091 FXUS66 KSGX 040439 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 930 PM PDT Fri May 3 2024 .SYNOPSIS... Mostly cloudy cool weather will prevail this weekend with gusty winds in the mountains and deserts and periods of showers over and west of the mountains. Southwest to west winds will increase in strength through the day Saturday, peaking Saturday night and early Sunday. Some drizzle may occur Saturday morning, but the best chances of accumulating rain will be Saturday night and early Sunday. Dry and warmer conditions will prevail Monday through most of next week. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Low clouds along the coast were already spreading into the valleys at mid-evening, with stratus covering all valley areas by late tonight with some drizzle forming as well. Current progs suggest the timing of most of the measurable rain to be 11 PM Saturday through 9 AM Sunday, generally from northwest to southeast with the cold front associated with the system. Rainfall still is forecasted to be mostly light, under 1/4" except local amounts over 1/2" in a few coastal-slope locations of the mountains. Like is typical with spring systems, the wind will be a factor, with a few gusts around 70 MPH Saturday night through San Gorgonio Pass and along a few of the desert mountain slopes. From previous discussion... A low pressure system is on track to move inland through California on Saturday night and dig into the Great Basin on Sunday. This system will bring cooler, cloudier, windier (in the mountains and deserts), and wetter conditions (in and west of the mountains) to Southern California this weekend. Southwest to west winds will begin to increase Saturday afternoon, peaking in strength Saturday night into Sunday, gradually diminishing into Sunday night. Winds will be strongest on the desert mountain slopes, through passes, and into portions of the deserts. Peak gusts of 55 to 65 mph expected. There is a 30 to 40 percent chance that a few isolated gusts to 70 mph are possible in wind prone locations on the desert foothills of the San Bernardino mountains and near the San Gorgonio Pass late Saturday night. Winds will gradually weaken into Sunday night. For much of next week, a broad troughing pattern over the United States will enhanced the onshore pressure gradient, bringing periods of breezy westerly winds to the mountains and deserts each afternoon and evening. A weak coastal eddy is expected to help deepen the marine layer overnight. This could result in patchy drizzle for the coast and valleys tonight into Saturday morning. The best chance for showers and accumulating rain is late Saturday night into Sunday morning. Shower coverage will be scattered with mostly light amounts expected to accumulate. A few hundredths to a tenth of an inch of rain are expected for the coast and valleys. One-quarter to locally one-half inch expected on the coastal slopes of the mountains with the greater amounts most likely on the coastal slopes of the San Bernardino County mountains. A trace of snow is expected above 7000 ft. This will be a quick moving system and dry conditions are expected by early Sunday afternoon. Highs Saturday are expected to be 3 to 5 degrees below average for the coast and valleys, and near average for the deserts. Sunday will be even cooler, especially for inland areas with highs 10 to 15, locally up to 20 degrees below average for the valleys, mountains, and deserts. Cold conditions expected Monday morning, especially in the High Desert where lows are forecast to fall to the mid to upper 30s. The highs on Monday will make up for the cool conditions Sunday and Monday morning, with temperatures as much as 10 to 15 degrees warmer than Sunday for the mountains and High Desert. Conditions are expected to gradually warm into the end of next week. && .AVIATION... 040350Z...Coasts/Valleys/Foothills...Patchy low clouds with bases 2000-2500 FT MSL are occurring this evening. Clouds will fill in across the coast/western valleys through 07z Sat, reaching the Inland Empire/foothills after 10z Sat. Bases may lower a few hundred feet overnight. Terrain obscurations where low clouds and terrain intersect. Scatter out 17z-20z Sat across the valleys, with coastal sites seeing intermittent cigs through the afternoon. Mountains/Deserts...W-SW winds developing after 20z Sat with the strongest winds occurring after 00z Sun. Expect W-SW winds 20-35 kt with gusts of 45-60 kt. Areas of MOD-STG up/downdrafts and LLWS over/east of mtns. Otherwise...Clear skies with unrestricted VIS will continue into Sat morning, with increasing high clouds AOA 15,000 FL MSL on Sat. && .MARINE... No hazardous marine conditions are expected through Saturday morning. Gusty northwest wind gusts of 25 to 30 knots will occur Saturday evening through Sunday evening, which will generate hazardous boating conditions, especially in the outer waters. Northwest wind gusts up to 20 knots will be possible over the outer waters each afternoon and evening Monday through the middle of next week. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...Wind Advisory from noon Saturday to 8 PM PDT Sunday for Apple and Lucerne Valleys-San Bernardino County Mountains-San Gorgonio Pass Near Banning. Wind Advisory from 3 PM Saturday to 8 PM PDT Sunday for Coachella Valley-Riverside County Mountains-San Diego County Deserts-San Diego County Mountains. PZ...Small Craft Advisory from 3 AM to 10 PM PDT Sunday for Coastal Waters from San Mateo Point to the Mexican Border and out to 30 nm. Small Craft Advisory from 6 PM Saturday to 3 AM PDT Monday for Waters from San Mateo Point to the Mexican Border Extending 30 to 60 nm out including San Clemente Island. && $$ PUBLIC...Maxwell (Update)/CO (Previous Discussion) AVIATION/MARINE...EA