Expires:No;;671709 FXUS66 KSGX 051553 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 853 AM PDT Sun May 5 2024 .SYNOPSIS... Light rain showers across central San Diego County will diminish over the next hour or two, giving way to a cool day with passing clouds. Strong winds over the mountains and deserts will continue through this evening. Dry weather with slow warming will prevail through most of the upcoming week. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Update... A 543 DM low is progressing into the Great Basin this morning, and a shortwave is rounding the base of the trough over the Mojave Desert. A weak front produced generally light rain showers earlier this morning, with most locations across the coast and western valleys picking up a few hundredths of an inch to a quarter of an inch of rain, and higher amounts along the foothills and mountains. Clouds are clearing out pretty quickly behind the front, with most coastal and valley areas seeing only passing clouds. Mountain waves are clearly visible on satellite imagery, signifying strong winds over the mountains and desert slopes. Peak wind gusts of 50-55 mph will occur through this evening before diminishing. Today will be the coolest day of the week for most areas, with highs topping out 3-6 degrees below normal across the coast and western valleys, and 10-20 degrees below for the foothills, mountains and deserts. Much warmer conditions are expected tomorrow. Previous Discussion (Issued 253 AM PDT Sun May 5 2024)... .SHORT TERM (Today-Tuesday)... Once the front moves through, the remainder of the day will be partly cloudy and cool. Highs will reach the 60s for the coastal areas and valleys, 40s in the mountains, upper 50s to low 60s in the high desert, and mid to upper 70s in the low deserts. The upper level low moves out on Monday with drier northwest flow into Tuesday. Monday will be significantly warmer, followed by minor warming on Tuesday, though still a few couple degrees below normal. Breezy west winds develop in the mountains and deserts each afternoon into late night, though are forecast to remain below advisory strength. Some patchy marine layer low clouds will develop along the coast each night, especially on Tuesday with the development of a coastal eddy. The marine inversion will be fairly weak though, so expect decent clearing each day even at the coast. && .LONG TERM (Wednesday-Saturday)... Minor warming continues into Wednesday as we remain under weak cyclonic flow wedged between the upper ridge off the West Coast and a large upper low over the northern Great Plains. Both deterministic and ensemble models are coming into better agreement with the evolution of this pattern into the latter half of the week. A positively-tilted short wave on the back side of this low will amplify late Wednesday, eventually splitting from the parent low and retrograding southwestward into Thursday and Friday. There is the potential for weak offshore flow Wednesday morning as the short wave drives south and surface high pressure begins to build over the Great Basin. There are still differences in the placement and strength of the low late in the week, resulting in increasing spread in the temperature forecast. Since models have trended to the further west solution, forecast now has temperatures remaining fairly steady/not as warm for the latter half of the week. Marine layer low clouds will continue for the coastal areas and portions of the valleys each night and morning, potentially deepening and spreading further inland next weekend if the upper low continues to drift west or southwest as some ensemble members and the deterministic models suggest. && .AVIATION... 051530Z...Coasts/Valleys/Foothills...-SHRA continues across southeastern San Diego County this morning. Skies will briefly clear this morning followed by FEW-SCT clouds, locally BKN-OVC with bases 2500-3500 FT MSL through this afternoon and early evening. Skies clearing generally between 06-09z tonight. Some patchy low clouds possible overnight but CIGs are unlikely. W-NW winds increasing later this morning and afternoon, with peak wind gusts of 25-30 kts possible along the immediate coast. Mountains/Deserts...Expect another round of strong W-SW winds 20-35 kt with gusts of 45-60 kt after 18Z. Areas of MOD-STG up/downdrafts and LLWS over/east of mtns. SCT-BKN clouds at/abv 10000 ft MSL through this evening. && .MARINE... Northwest winds gusting 25 to 30 knots will continue through this evening, which will generate hazardous boating conditions, especially in the outer waters. Northwest winds gusting up to 20 knots will be possible over the outer waters each afternoon and evening for 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 until 8 PM PDT this evening for Apple and Lucerne Valleys-Coachella Valley-Riverside County Mountains-San Bernardino County Mountains-San Diego County Deserts-San Diego County Mountains-San Gorgonio Pass Near Banning. PZ...Small Craft Advisory until 10 PM PDT this evening for Coastal Waters from San Mateo Point to the Mexican Border and out to 30 nm. Small Craft Advisory until 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...EA/SS AVIATION/MARINE...Adams