FXUS66 KSGX 152152 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 152 PM PST Thu Feb 15 2024 .SYNOPSIS... Dry and fair weather will continue through the weekend. An incoming Pacific storm system will bring cool and wet weather Monday through Wednesday. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... .SHORT TERM (Thursday through Sunday)... Temperatures are warming right on schedule across SoCal on this beautiful day with 50s and 60s for many locations, nearing 70 from Palm Springs to Ocotillo Wells. Onshore flow has taken over this afternoon with gusts near 20-30 mph across the high desert and through the San Gorgonio Pass. A ridge off the coast will peak in strength on Friday and Saturday, leading to warmest days over the next week. Mountain areas will see highs in the 50s and 60s, 60s and 70s west of the mountains and higher desert, along with nice and warm upper 70s for the lower deserts. The marine layer will continue to become shallower tonight into Friday night, where clouds will be mainly confined near the coast and western portions of the Inland Empire. A large trough offshore will move closer to the State this weekend, where the first wave of moisture will move in near the Bay Area. We will remain dry from this first system, but cooler temperatures and breezy conditions across the mountains and deserts will result from this, especially on Sunday. && .LONG TERM (Monday through End of Next Week)... The large area of low pressure will slowly move into our area by early next week, where model timing is in better agreement of rain showers starting near the LA County line Sunday evening. The speed of the system is more uncertain, so areas in San Diego County may not see rain until Monday morning or even Monday night. Rain will be light across SD County, but more moderate in intensity across northern areas along and west of the mountains. This day may be the heaviest across this area as ensemble members are honing in on this time frame, as well as a defined IVT moisture plume pushing through the area with chances for 40-60% chance of PWAT over 1 inch. Onshore flow will be greatest on Monday ahead of the low pressure system. Increased winds across the mountains and deserts. Latest hi-res guidance and ensemble members show modest chances for wind gusts to be greater than 30 mph at times on Monday across the high desert and desert slopes. Showers will continue overnight Monday into Tuesday, where the system will slowly push inland, spreading greater precipitation southward and eastward into the lower deserts and the rest of San Diego County. As it does so the system will continue to weaken, so amounts will be lighter across San Diego. Colder air aloft behind the system will have the capability for increased areas of instability, so we will continue to monitor the forecast for thunderstorm potential Tuesday night or Wednesday morning. In terms of rainfall amounts, the chance for 1 inch or more of rainfall from Monday through Wednesday has gone slightly down since yesterday's forecast. Probabilities of greater than 1 inch include: 30-45% OC/Western Inland Empire, 45-60% San Bern Coastal slopes, 10-20% eastern Inland Empire and western SD County. Snow levels will be high for this storm, mainly over 6,500 feet where confidence is moderate for the Big Bear area to receive 1-3 inches of total snowfall. Per latest forecast amounts above, this storm will not be nearly as impactful as those we have seen over the last month. Localized flooding cannot be ruled out though, especially for areas across the western LA Basin. The storm system will push east on Wednesday with drying occurring late Wednesday into Thursday. This may be brief, as cluster model analysis is pointing to yet another area of low pressure coming into the vicinity of SoCal, so we will have to wait and see how that pans out! && .AVIATION... 152040Z...Coast/Valleys: SKC with unrestricted VIS this afternoon. Low clouds increasing in coverage after 03Z Friday. Expect bases 2000-2500 ft MSL. Cig impacts at coastal TAF sites likely 06Z-17Z Friday. Mountains/Deserts: SCT250 with unrestricted VIS through tonight. && .MARINE... No hazardous marine weather conditions through Sunday. A Pacific storm will bring a large, long-period swell Sunday, strengthening southerly winds Sunday night and Monday, and scattered showers Monday and Tuesday. && .BEACHES... A west swell of 8-10 feet with a period of 16-18 seconds) will arrive Sunday morning, producing surf of 7-10 feet or more on west- facing beaches. Tidal overflow and minor beach erosion is possible Sunday and Monday during the early morning highs tides of 5.0 ft. A second long-period swell could bring more high surf Tuesday. Stay tuned for updates. && .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...APR AVIATION/MARINE...PG