008 FXUS66 KSEW 160946 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 246 AM PDT Thu May 16 2024 .SYNOPSIS...An upper level trough will dip down south from the British Columbia today for cooler temperatures and a chance for showers mainly in the northern portions of our region. Unsettled weather looks to continue through the weekend and into early next week, with cooler temperatures and more chances of showers. && .SHORT TERM /TODAY THROUGH SATURDAY/...An upper level trough will continue to move southward from British Columbia through this afternoon, with a weakening cold front swinging through western Washington into this evening. A chance of showers will return throughout the day with breezy winds at times and slightly cooler temperatures. Moisture looks mostly confined throughout the Northern Cascades, with the best chance of showers being primarily there. As the aforementioned cold front swings through the area, onshore flow will also increase behind the front, leading to breezy winds at times throughout the lowlands. Latest hi-res guidance suggests a convergence zone to develop post-frontally near western Skagit and Snohomish counties later this evening.. with likely higher precipitation amounts within the convergence zone. Snow levels look to drop around 3000 to 3500 feet as well, with some light snow accumulations in the higher peaks in the backcountry. High temperatures this afternoon will be around the mid 60s for the interior, and in the upper 50s for locations near the coast and areas of water. The upper trough axis will swing directly above western Washington on Friday, with some leftover showers staying in the higher terrain in the Cascades. Most of the interior should remain dry with clouds breaking up for some. Temps will continue to remain in the mid 60s. A weak shortwave will pulse through the region on Saturday, keeping the unsettled weather trend going with another chance of showers for the area. Precip looks light and will likely continue to stay focused in the Cascades. .LONG TERM /SUNDAY THROUGH WEDNESDAY/...Ensemble guidance and clusters are in general agreement for troughing to continue over the Pacific Northwest, with several disturbances tracking across our region in the long term. Temperatures will remain at or just below average through Wednesday, with light shower chances likely each day, although shower chances look spotty in coverage. Mazurkiewicz && .AVIATION...West to northwesterly flow aloft throughout the day today as an upper level trough starts to dip into W WA. Surface flow generally southerly throughout the day with lighter winds this morning before becoming gusty this afternoon and evening. Cigs already feeling impacts from incoming frontal system with a mix present over the area...seemingly equal parts VFR, MVFR and IFR. IFR conditions favoring the south Sound area as well as HQM and PAE. MVFR present along most of the remaining Sound obs. Most northern terminals are still reporting VFR conditions. Expect cigs to continue to lower as the day progresses with most sites bottoming out in MVFR to IFR conditions by 12-15Z and remaining there for the morning. Some improvement in the afternoon with most spots recovering to high-end MVFR in the afternoon with VFR conditions returning this evening and tonight. The exception will be in locations that tend to favor lower cigs such as HQM, OLM where recoveries should nudge them just into low-end MVFR. Showers will be possible today, but favored terminals look to be HQM and BLI. Remainder may see some limited activity, but likely falling more in the range of a PROB30 group than any other classification. KSEA...MVFR cigs in place and will likely lower a little bit more by 12Z down to around 1500 ft. Will start to see some lifting this afternoon to around 2500 before returning to VFR conditions tonight. Above shower discussion applies. There is the prospect for some convergence zone activity, but current model data suggests it remains either north or east of the terminal. 18 && .MARINE...Breezy to windy conditions with the incoming frontal system will keep headlines in the marine forecast for much of today and possibly into Friday. While previous models suggested a brief break in the winds in the Strait this morning, data no longer supports that outcome. As such, decided to not get fancy with the forecast and simply extended inherited headlines to cover at least most of the event expected today. Inherited SCA for coastal waters looks good and will remain untouched. Otherwise, remaining interior waters look to reach into SCA criteria at varying times and have staggered their headlines accordingly. Headlines in the Strait will likely need extension into Friday, but will leave that for following shifts. Winds expected to ease for most waters, save perhaps the outer coastal waters this weekend into early next week. Seas will hold around 4 to 6 ft today before increasing 8 to 12 ft from Friday into the weekend, reducing to 6 to 8 ft early next week. 18 && .HYDROLOGY...The daily hydrology discussion has ended until the start of the next rainy season; it will only be updated as needed. && .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...Small Craft Advisory from 5 PM this afternoon to 11 AM PDT Friday for Admiralty Inlet-West Entrance U.S. Waters Strait Of Juan De Fuca. Small Craft Advisory until 11 AM PDT Friday for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca-Northern Inland Waters Including The San Juan Islands. Small Craft Advisory from 5 PM this afternoon to 5 AM PDT Friday for Puget Sound and Hood Canal. Small Craft Advisory from 2 PM this afternoon to 11 AM PDT Friday for Coastal Waters From Cape Flattery To James Island 10 To 60 Nm-Coastal Waters From Cape Flattery To James Island Out 10 Nm-Coastal Waters From James Island To Point Grenville 10 To 60 Nm-Coastal Waters From James Island To Point Grenville Out 10 Nm-Coastal Waters From Point Grenville To Cape Shoalwater 10 To 60 Nm-Coastal Waters From Point Grenville To Cape Shoalwater Out 10 Nm. && $$