Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA
Issued by NWS Seattle/Tacoma, WA
386 FXUS66 KSEW 170344 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 844 PM PDT Mon Sep 16 2024 .SYNOPSIS...Weak ridging over the area today for general benign conditions. A upper level trough and associated front will push through the region late Tuesday for some rain showers into Wednesday. Drier conditions into Thursday before unsettled weather likely returns to the area through the weekend. && .SHORT TERM /TODAY THROUGH THURSDAY/...Stilt imagery shoes high cirrus clouds moving across western Washington, as well as some low clouds and fog beginning to develop along the Pacific Coast and some of the mountain valleys. More high clouds look to filter in early tomorrow morning ahead of an incoming system. The marine stratus also gradually push inland tonight, as well as some patchy fog in the mountain valleys and foothills. Look for breaks in the clouds early tonight to potentially catch a glimpse at the aurora tonight. An upper level trough and associated front will start to approach the coastal areas by Tuesday morning and will start to spread rain showers inland by the afternoon. Latest ensembles show a strong jet jet digging southward which could slow down and weaken the front as it approaches western Washington. Regardless, there will be plenty of cloud cover around with light rain showers across the area. Low temperatures Tuesday night will hover in the 50s. The front will dissipate over the area into Wednesday with lingering showers, as weak northerly flow will keep our region somewhat dry into Thursday. High temperatures will continue to remain in the low to mid 60s. Mazurkiewicz/LH .LONG TERM /FRIDAY THROUGH MONDAY/...Confidence in the long term continues to wobble as ensembles attempt to agree on a solution. Latest guidance indicates a weak disturbance passing through the area on Friday which would keep showers in the forecast. The GFS continues to highlight an upper level ridge into the weekend, meanwhile the ECMWF highlights multiple systems with plentiful moisture into the beginning of next week. The latest trends have been pushing more towards the more wet solution, of multiple systems transversing across the Pacific Northwest, which could really open up the door to fall. Will keep chance of showers in the forecast for now and will see how the models evolve. Mazurkiewicz && .AVIATION...Light northerly flow aloft will increase westerly tonight as an upper trough and associated frontal system moves towards the area. Generally VFR cigs this evening with high clouds. Areas of low stratus are developing along the immediate coast this evening. Generally IFR/LIFR stratus will spread inland along the immediate coast tonight, with MVFR/IFR cigs for the interior by early Tuesday morning (reaching most interior areas between 11-14z). MVFR/IFR cigs are expected Tuesday morning with cigs lifting towards high-end MVFR and potentially low-end VFR Tuesday afternoon, with continued low cigs for the coast. Light rain will also be likely, mainly along the Olympic Peninsula on Tuesday. Light winds tonight will increase S/SW on Tuesday. KSEA...VFR conditions with high clouds this evening. Stratus will spread into Puget Sound, including the terminal, early Tuesday morning (generally between 12-14z). MVFR cigs are expected into Tuesday afternoon, with approximately a 30% of IFR cigs between 14- 18z. Light winds will increase S/SW Tuesday morning. JD && .MARINE...A broad surface ridge remains centered well offshore with lower pressure over the interior. Onshore flow will increase somewhat this evening. Strongest winds expected in the central/east strait tonight, with high resolution ensembles continuing to show only a 15-20% chance of reaching small craft criteria. The surface ridge over the offshore waters will weaken tonight and a trough and associated front will shift into the coastal waters on Tuesday. This system is unlikely to generate any headlines. The trough will weaken as it gradually shifts southward into the Oregon coastal waters on Wednesday. High pressure rebuilds offshore late in the week before another front is expected over the upcoming weekend. 27/cook && .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...None. && $$