Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA
Issued by NWS Seattle/Tacoma, WA
518 FXUS66 KSEW 162155 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 255 PM PDT Thu Oct 16 2025 .SYNOPSIS...A weak frontal system will move across the area tonight into Friday bringing light rain showers to the area. A stronger, wetter system will follow Saturday evening into Sunday, bringing gusty winds, lowland rain, and mountain snow to the area. A brief drying trend is expected on Monday, before unsettled conditions look to return Tuesday and continue through the rest of the week. && .SHORT TERM /TONIGHT THROUGH SUNDAY/...Recent satellite imagery shows mid to high level clouds streaming in ahead of an approaching system. This system is fairly weak and will spread light rain showers across the area, with showers moving in throughout the evening. QPF is pretty minimal so most areas may not even see rain, with only a few hundredths of an inch rain likely across the lowlands, which a quarter to a half an inch expected for the mountains. Increasing onshore flow into Friday will help develop a weak convergence zone across the Central and South Sound early Friday morning with showers tapering off by the afternoon for most of the area. High temperatures on Friday look to remain in the upper 50s to low 60s. A stronger and wetter system will cross over the region Saturday evening into Sunday, with widespread rain, breezy conditions, and mountain snow. Snow levels will rise upwards to 7000-9500 feet late Saturday evening as widespread rain will spread across most of the region. Winds will also become breezy, with gusts up to 20 to 30 mph at times throughout the overnight period. Winds will continue to remain breezy Sunday morning with showers continuing across most of the area - with areas along the Olympics and Cascades getting the bulk of the precipitation. Snow levels will fall back down towards 4500 feet in the wake of the front on Sunday, likely bringing some snow to the higher elevations of the mountains. The weekend system will bring QPF totals somewhere around a half an inch to an inch of rain across the interior lowlands, along with 1-3 inches along the coast and 2-4 inches for the Olympic and the Cascades. Though this event will be a good primer for area rivers, the antecedent dry conditions lend little concern for any flooding at this time. .LONG TERM /MONDAY THROUGH THURSDAY/...A transient upper ridge looks to move over the area on Monday which will help dry conditions out, with temperatures in the mid to upper 50s. Low confidence in the forecast starting on Tuesday as ensemble clusters still show a wide spread of solutions. A few weak systems look to move across the area midweek which would allow for showery and unsettled conditions. Will need to keep and eye on the intensity and exact placement of a ridge which could keep these systems away from western Washington, but for now, looks like unsettled conditions will continue at the end of the long term. Mazurkiewicz && .AVIATION...Mostly VFR this afternoon with areas of MVFR cigs generally west of the Puget Sound with increasing high and mid level clouds. Light showers will spread inland tonight as a weak frontal system crosses the region. Areas east of the Olympics are likely to be rain shadowed, while showers elsewhere will be light. Incoming moisture paired with onshore flow will generate widespread low stratus early Friday morning bringing most terminals to MVFR/IFR with areas of patchy fog. Conditions will slowly improve throughout the morning and afternoon Friday with the next system entering the region Saturday. Surface winds will generally remain out of the S/SW through the TAF period 5 to 12 kt. KSEA...VFR this afternoon with increasing mid level clouds. Conditions are favored to deteriorate early Friday morning, with a moderate chance (30% to 40%) of IFR ceilings developing around 1500 feet between 12z and 18z. Conditions will improve to VFR by the early afternoon Friday with mid level clouds. Surface winds will generally stay out of the S/SW 4 to 9 kt through Friday afternoon, before a brief switch to NE winds after roughly 19z. 15 && .MARINE...A weak frontal system will cross area waters tonight into early Friday with weak high pressure building in thereafter through Saturday morning. Post-frontal winds will increase through the Central Strait of Juan de Fuca on Friday, reaching Small Craft Advisory strength. A much stronger frontal system will move over area waters Saturday into Sunday, with numerous headlines expected across the outer and inner waters over the weekend. A series of additional frontal systems will cross the region through next week. Seas generally 4 to 6 feet will gradually build to 5 to 7 feet through Friday morning, then increase to 9 to 12 feet by Friday evening. Seas will remain elevated through the weekend, building as high as 19 feet across the outermost outer waters and 15 feet along the coastal waters on Sunday. Seas may be steep at times, especially Saturday night into Sunday. Seas are expected to fall below 10 feet briefly on Monday before building back to 10 to 16 feet through the remainder of the week. 15 && .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...None. && $$