FXUS66 KSEW 090318 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 818 PM PDT Thu May 8 2025 .SYNOPSIS...Dry and relatively warm weather will linger into Friday. The pattern will begin to shift late Friday setting the stage for a cooler, showery pattern for much of the weekend. A more organized frontal system looks to bring more widespread - even stratiform rain later Sunday into Monday. The pattern next week may be dominated by an offshore ridge, and cooler Spring like weather. && .SHORT TERM /TODAY THROUGH SATURDAY NIGHT/...Satellite imagery shows some more mid to high level cloud cover streaming in across western Washington this evening in association with a warm front well offshore. Overall, the forecast remains largely on track tonight with no updates needed to the short and long term public forecast. The previous discussion follows below, with updates made to the aviation section. 14 Upper level ridging settling into the area with dry and warm conditions coming along with it into Friday. High temperatures into Friday will reach to near 70 for many locations through the interior from King County Southward, and low to mid 60s elsewhere. The pattern will begin to shift Saturday with the upper level ridge starting to nudge eastward, ahead of an approaching upper level trough. This will set the stage for a cooler, showery pattern Saturday with highs in the 50s to the mid 60s. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/...The offshore upper level low is expected to shift more fully southward on Sunday - though ensembles vary a bit on the track and strength with some taking a more direct westward track, while others a more southeasterly path into Oregon. Either way Sunday looks to see more widespread shower activity - and a slight chance of thunderstorms later in the afternoon and evening. Grand ensembles generally agree on the upper level trough lingering over the Pacific Northwest into Monday before gradually shifting east into Monday night. This will most likely keep Monday cooler and showery. The grand ensemble continues to show some degree of offshore ridging becoming established Tuesday into midweek which would keep the Pacific Northwest under northerly flow aloft with some chance of showers possible - and slightly cooler than normal temperatures at least into midweek. && .AVIATION...A west to southwest zonal flow pattern will continue over western WA tonight into Friday with the strongest winds offshore (in a jet core). VFR conditions will continue this evening into Friday as high cirrus/stratus builds in over most terminals tonight. This will recede back to along the coast Friday morning (may be accompanied by some low MVFR stratus just offshore the Pacific Coastline) but otherwise more high clouds will build in the afternoon. Surface winds continue out of the north this evening at 8 to 12 knots, and will decrease below 5 kt tonight through Friday morning, picking back up out of the northwest at 5 to 10 kt. KSEA...VFR will continue with high clouds at times through Friday. North winds 8 to 12 knots this afternoon will ease after 06z to under 5 kt overnight through Friday night, and pick up out of the northwest 5 to 10 kt late Friday morning. Mazurkiewicz/HPR && .MARINE...Surface high pressure over the coastal waters will lead to generally benign marine conditions through Friday. A series of weak systems will cross over the waters over the weekend and into early next week, resulting in periodic increases in onshore flow over the area waters. Possible headlines over the weekend could include pushes down the Strait of Juan De Fuca, but not confident at this time. Coastal seas 4 to 6 feet into the weekend and into the early half of next week. Mazurkiewicz && .HYDROLOGY...The daily hydrology discussion has ended until the start of the next rainy season; it will only be updated if needed. && .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...None. && $$