372 FXUS66 KSEW 170438 CCA AFDSEW Area Forecast Discussion National Weather Service Seattle WA 756 PM PDT Wed Apr 16 2025 .SYNOPSIS...Upper level ridge building into the British Columbia coast tonight will slide south over Western Washington by Friday. The ridge will shift east Friday night with an upper level trough over the area for the weekend. The trough will move east Monday with a weaker trough for Tuesday. Another upper level ridge beginning to build Wednesday. && .SHORT TERM /TONIGHT THROUGH SUNDAY/...Updates from the Space Weather Prediction Center shows the magnetic field has peaked and will gradually weaken tonight, decreasing in favorability for a northern lights display for western Washington. Otherwise, the latest forecast remains on track with no updates this evening. Satellite imagery shows clear skies over western Washington this evening with breezy northerly winds tapering down as a trough moves to the east of the Cascades. Upper level ridging will continue to build into the British Columbia coast tonight with dry northerly flow aloft over the area, remaining over British Columbia Thursday. Northerly winds will pick up Thursday afternoon but will not be as strong as today. This combined with a little warmer temperatures aloft will push highs into the lower to mid 60s. Upper level ridge axis sagging south Thursday night. The ridge axis will be right over Western Washington Friday making it the warmest day in the next seven days. Many locations in the interior from Seattle southward will get into the lower 70s. This will be the second 70 degree plus day of the month for Seattle and the third one this year. Mid to upper 60s for the remainder of the interior. Northwesterly winds off the cool ocean will keep temperatures along the coast in the lower 60s. Lows Friday morning in the mid 30s to lower 40s. Upper level ridge shifting east Friday night with an upper level trough moving into the area Saturday. Trough axis moving through Western Washington Saturday morning bringing showers to the area. With the increasing cloud cover Friday night lows will remain in the 40s. Highs Saturday much cooler with the trough overhead, in the mid to upper 50s. .LONG TERM /MONDAY THROUGH THURSDAY/...Extended models in good agreement with an upper level trough remaining over Western Washington keeping showers and cool daytime highs in the forecast Sunday. Trough moving east Monday with showers coming to an end. A weaker trough arriving Tuesday. Not much moisture with this feature. Low level onshore flow will keep high temperatures near 60. Upper level ridge building offshore Wednesday with temperatures aloft warming a little. Northwesterly winds will again limit high temperatures along the coast to the upper 50s. For the interior upper 50s to mid 60s. With the clearing there could be some frost problems Tuesday night/Wednesday morning. Felton && .AVIATION...An upper level ridge will build into the British Columbia coast overnight into Thursday producing northerly flow aloft over Western Washington. The air mass is dry and stable and the low level flow is northerly. Gusty northerly surface winds over the interior of Western Washington this evening will ease as surface high pressure over British Columbia expands southward. VFR will prevail. KSEA...Clear skies. Surface winds northerly 10 to 20 knots will ease this evening and turn northeasterly 6 to 10 knots overnight. 27 && .MARINE...Surface ridging will remain over the waters into Friday. A weak front and associated trough will slip southward along the British Columbia coast and into the area Friday night into Saturday. This will initiate an increase in onshore flow with likely headlines and possible gales in the central/east strait. A secondary system will produce a similar result later Sunday into early Monday. High pressure will then rebuild across the waters early next week. Hazardous coastal seas will subside below 10 feet Thursday and Friday before building back above 10 feet early in the weekend. 27 && .HYDROLOGY...No river flooding is expected over the next 7 days. && .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...Small Craft Advisory until 11 PM PDT this evening 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-Grays Harbor Bar. Small Craft Advisory until 10 PM PDT this evening for Puget Sound and Hood Canal. && $$