West Entrance U.S. Waters Strait of Juan de Fuca Marine Forecast
|Today...N Wind To 10 Kt Becoming W 5 To 15 Kt In The Afternoon. Wind Waves 1 To 3 Ft. Sw Swell 12 Ft At 12 Seconds Becoming W 8 Ft At 11 Seconds In The Afternoon. Showers Likely In The Morning Then A Chance Of Showers In The Afternoon.|
|Tonight...W Wind 5 To 15 Kt Becoming Sw To 10 Kt After Midnight. Wind Waves 2 To 4 Ft Subsiding To 1 To 2 Ft After Midnight. W Swell 6 Ft At 10 Seconds. Showers Likely In The Evening Then Showers After Midnight.|
|Thu...Sw Wind To 10 Kt Becoming W 5 To 15 Kt In The Afternoon. Wind Waves 1 To 2 Ft Building To 2 To 4 Ft In The Afternoon. W Swell 6 Ft At 10 Seconds. Showers Likely In The Morning Then Showers In The Afternoon.|
|Thu Night...W Wind 5 To 15 Kt Becoming To 10 Kt After Midnight. Wind Waves 2 To 4 Ft Subsiding To 1 To 2 Ft After Midnight. W Swell 5 Ft At 9 Seconds.|
|Fri...Ne Wind To 10 Kt. Wind Waves 1 To 2 Ft. W Swell 4 Ft At 9 Seconds.|
|Fri Night...Nw Wind To 10 Kt. Wind Waves 1 To 2 Ft. W Swell 4 Ft At 9 Seconds.|
|Sat...E Wind To 10 Kt Becoming Nw. Wind Waves 1 To 2 Ft. W Swell 4 Ft.|
|Sun...Light Wind Becoming Nw To 10 Kt. Wind Waves 1 To 2 Ft. Nw Swell 3 Ft.|
| Area Forecast Discussion|
National Weather Service Seattle WA
1017am PDT Wednesday September 27 2023
A dissipating surface low is currently over western Washington. As it continues to weaken and fill, showers are to remain throughout the day. Hi-res reflectivity guidance is indicating the development of a Puget Sound Convergence Zone over King County later this afternoon-evening. With meager instability in place, can't rule out a rumble of thunder or two. Highs are forecasted to top out into the lower 60s. The previous discussion is below along with an updated marine/aviation section.
An upper level trough will spread showers, isolated thunderstorms, and areas of gusty wind across Western Washington as it moves onshore and weakens today. Another upper trough will dig southward along the British Columbia coast on Thursday for continued cool and unsettled weather. A transition toward drier conditions will occur on Friday as the trough gradually shifts eastward. Upper level ridging will provide generally dry and cool conditions over the weekend. The ridge weakens early next week allowing a chance of rain to return to the forecast.
Short Term - Today through Friday
Tightly wrapped surface low around 100 nautical miles to the west of Astoria at 08Z is moving onshore early this morning in the vicinity of Grays Harbor. We're expecting this low to gradually fill and continue to weaken as it lifts northeastward across the area today. The end result will be a showery day across Western Washington with some gusty winds this morning...particularly across Grays Harbor and Lewis counties. We'll see shower activity begin to wind down across the lowlands by early evening...with the exception of a brief convergence zone that is likely to form over Snohomish/King counties. After a brief lull in shower activity overnight, precipitation coverage will increase Thursday morning as another upper trough digs southward over southern British Columbia. This system won't be nearly as wet as the previous couple, but it will keep showers going across much of the region and hold temperatures down below normal. A modest increase in onshore flow with the arrival of the trough will likely generate another convergence zone Thursday afternoon/early evening.
A transition toward drier conditions will take place on Friday as the trough axis shifts east of the Cascades. Apart from a few lingering showers in the Cascades, the remainder of the area will likely be dry with some sunshine breaking out in places by afternoon. After a cooler morning, high temperatures Friday afternoon will remain below normal...with most lowland locations struggling to get above 60 degrees.
Long Term - Saturday Through Tuesday
Upper ridging will start to nose into Western Washington on Saturday. Recent rains and longer nigheights will be a good recipe for some patchy fog Saturday morning and again on Sunday. With the building ridge and some sun, high temperatures will respond with a modest warming trend. Western Washington remains on the periphery the offshore ridge into Sunday for another dry day and temperatures edging closer to climatological norms. Early next week, there are indications that the ridge will flatten enough to allow a return of some rain chances Monday and beyond. However, a low amplitude and/or zonal flow pattern on days 6/7 in early October here generally results in a low confidence forecast. 27
A strong albeit small surface low is currently moving across the region, centered over the south Sound. Winds over the coastal regions have begun to ease from the gale force winds this morning, so have let the Gale Warnings expire, which will be replaced by a Small Craft Advisory through the rest of the day. Winds have also backed off in the Strait of Juan de Fuca and the northern interior waters, thus allowing the Small Craft Advisory to expire. Winds should remain 10-20 kt for these areas today.
Seas are currently 10-14 ft near the coast and 13-16 ft in the outer waters around 13 seconds. Seas will begin to drop to around 10-12 ft into this afternoon. Seas gradually lower to 6 to 8 ft Thursday through this weekend.
Small Craft Advisory winds are possible Thursday afternoon as high pressure begins building over the offshore waters and the pressure gradients turns positive once again. A weak cold front will sag southward over the area waters Friday with high pressure once again building over the eastern Pacific into the weekend with the potential for advisory-level northerly winds between the offshore high and inland low.
Rainfall amounts through early Thursday of 0.25-0.75" across the lowlands and 1-2" in the mountains won't be a concern for river flooding thanks to the dry antecedent conditions from earlier in the month. Attention will need to be paid to burn scars today with potentially heavy convective rainfall rates that will be in the vicinity. Drier conditions return for the upcoming weekend. No other heavy rainfall events are presently in the forecast picture into early next week.
NOAA Seattle WA Office: Watches - Warnings - Advisories
WA...None. PZ...Small Craft Advisory until noon PDT today for
Grays Harbor Bar
Small Craft Advisory until 11am PDT this morning for
West Entrance USA Waters Strait Of Juan De Fuca.
Small Craft Advisory until 6pm 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.