San Juan Islands and Northern Inland Waters Marine Forecast
|Tonight...N Wind To 10 Kt Becoming Se 5 To 15 Kt After Midnight. Wind Waves 2 Ft Or Less.|
|Thu...S Wind 10 To 20 Kt Rising To 15 To 25 Kt In The Afternoon. Wind Waves 2 To 4 Ft. A Chance Of Rain In The Afternoon.|
|Thu Night...Sw Wind 20 To 30 Kt Easing To 15 To 25 Kt After Midnight. Wind Waves 3 To 5 Ft. Showers In The Evening Then Showers Likely After Midnight.|
|Fri...Sw Wind 5 To 15 Kt Becoming W 15 To 25 Kt In The Afternoon. Wind Waves 2 Ft Or Less Building To 2 To 4 Ft In The Afternoon.|
|Fri Night...W Wind 15 To 25 Kt. Wind Waves 2 To 4 Ft.|
|Sat...W Wind 10 To 20 Kt. Wind Waves 1 To 3 Ft.|
|Sat Night...Sw Wind 10 To 20 Kt Becoming W 5 To 15 Kt After Midnight. Wind Waves 1 To 3 Ft.|
|Sun...W Wind 10 To 20 Kt Becoming Sw 15 To 25 Kt. Wind Waves 2 To 4 Ft.|
|Mon...W Wind To 10 Kt Becoming Sw. Wind Waves 1 Ft Or Less.|
| 244 PM PDT Wed May 5 2021 |
Northern and Central Washington Coastal and Inland Waters - PZZ100
Offshore flow through late tonight before turning onshore with the approach of a frontal system Thursday. Advisory level conditions expected at times across some waters Thursday through the weekend.
| Area Forecast Discussion|
National Weather Service Seattle WA
259pm PDT Wednesday May 5 2021
Dry conditions will continue through tonight, before a return to wet and unsettled conditions resume Thursday as a frontal system will brings rain, breezy winds, and cooler temperatures to western Washington. Showers will persist Friday and into the weekend as an upper level trough traverses the Inland Northwest and a weak system moves into the area. Drying trend commences Sunday into early next week as upper level ridging strengthens across the region.
Short Term - Tonight Through Saturday
Satellite shows a broken layer of high clouds moving over western Washington this afternoon ahead of the next system offshore. Meanwhile, latest observations show temperatures as of 2PM currently trending in the low to mid 60s across the region. Given ample cloud cover, have trended the temperature forecast down a couple of degrees this afternoon and have highs topping out in mid to upper 60s for areas in the vicinity of the Sound. A few spots could see 70 with offshore flow, but this will likely be near the foothills of the Cascades. Overall, expect the remainder of the evening to remain dry today, with increasing cloud cover ahead of the system offshore.
A frontal system will approach the region and move inland on Thursday, bringing a round of rain and breezy winds to western Washington. Rainfall amounts look to be a couple hundredths to a few tenths of an inch for the lowlands at this time. Southerly winds will become breezy late Thursday morning and look to peak across the region by late afternoon into early evening. Breeziest areas look to remain along the coast and the north interior along the frontal passage and along the Strait of Juan de Fuca with a surge of post- frontal onshore flow. Highs are still expected to be above normal and in the 60s on Thursday.
Rain will become more showery on Friday as an upper level trough moves inland and becomes slightly negatively tilted. Cooler air aloft will result in steepening lapse rates, increasing instability across the area in the post-frontal environment, so have kept a slight chance of thunder for areas across the interior late Friday morning into Friday afternoon. Guidance is still on track indicating that Friday will be the coolest day of the week-with afternoon temperatures only topping out in the low to upper 50s.
The upper level trough will continue to move east-southeastward into the Intermountain West on Saturday, while upper level ridging across the eastern Pacific starts to build back into the Pacific Northwest. Latest guidance still hinting at showers persisting over the weekend as a weak system rides the periphery of the ridge and moves into the area under northwesterly flow aloft. Rain amounts look to remain rather light at this time, with temperatures remaining cool- primarily in the 50s.
Long Term - Sunday Through Wednesday
Latest guidance still hinting at light showers persisting into Sunday, however expect an overall drying trend to commence late in the day as upper level ridging across the eastern Pacific starts to strengthen and build across the area. Ensemble guidance then shows a general drier trend persisting through the first part of next week. Highs will start to creep back up above normal early next week-back in the mid to upper 60s. 14
Offshore winds today as high pressure builds over area waters. Easterly winds in the Strait of Juan de Fuca will range from 10 to 20 kts this afternoon. Expect flow to swing back to onshore flow late tonight into Thursday morning and will increase to advisory levels for at least the coastal waters and the preferred portions of the Strait Thursday morning. Have stuck with this thinking even though latest model runs coming in a little higher on wind speeds. This will be something for next shift to evaluate, especially for the Western Strait and Puget Sound as they remain borderline headline criteria. Remaining waters, however, feel pretty confident with SCA (Small Craft Advisory) headline and that will go out with afternoon forecast package. Winds will remain elevated through Friday before gradually decreasing. Strong nocturnal westerly pushes expected in the Strait through the weekend. Another push of advisory level winds will be possible offshore on Sunday with the passage of another system.
Offshore seas will increase on Thursday, with westerly swells building to 6 to 8 feet before gradually decreasing Friday through the weekend. At least 2 to 4 foot wind waves will be possible across portions of the inland waters Thursday and Friday. Another increase in swells possible on Sunday with the passage of the next system. Swells will remain below 10 feet.
.SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...Small Craft Advisory from 5am Thursday to 5am PDT Friday for Admiralty Inlet-Central U.S. Waters Strait Of Juan De Fuca- 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-East Entrance U.S. Waters Strait Of Juan De Fuca-Northern Inland Waters Including The San Juan Islands.