Marine Weather Net

Cape Flattery to James Island WA out 10 to 60 NM Marine Forecast


TONIGHT

NE
WINDS
10 - 20
KNOTS

TUE

SE
WINDS
15 - 25
KNOTS

TUE NIGHT

SW
WINDS
20 - 30
KNOTS

WED

W
WINDS
20 - 30
KNOTS

The Marine Weather Forecast In Detail:
PZZ170 Forecast Issued: 854 PM PST Mon Nov 28 2022

GALE WARNING IN EFFECT FROM 6 AM PST TUESDAY THROUGH TUESDAY EVENING
Tonight...Ne Wind 10 To 20 Kt. Wind Waves 2 To 4 Ft. W Swell 10 Ft At 13 Seconds.
Tue...Se Wind 15 To 25 Kt Becoming S 25 To 35 Kt In The Afternoon. Combined Seas 8 To 9 Ft With A Dominant Period Of 13 Seconds. A Chance Of Showers In The Morning Then Showers In The Afternoon.
Tue Night...S Wind 30 To 40 Kt Becoming Sw 20 To 30 Kt After Midnight. Combined Seas 8 To 10 Ft With A Dominant Period Of 12 Seconds Building To 10 To 13 Ft With A Dominant Period Of 12 Seconds After Midnight. Rain.
Wed...W Wind 20 To 30 Kt Rising To 25 To 35 Kt In The Afternoon. Combined Seas 14 To 17 Ft With A Dominant Period Of 12 Seconds.
Wed Night...Sw Wind 15 To 25 Kt. Wind Waves 3 To 5 Ft. W Swell 15 Ft At 12 Seconds.
Thu...E Wind 20 To 30 Kt Easing To 15 To 25 Kt In The Afternoon. Wind Waves 4 To 6 Ft. W Swell 12 Ft At 13 Seconds.
Thu Night...Ne Wind To 10 Kt Becoming S After Midnight. Wind Waves 1 To 2 Ft. W Swell 8 Ft At 12 Seconds.
Fri...S Wind 15 To 25 Kt. Wind Waves 3 To 5 Ft. Nw Swell 5 Ft Building To W.
Sat...E Wind 5 To 15 Kt Becoming Ne. Wind Waves 1 To 3 Ft. W Swell 10 Ft Subsiding To 6 Ft.
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Area Forecast Discussion
National Weather Service Seattle WA
807pm PST Monday Nov 28 2022

Synopsis
A weather system will be moving through the area tomorrow. There is a lot of variability with this system and precipitation amount is going to be very dependent on location, elevation and timing. Additionally, strong southerly winds will be picking up during the afternoon. Conditions easing later Wednesday with showers remaining in through Thursday. Another system expected to impact the area this weekend.

Short Term - Tonight Through Thursday
Fraser River outflow winds and pressure gradients have been easing this evening and the Wind Advisory for western Whatcom and the San Juans was cancelled. It's in the 20s up north in places like Whatcom and Skagit but still in the lower to mid 30s Seattle on south. Dew points are low, though, in the teens and we are seeing some clearing so overnight lows are still expected to drop below freezing overnight. 33

Previous discussion...A frontal system will begin moving through the area tomorrow morning. Despite it being less than 24hrs before the start of the event there remains uncertainty to the forecast. With this type of set up, the forecast is still very variable and is going to change all the way up to the event. Make sure to check for the latest forecast and overall conditions before heading out.

Lowland Snow:

Not as much cold air has moved into the area as initially expected. The relatively warmer surface conditions will working against lowland snow. It is not just temperatures that are working against lowland snow, wind will also be a factor. Ahead of the front the easterly winds will work to dry out low levels. As the warm front moves through strong persistent southerlies will raise snow and freezing levels up. Making the potential for lowland snow decrease. That said, there is still the potential. With high precipitation rates dragging cold air aloft down to the surface there remains the potential for accumulating snow in the lowlands.

Snow on the east side of the Olympic Peninsula and South of the Olympic mountains could begin seeing snow during the period of easterly winds ahead of the frontal system. This area will likely transition over to rain as the warm front moves through. However, additional snow is possible during heavier periods of precipitation.

The big question mark in precipitation type is for the Seattle metro area. Between the easterlies and southerlies the chance of accumulating snow for the south end of the area is less likely. For the north end precipitation rates could be strong enough that areas do see some wet slushy accumulations. This is most likely on the higher hills of the area. The north side of the Seattle metro area will also have the potential for snow due to post frontal convergence early Wednesday morning.

The lowland snow accumulation for north of the Seattle metro is tricky. Snow levels are expected to only rise to 2000 feet briefly during the early morning hours Wednesday. With the more persistent cold air the chance of accumulation is more likely particularly when it comes to the post frontal showers Wednesday morning.

Mountain Snow:

The slight increase in snow levels during the southerlies are not expected to impact the snow amounts for the mountains. Heavy mountain snow is expected to begin late Tuesday morning for the Olympics and Tuesday afternoon for the Cascades. Snow accumulations of 1 to 2 feet are expected at the Cascades Passes, Hurricane Ridge and Paradise at Mount Rainier.

The cold front is expected to have moved out of the area by late Tuesday night. Leaving the post frontal showers in its wake. The precipitation type in these post frontal showers is going to be very dependent on the shower intensity and elevation. As showers continue into Thursday colder air will continue to filter in, increasing the probability of snow for all locations.

Wind:

In addition to precipitation, this frontal system is going to produce windy condition's throughout the area Tuesday afternoon as the cold front approaches. The strongest winds are expected to be over our area waters and the adjacent land during the overnight hours. Gusts up to 50 to 60 mph are expected for the San Juans, Admiralty Inlet, Island, and Western Whatcom and Skagit counties. While windy, the rest of the lowland interior winds will be lower with gusts closer to the 30 to 40 mph. Winds area wide will subside through the morning hours.

Long Term - Friday Through Monday
Cold air is expected to remain in place through the long term period with lows expected to remain in the 20s and highs in the upper 30s to low 40s for the lowlands. Additionally, we are expecting another frontal system to move through the area beginning Friday. With cold conditions and another frontal system moving through we are expecting another round of mountain snow and another chance of accumulating lowland snow.

Marine
Complicated forecast as models trending a little easier on the winds. This, combined with current observations, will allow for the cancellation of inherited Small Craft Advisories in Puget Sound, the Northern Inland Waters and the East Strait. Remaining headlines may need additional adjustment, but will allow full suite of 00Z data to come in before making any judgments. The next incoming system will move through Tuesday evening and Wednesday for increasing south-southeasterly winds across the area. Gales are likely for the coastal waters during this time period, as well as the northern inland waters and Puget Sound. Also, there is a chance for Storm Force winds/gusts across the eastern Strait of Juan de Fuca Tuesday night into Wednesday morning. Winds will taper a bit Wednesday afternoon for additional Small Craft Advisory winds. Offshore winds increase Wednesday night and into Thursday and remain elevated into the weekend.

Seas of 8 to 10 ft tonight into Tuesday morning. Seas will build Wednesday to 13 to 17 ft subsiding Thursday into Thursday night.

McMillian/18

Hydrology
There will be active weather this week with significant amounts of precipitation, but snow levels will be low, near sea level in the north to below 3000 feet in the south near the coast. Rivers will rise, especially the Skokomish, but there will not likely be enough storm runoff for river flooding due to the snowfall over much of the area.

NOAA Seattle WA Office: Watches - Warnings - Advisories
WA...Winter Storm Watch from Tuesday afternoon through Wednesday afternoon for Admiralty Inlet Area-Bremerton and Vicinity- East Puget Sound Lowlands-Eastern Strait of Juan de Fuca- Everett and Vicinity-Hood Canal Area-Lower Chehalis Valley Area-Olympics-West Slopes North Cascades and Passes-West Slopes North Central Cascades and Passes-West Slopes South Central Cascades and Passes-Western Skagit County-Western Strait of Juan De Fuca-Western Whatcom County.

Winter Weather Advisory from 1pm Tuesday to 10am PST Wednesday for Bellevue and Vicinity-Seattle and Vicinity.

PZ...Small Craft Advisory until 10am PST Wednesday for
West Entrance USA Waters Strait Of Juan De Fuca.

Storm Watch from Tuesday afternoon through late Tuesday night for
Admiralty Inlet
East Entrance U.S. Waters Strait Of Juan De Fuca-
Northern Inland Waters Including The San Juan Islands.

Gale Watch from Tuesday afternoon through late Tuesday night for
Puget Sound and Hood Canal

Small Craft Advisory until 7am PST Tuesday for
Coastal Waters From Cape Flattery To James Island Out 10 Nm.

Gale Warning from 7am to 10pm PST Tuesday for
Coastal Waters From Cape Flattery To James Island Out 10 Nm.

Gale Warning from 6am to 10pm PST Tuesday for
Coastal Waters From Cape Flattery To James Island 10 To 60 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.