Brier Weather Station
Latitude N 47° 46' 49" Longitude W 122° 16' 48" Elevation 341 ft
096
FXUS66 KSEW 151147
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
346 AM PST Mon Dec 15 2025
.SYNOPSIS...A period of very active weather will dominate the week
ahead as a series of strong frontal systems produce cascading
impacts across Western Washington. In addition to ongoing river
flood concerns, periods of windy conditions are expected today and
again Tuesday night into Wednesday. Snow levels will tumble to the
passes Tuesday night and Wednesday with heavy snowfall expected in
the mountains. Cool, unsettled conditions will remain in place
through the remainder of the week with substantial additional
snowfall in the mountains.
&&
.SHORT TERM /TODAY THROUGH WEDNESDAY/...
Rain is increasing again this morning as a warm front lifts
northward across Western Washington. Moderate to locally heavy rain
and gusty winds will persist through the day before a trailing cold
front sweeps through by early this evening with rain turning to
showers and isolated thunderstorms. Though QPF is lighter with this
system than those of last week, the additional rainfall and high
snow levels will push a number of rivers back into flood flow and
continue the threat of landslides. After a brief lull between
systems Monday night into early Tuesday, a secondary stronger system
arrives later Tuesday. And this one has some worrisome wind
potential with it. When combined with saturated soils already in
place, the threat of fallen trees increases. Models show a sharp
surface mesolow forming to the lee of the Olympics by 09Z Wednesday.
This creates a very strong pressure gradient Seattle southward.
Isallobaric analysis shows impressively strong pressure rises behind
it...as much as 7 or 8 millibars in just three hours early Wednesday
morning. So, it`s not just wind speeds alone, but the rapid manner
in which they could arrive. As such, we have put up a high wind
watch for all of the lowlands Tuesday evening into Wednesday morning
with gusts of 50 to 55 mph possible for the interior lowlands and 60
to 65 along the coast. Snow levels will tumble to the passes late
Tuesday night with significant snowfall expected. Totals could
approach a foot at Snoqualmie Pass by midday Wednesday, 1 to 2 feet
at Stevens, and perhaps 2 to 3 feet at Mount Baker.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
Model consensus keeps the pattern active and unsettled throughout
the extended portion of the forecast. However, the air mass will
remain considerably cooler with snow levels at or below passes into
the weekend. This will allow rivers to recede while snow piles up in
the mountains...a long awaited return to some semblance of normalcy
for December. 27
&&
.AVIATION...A frontal system will move through the area this
afternoon. A stronger system will arrive Tuesday night into
Wednesday with strong winds both aloft and at the surface.
Southwesterly flow aloft through Tuesday.
VFR ceilings with areas of MVFR ceilings and visibilities early this
morning. MVFR conditions becoming widespread by 16z with local IFR
ceilings coast and Kitsap peninsula. Conditions improving to VFR
late afternoon/early evening with mostly VFR conditions into Tuesday
morning.
KSEA...VFR conditions becoming MVFR by 15z. Conditions improving
late afternoon with VFR ceilings tonight. South winds 5 to 10 knots
increasing to 12 to 18 knots with gusts 25 to 30 knots 16z-18z.
Winds easing to 10 to 15 knots after 06z. Felton
&&
.MARINE...A front will move through the waters today. A stronger
system will arrive Tuesday night into Wednesday morning with another
system Thursday.
Gale force winds today over the waters. Winds easing late this
afternoon into tonight. Small craft advisory winds over the coastal
waters tonight into Tuesday afternoon. Another round of gales for
all the waters later Tuesday into Wednesday morning.
Winds easing Wednesday afternoon.
Seas 14 to 18 feet today subsiding to 10 to 13 feet tonight.
Seas continuing to subside slightly Tuesday before building again to
14 to 18 feet later Tuesday night into Wednesday. Seas subsiding to
9 to 12 feet Wednesday night. Felton
&&
.HYDROLOGY...Most rivers will continue to recede this morning.
Atmospheric river arriving later morning with rivers rising again by
afternoon. Even with the rises most of the rivers staying below
flood stage today. Rivers over flood stage will be the ones that
will have not dropped below much below flood stage over the weekend
like the Skagit, Cedar, White and Cowlitz below Mayfield Dam.
Rain easing tonight into Tuesday before another front reaches the
area later Tuesday into Wednesday increasing precipitation rates.
This second round of precipitation will drive some rivers above
flood stage with major flooding possible along the Skagit and
moderate flooding for the river flowing out of the Central Cascades
like the Skykomish, Snoqualmie and Snohomish. The Skokomish could
also reach moderate flood stage.
Cooler air moving into the area Tuesday night adds some uncertainty
to the river levels. Current forecasts have snow levels dropping to
2000 to 2500 feet by Wednesday morning. The front Tuesday night into
Wednesday has more moisture than the todays system but the cooler
air will keep some of the moisture in the mountains in the form of
snow. This combination makes for tricky river forecasting.
A flood watch is in effect through Thursday afternoon across the
lowlands.
With a couple more rounds of precipitation the landslide threat will
remain very elevated through Thursday. Felton
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Wind Advisory until 10 PM PST this evening for City of Seattle-
Downtown Everett / Marysville Area-Eastern Kitsap County-
Eastside-Foothills of the Western and Southern Olympic
Peninsula-Grays Harbor County Coast-Island County-Lower
Chehalis River Valley-Lowlands of Lewis and Southern
Thurston Counties-Lowlands of Pierce and Southern King
Counties-Lowlands of Western Skagit and Northwestern
Snohomish Counties-Lowlands of Western Whatcom County-
Middle Chehalis River Valley-Northern Hood Canal-Northern
Washington Coast-Olympia and Southern Puget Sound-Port
Townsend Area-San Juan County-Shoreline / Lynnwood /
South Everett Area-Southern Hood Canal-Western Strait of
Juan de Fuca-Willapa and Black Hills.
High Wind Watch from Tuesday evening through Wednesday morning
for City of Seattle-Downtown Everett / Marysville Area-
Eastern Kitsap County-Eastern Strait of Juan de Fuca-
Eastside-Foothills and Valleys of Central King County-
Foothills and Valleys of Pierce and Southern King
Counties-Foothills and Valleys of Snohomish and Northern
King Counties-Foothills and Valleys of Thurston and Lewis
Counties-Foothills and Valleys of the North Cascades-
Foothills of the Western and Southern Olympic Peninsula-
Grays Harbor County Coast-Island County-Lake Crescent
Area Including US 101-Lower Chehalis River Valley-
Lowlands of Lewis and Southern Thurston Counties-Lowlands
of Pierce and Southern King Counties-Lowlands of Western
Skagit and Northwestern Snohomish Counties-Lowlands of
Western Whatcom County-Middle Chehalis River Valley-
Northern Hood Canal-Northern Washington Coast-Olympia and
Southern Puget Sound-Port Townsend Area-San Juan County-
Shoreline / Lynnwood / South Everett Area-Southern Hood
Canal-Western Strait of Juan de Fuca-Willapa and Black
Hills.
Flood Watch from 10 AM PST this morning through Thursday
afternoon for Cascades of Pierce and Lewis Counties-
Cascades of Snohomish and Northern King Counties-Cascades
of Southern King County-Cascades of Whatcom and Skagit
Counties-City of Seattle-Downtown Everett / Marysville
Area-Eastern Kitsap County-Eastern Strait of Juan de Fuca-
Eastside-Foothills and Valleys of Central King County-
Foothills and Valleys of Pierce and Southern King
Counties-Foothills and Valleys of Snohomish and Northern
King Counties-Foothills and Valleys of Thurston and Lewis
Counties-Foothills and Valleys of the North Cascades-
Foothills of the Western and Southern Olympic Peninsula-
Grays Harbor County Coast-Lake Crescent Area Including US
101-Lower Chehalis River Valley-Lowlands of Lewis and
Southern Thurston Counties-Lowlands of Pierce and
Southern King Counties-Lowlands of Western Skagit and
Northwestern Snohomish Counties-Lowlands of Western
Whatcom County-Middle Chehalis River Valley-Northern Hood
Canal-Northern Washington Coast-Olympia and Southern
Puget Sound-Olympics-Port Townsend Area-Shoreline /
Lynnwood / South Everett Area-Southern Hood Canal-Western
Strait of Juan de Fuca-Willapa and Black Hills.
Winter Storm Watch from Tuesday evening through Wednesday
evening for Cascades of Pierce and Lewis Counties-
Cascades of Snohomish and Northern King Counties-Cascades
of Southern King County-Cascades of Whatcom and Skagit
Counties-Olympics.
PZ...Small Craft Advisory until 10 AM PST Tuesday for Grays Harbor
Bar.
Gale Warning until 6 PM PST this evening for Admiralty Inlet-
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-
Northern Inland Waters Including The San Juan Islands-
Puget Sound and Hood Canal-West Entrance U.S. Waters
Strait Of Juan De Fuca.
Small Craft Advisory from 6 PM this evening to noon PST
Tuesday 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-
West Entrance U.S. Waters Strait Of Juan De Fuca.
Gale Watch from Tuesday afternoon through Wednesday morning
for 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-West Entrance U.S.
Waters Strait Of Juan De Fuca.
Gale Warning from 1 PM this afternoon to 1 AM PST Tuesday for
Central U.S. Waters Strait Of Juan De Fuca.
Gale Warning until 1 AM PST Tuesday for East Entrance U.S.
Waters Strait Of Juan De Fuca.
Gale Watch from Tuesday evening through Wednesday morning for
Admiralty Inlet-East Entrance U.S. Waters Strait Of Juan
De Fuca-Northern Inland Waters Including The San Juan
Islands-Puget Sound and Hood Canal.
&&
$$
NWS SEW Office Area Forecast Discussion