Winter Weather in Washington, February 25 to 26, 2023

Area Forecast Discussion
National Weather Service Seattle WA
242 PM PST Sat Feb 25 2023

.SYNOPSIS...A front will bring a threat of lowland snow tonight
and Sunday morning with heavy snow in the mountains. It will
remain cool and showery Monday and Tuesday with an upper trough.
High pressure will bring brief drying on Wednesday then a wet
frontal system will move through the area on Thursday. It will
remain showery with low snow levels into next weekend as another
upper low moves overhead.

&&

.SHORT TERM /TONIGHT THROUGH TUESDAY/...Precipitation will spread
into Western Washington this evening as a front arrives. It will
be cold enough for lowland snow with dry air at the surface
allowing for some wet bulb cooling as the precipitation arrives.
At the same time, southerly winds will be increasing tonight and
the air mass will be slowly warming. The result is a messy and
complicated lowland snow forecast. The most likely scenario is
most of the area getting advisory amounts (up to 3") with locally
higher totals over the Hood Canal Area/Kitsap Peninsula, Western
Whatcom County, and higher terrain near the Cascades and Olympics.

It will remain showery on Sunday behind the front but
temperatures will climb into the lower 40s most areas and the
lowland accumulating snow threat should be over by late morning.
The mountains will get a good shot of snow tonight and Sunday
with 12-18" likely.

An upper trough will slowly shift through the area Monday and
Tuesday, keeping showers in the forecast. It will be marginally
cold enough for lowland snow accumulations each day during the
overnight and early morning hours. Widespread impactful
accumulations are not expected but minor accumulations are
certainly possible each day. The best chance for an additional
inch or two early Monday looks to be over the Southwest Interior
and Kitsap Peninsula as a short wave brings a more organized batch
of showers into the area from the south. It will remain
unseasonably cool with highs mostly in the lower to mid 40s and
lows in the lower 30s. 16

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...It will remain
unseasonably cool through the end of the week with a threat of
snow for the lowlands each day, mainly night and early morning
hours. Highs will be in the lower to mid 40s each day and lows
will be in the lower to mid 40s.

An upper ridge will bring a mostly dry day on Wednesday but the
respite will be brief. A frontal system will push through the
area on Thursday. Snow levels will be high enough during the day
that precipitation should be all rain for the lowlands. Snow
levels drop below 1000 feet again Thursday night behind the front
for yet another chance of spotty lowland snow.

Another upper low will will drop down from the north to just off
the coast Friday and Saturday. This will maintain the cool and
showery pattern with snow levels within a few hundred feet of sea
level each night and early morning. 16

&&

.AVIATION...Flow has turned westerly as an upper level ridge over
Western Washington continues to flatten. VFR conditions will
continue this afternoon into the early evening before
deteriorating tonight. An upper level trough will continue to dig
into our region with increasing mid to high level clouds
throughout the evening as a frontal system moves in.

As this frontal system slides in from the northwest this evening,
KBLI and KCLM will be the first to see snow and or a rain/snow
mix between 01-03z. Precipitation will spread inland into more
inland terminals generally around the 03-06z timeframe. Southerly
winds will also increase around 10 to 15 knots with gusts
generally around 20 to 25 knots. Elsewhere, generally snow showers
or a mix of rain/snow can be expected throughout most area
terminals. MVFR/IFR ceilings and visibilities can be expected
throughout most of the night and into Sunday morning, especially
within heavier snow showers.

KSEA...VFR conditions through the afternoon will start to
deteriorate later this evening around 03-05z onward. Ceilings will
begin to lower as precipitation spreads through the terminal. A
rain/snow mix looks to start around 03z as precipitation type
will generally be a mix of rain/snow and light snow showers.
Generally at the terminal, half a inch to an inch of wet snow is
possible. MVFR to IFR conditions can be expected especially under
heavier bands of precip. NE winds will shift to southerly and
gradually increase to 10 to 15 kts late tonight into Sunday
morning.

Maz

&&

.MARINE...A frontal system will enter our area waters this evening
with increasing southerly winds over all waters. A Small Craft
Advisory is already in effect for the coastal waters ahead of the
approaching system.

Have upgraded Gale Watches to Gale Warnings for the Northern
Inland Waters, Eastern Strait, and Admiralty Inlet area tonight
into Sunday afternoon. Southerly winds within the Puget Sound
will be breezy, around 20 to 30 kt, and will remain under gale
force.

As the frontal system exits on Sunday morning, post frontal
westerlies will surge into the Strait of Juan De Fuca, with gale
warnings extended to the Western and Central Strait.

Combined seas building to 5 to 7 feet tonight before building up
into the 11 to 13 range by early Sunday morning.

Maz

&&

.HYDROLOGY...River flooding is not expected for the next 7 days.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Winter Weather Advisory from 4 PM this afternoon to 10 AM PST
     Sunday for Central Coast-Eastern Strait of Juan de Fuca-
     North Coast-San Juan County-Western Skagit County-Western
     Strait of Juan De Fuca-Western Whatcom County.

     Winter Weather Advisory from 8 PM this evening to noon PST
     Sunday for Lower Chehalis Valley Area-Southwest Interior.

     Winter Weather Advisory from 6 PM this evening to 10 AM PST
     Sunday for Admiralty Inlet Area-Bellevue and Vicinity-
     Everett and Vicinity-Seattle and Vicinity-Tacoma Area.

     Winter Weather Advisory from 4 PM this afternoon to 4 AM PST
     Sunday for Bremerton and Vicinity-Hood Canal Area.

     Winter Weather Advisory from 4 PM this afternoon to 4 PM PST
     Sunday for Olympics.

     Winter Weather Advisory from 8 PM this evening to 10 AM PST
     Sunday for East Puget Sound Lowlands.

     Winter Storm Warning from 10 PM this evening to 10 PM PST Sunday
     for West Slopes North Cascades and Passes-West Slopes North
     Central Cascades and Passes.

     Winter Weather Advisory from 10 PM this evening to 10 PM PST
     Sunday for West Slopes South Central Cascades and Passes.

PZ...Small Craft Advisory from 4 AM Sunday to 4 AM PST Monday for
     Grays Harbor Bar.

     Gale Warning from 1 AM to 1 PM PST Sunday for Central U.S.
     Waters Strait Of Juan De Fuca-West Entrance U.S. Waters
     Strait Of Juan De Fuca.

     Gale Warning from 4 PM this afternoon to 1 PM PST Sunday for
     East Entrance U.S. Waters Strait Of Juan De Fuca.

     Gale Warning from 4 PM this afternoon to 10 AM PST Sunday for
     Admiralty Inlet-Northern Inland Waters Including The San
     Juan Islands.

     Small Craft Advisory from 4 PM this afternoon to 1 PM PST Sunday
     for Puget Sound and Hood Canal.

     Small Craft Advisory until 1 PM PST Sunday 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.

&&