417
FXUS66 KSEW 072349
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
349 PM PST Fri Feb 7 2025

.SYNOPSIS...A shortwave trough will bring the next chance for
showers and accumulating snowfall tonight through Saturday. Cool
temperatures and showery conditions will persist into Monday.
Drier and even colder temperatures are expected Tuesday and
Wednesday before another system moves into the region by the end
of next week.

&&

.SHORT TERM /TONIGHT THROUGH MONDAY/...Dry conditions will prevail
for much of the day as weak ridging moves over the Pacific
Northwest ahead of the next weather system. Clouds will continue
to increase through the afternoon as a shortwave trough slowly
moves towards the coast. Highs will peak a degree or two warmer
than yesterday, in the upper 30s to low 40s across the lowlands.

A shortwave feature will ripple across the region tonight,
generating another chance for accumulating snow overnight across
western Washington. With warmer temperatures in place closer to
the freezing mark, ensembles favor lighter accumulations that may
have a tough time sticking to hard surfaces, though temperatures
will have a large influence over precipitation type and
accumulation amounts. Also, due to the showery nature of
precipitation, snow totals once again may be highly variable
depending on where snow banding sets up. Along the coast, warmer
temperatures in place will likely cause precipitation to initially
fall as rain or a rain snow mix before changing over to snow as
temperatures fall overnight. Lowlands east of the Puget Sound
carry a moderate (40% to 50%) chance of half an inch of snow
accumulation and a low (25% to 35% chance) of up to an inch of
snow through Saturday morning, which may be impacted by
downsloping easterly winds that allow for slightly warmer
temperatures and a rain snow mix at times. Areas over the Kitsap
Peninsula and Hood Canal may see higher snow totals through
Saturday morning closer to 1 to 2 inches, enhanced by upslope
along the eastern slopes of the Olympics. The Olympics and
Cascades will also see a few inches of accumulating snowfall
through Saturday morning, including Stevens and Snoqualmie Passes.

Shower activity will continue into Saturday afternoon as an upper
level longwave trough axis swings across the Pacific Northwest.
Warmer temperatures in place will allow for a rain snow mix at
times, with additional accumulations over the lowlands favored to
melt off quickly. A drier air mass will fill in behind by Saturday
evening, with any additional snow accumulations confined to the
mountains through Sunday. The lowlands may see brief flurries or
drizzle with no impacts expected.

Temperatures will drop once again by the end of the weekend as
northwest flow settles in aloft, with overnight lows falling
below freezing Sunday night into Monday morning. While Monday
looks to stay mostly dry, a positively tilted trough will funnel
in colder air into the region with highs roughly 15 degrees below
normal and low temperatures 20 degrees below normal in some
places. Many sites across western Washington are flirting with
daily low temperature records Monday night into Tuesday morning,
including SeaTac (21 degrees set in 1948), Olympia (18 degrees set
in 1948), and Quillayute (22 degrees set in 1978).

.LONG TERM /TUESDAY THROUGH FRIDAY/...Cold conditions will persist
into mid-week, but some uncertainty remains over just how cold
things will get across western Washington. Dry conditions and
clear skies paired with northerly flow aloft will allow for
continued cold conditions on Tuesday with another round of very
cold temperatures in the teens and low 20s Tuesday night into
Wednesday morning. Forecast uncertainty increases mid to late
week as the spread in temperatures increases, with potential for
more widespread precipitation and warmer temperatures towards the
end of next week.

Lindeman

&&

.AVIATION...Currently a mix of VFR/MVFR ceilings across the
terminals as cloud cover continues to push into Western Washington
ahead of an incoming weather system. Ceilings are expected to lower
to MVFR tonight into Saturday morning, with the exception of KPWT
and KOLM, where guidance is hinting at conditions deteriorating to
IFR. Chances of precipitation will increase tonight and remain in
the forecast through Saturday morning. Scattered showers are
expected to start off as rain tonight and transition into a
rain/snow mix by early Saturday morning. Southerly winds at 2 to 5
kt becoming northerly/northeasterly at 2 to 6 kt by Saturday night.

KSEA...Ceilings bouncing between VFR/MVFR as cloud cover continues
to move across the terminal. Conditions are expected to lower to
MVFR after 12Z. Scattered showers are expected to move in later
tonight (beginning around 6Z-7Z) into Saturday morning.
Precipitation will start off as rain and then transition into a
rain/snow mix after 10Z Saturday. Southerly winds at 2 to 5 kt will
eventually switch more northerly (4 to 6 kt) late Saturday night.

MGF

&&

.MARINE...A surface trough will begin to move inland this afternoon
bring southerly flow to the coastal waters. Another system will move
over the waters on Saturday with winds shifting to the north through
the weekend. Winds are expected to increase starting Saturday
afternoon and subside by Sunday night over the far outer waters, but
are expected to remain below small craft advisory criteria. The next
weather system will move over the coastal waters on Wednesday night.

Combined seas will remain below 10 ft through the weekend and early
next week, with seas generally 4 to 7 ft.

MGF

&&

.HYDROLOGY...No river flooding expected over the next 7 days.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...None.
&&

$$