Napavine, Washington Weather Forecast Discussion

391
FXUS66 KSEW 192203
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
303 PM PDT Fri Sep 19 2025
.SYNOPSIS...Dry and mild conditions will continue today ahead of
widespread rain, breezy winds, and cooler temperatures over the
weekend. Conditions will dry out early next week as high pressure
builds into the region.
&&
.SHORT TERM /TONIGHT THROUGH MONDAY/...There`s weak upper level
ridging over the region today for generally mild weather
conditions. Smoke from the Bear Gulch Fire (and Tunnel Creek
Fire) has drifted south through southern Mason County with pockets
of degraded air quality. Smoke will drift east tonight with
improving conditions this weekend as a frontal system sweeps
through.
Saturday will start dry with rain increasing Saturday evening as
the next frontal system moves in. All areas will see rain with
this system with good wetting rains over the mountains. On Sunday,
we`re in post-frontal onshore flow with additional showers
expected and a convergence zone over the central sound. Total
rainfall through the weekend is around 0.50-1.00" for the coast
and mountains and 0.25-0.50" for the interior lowlands.
We`ll start to dry out again on Monday as high pressure returns.
Temperatures will track close to average with highs in the 60s to
lower 70s and overnight lows in the mid 40s and 50s. 33
.LONG TERM /TUESDAY THROUGH FRIDAY/...High pressure remains over
the region on Tuesday for dry and slightly warmer conditions. The
flow will turn weakly offshore and we will see temperatures in
the 70s to lower 80s again. The upper ridge flattens over the Pac
NW toward midweek, while systems split/weaken as they approach
WA. Ensembles are mainly dry through Friday. The flow remains
onshore with temperatures near to slightly cooler than average
through the end of the week. 33
&&
.AVIATION...VFR across the terminals this afternoon and will prevail
for the rest of today. Guidance hints at a push of low stratus
Saturday morning. There is some uncertainty in the eastward extent
of the stratus, but the highest confidence of seeing IFR/LIFR
ceilings are along the coast. It is possible the stratus may reach
terminals such as PWT, OLM, and CLM, with current probabilities at
20%-45% of seeing IFR/LIFR ceilings. Improvement into VFR for the
interior terminals is expected after 16z-20z if the stratus does
reach, while conditions at the coast will likely only improve to
MVFR in the afternoon. Breezy conditions along BLI Saturday
afternoon with gusts up to 20 kt possible.
KSEA...VFR will persist through the TAF period. NW winds this
afternoon through the evening at 5-7 kt. Winds will shift more
northerly after 01z-02z. S/SW winds return Saturday morning after
10z-12z, increasing to 7-10 kt in the afternoon/evening.
29
&&
.MARINE...High pressure will remain over the waters today and
weaken tonight as a frontal system approaches the coastal waters.
The frontal system is expected to move over the waters Saturday
evening into Sunday morning and will bring increased winds through
area waters. Southwesterly winds will increase over the coastal
waters as the front pushes through, with gusts up to 25 kt possible.
A Small Craft Advisory has been issued for the coastal waters
starting Saturday afternoon. Winds may approach small craft
thresholds for the central Strait and inland waters as the front
pushes through. Currently the highest chances are along the northern
interior waters (particularly Bellingham Bay), with probabilities
sitting at 45%-65% of exceeding 21 kt. In addition, may see gusts up
to 30 kt along Bellingham Bay (40%-55% chance). Guidance has been
consistent in showing a strong signal for a strong push of
westerlies through the Strait of Juan de Fuca behind the front on
Sunday morning, with the potential for gusts to approach low end
gales (40%-50% chance). High pressure rebuilds on Monday but will
on Tuesday as another front is expected to move over the waters.
Combined seas of 4-6 ft through early Saturday. Seas will build
Saturday evening to 6-9 ft through Monday.
29
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory from 2 PM Saturday to 2 AM PDT 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.
&&
$$

NWS SEW Office Area Forecast Discussion