Cohasset Beach, Washington Weather Forecast Discussion

168
FXUS66 KSEW 200341
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
841 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/...The forecast remains
largely on track tonight, with no updates needed to the short and
long term. The previous discussion follows below, with updates
made to the aviation and marine sections. 14
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 continues across the terminals this evening
(only exception is reduce visibilities due to haze from the Bear
Gulch Fire drifting into the south interior - affecting KSHN and
KOLM). Guidance continues to hint at a push of low stratus Saturday
morning. Highest confidence of seeing IFR/LIFR ceilings is along the
coast, but it remains possible that 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. Winds will decrease out of the north tonight (becoming
light and variable under 5 kt in most spots), and will pick out of
the southwest in the afternoon. Gusts up to 20 kt are possible, with
rain arriving after 03-06Z.
KSEA...VFR will persist through the TAF period. Winds relaxing this
evening out of the north - will be light and variable overnight and
become S/SW Saturday morning after 10z-12z. An increase up to 7-10
kt in the afternoon/evening is expected with gusts to 18-20 kt
possible. Precipitation chances increase above 30% past 06Z Sunday.
29/HPR
&&
.MARINE...High pressure will remain over the waters today and
weaken tonight as a frontal system approaches the coastal waters.
Patchy dense fog is possible in the coastal waters tonight, but
probabilities of widespread fog producing visibilities less than a
mile remained largely below 50%, though satellite shows possible
stratus developing just southwest of the Grays Harbor Bar. Will
continue to monitor the potential for a future dense fog advisory
tonight.
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/HPR
&&
.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