Winlock, Washington Weather Forecast Discussion

849
FXUS66 KSEW 210325
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
825 PM PDT Sat Sep 20 2025
.SYNOPSIS...A frontal system moving through the area late
tonight into Sunday morning will bring widespread rain, breezy
winds, and cooler temperatures. Drier weather will return
Monday and linger through midweek, followed by what looks to be
typical late September weather for the second half of the week.
&&
.SHORT TERM /TODAY THROUGH MONDAY NIGHT/...Latest radar shows rain
moving into the North Coast this evening with the approaching
frontal system offshore. Expect rain to continue to spread inland
during the overnight hours, with the more widespread precipitation
likely making it into the interior lowlands between 3-6am. Southerly
winds will become breezy as the front moves across the area,
generally persisting between 20-25 mph-though a few spots up north
in the vicinity of Bellingham may see some wind gusts approach 30
mph. The overall forecast remains largely on track tonight, with
no updates needed to the short and long term. The remainder of the
previous discussion follows below, with updates made to the
aviation and marine sections. 14
Increasing cloud cover will continue to spread inland this
evening with widespread rain on track to move onshore late this
evening and through the interior by early Sunday morning. The
heaviest rain expected along the coast and Olympics from 11pm to
2am and 3am to 6am for the interior lowlands. Showers may stick
around into Sunday morning especially over the Cascades. High
resolution ensembles continue to highlight the formation of a
convergence zone later Sunday morning, keeping precipitation going
over the metro area into the Cascades into Sunday afternoon. With
the trough axis directly overhead by Sunday afternoon, there may
be just enough instability for a lightning strike or two, but
overall the probability is low (10-15%) with the best bet being
with the convergence zone. Precipitation amounts through Sunday
afternoon remain in the ballpark of 0.5 to 1 inch across the
mountains and the Pacific coast, with the interior around 0.25-0.5
inch. More than anything this will bring a temporary reprieve for
the active fires in the area and help with the air quality.
Sunday`s high temperatures will remain quite cool, in the mid to
upper 60s with lows in the 40s to near 50 in the metro/urban areas
going into Monday morning. Areas of fog can also be expected
Monday morning. Building upper level heights behind the upper
level trough will help mostly clear skies and more seasonable
temperatures return Monday afternoon, with highs a few degrees on
either side of 70.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...Upper level ridging looks
to remain in place into Tuesday and Wednesday, allowing for a
gradual warm-up, generally back into the mid to upper 70s with a
few spots at or near 80. Lows remain in the 50s. The pattern
looks to shift around mid-week, opening the door for the
potential for a systems to brush the area late in the week into
the weekend. This will likely bring more typical late September
temperatures with periods of potential precipitation.
&&
.AVIATION...A cold front will bring widespread rain tonight across
all terminals. The first bands have arrived for coastal terminals
(the first bands have reached the coast this evening where MVFR
conditions are currently present). Clouds will slowly lower ceilings
tonight from west to east, with clouds taking longer to fill in this
evening in the interior. Rain will reach the interior terminals
likely after 09Z (at its current pace). The rain may be heavy enough
to lower visibilities down to IFR at times. Gusty southwest winds up
to 20-25 kt are expected ahead of the showers (with a couple higher
gusts possible north of Whidbey Island). Post front, a convergence
zone may keep showers going between KBFI and KPAE through the
morning. Ceilings and visibilities are expected to lower further
post front Sunday up to 18Z. Mist/low ceilings are expected post-
front Sunday morning, with generally MVFR in the central Puget Sound
terminals, IFR/LIFR to the north towards the Strait of Juan de Fuca
and the south interior/coast, with clearing taking place 18-22Z from
east to west (though clouds may linger along the coast longer).
Winds will become northwest for most terminals Sunday afternoon
(northeast in Puget Sound) 4-8 kt, decreasing in the evening.
KSEA...Still remains VFR this evening with lower clouds slowly
filling in. Rain is expected to arrive (at its current pace) just
past 09Z, lasting through 15Z. Lower VIS is possible with the
heavier showers. Convergence zone may keep showers going to the
north through 18Z. Ceilings to lower to MVFR with the rain pushing
through, with mist mixed in. Winds will pick up prior to the rain
arriving, with 20-25 kt gusts out of the southwest likely. Clearing
on Sunday will take place 18-22Z, with winds beginning to shift to
the northeast after 20Z 4-8 kt, but will decrease in the evening.
HPR
&&
.MARINE...Surface high pressure will weaken tonight as a cold
frontal system pushes through area waters tonight through Sunday
morning. Winds will increase across all area waters as the front
passes over the waters, for which Small Craft Advisories have been
issued. A strong push of post-frontal westerlies is expected along
the Strait of Juan de Fuca Sunday morning through the afternoon for
the central and eastern portions. The strongest winds will be in the
central portion, where wind gusts may reach low-end gales. Winds
will gradually subside late Sunday night. In addition, there is a
small chance of thunder (15%-20%) for the coastal waters Saturday
night. Seas will build tonight into Sunday to 8-10 ft for the
coastal waters.
High pressure will build over the waters late on Sunday into Monday
and will weaken slightly as a weakening front moves over the waters
on Tuesday. High pressure will rebuild again over the waters on
Wednesday.
29/HPR
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory until 3 AM PDT Sunday for West Entrance
     U.S. Waters Strait Of Juan De Fuca.
Small Craft Advisory until 1 PM PDT Sunday for Central U.S.
     Waters Strait Of Juan De Fuca.
Small Craft Advisory from 11 PM this evening to 1 PM PDT Sunday
     for East Entrance U.S. Waters Strait Of Juan De Fuca.
Small Craft Advisory from 11 PM this evening to 9 AM PDT Sunday
     for Admiralty Inlet-Northern Inland Waters Including The
     San Juan Islands-Puget Sound and Hood Canal.
Small Craft Advisory until 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