Napavine, Washington Weather Forecast Discussion

373
FXUS66 KSEW 242138
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
238 PM PDT Wed Sep 24 2025
.SYNOPSIS...Zonal flow will bring in more fall-like conditions
across western Washington through the remainder of the week, with
cooler temperatures and periods of cloudy skies. Periods of
showers are possible Friday and Saturday before more widespread
rain enters the region on Sunday and Monday. Unsettled and cooler
conditions are favored to continue into next week.
&&
.SHORT TERM /TONIGHT THROUGH SATURDAY/...An upper level ridge over
the western US will flatten throughout the remainder of the week
as an upper level trough moves inland over British Columbia. Zonal
flow will develop over western Washington by the afternoon today,
generating onshore flow that will bring periods of cloudy skies
and cooler temperatures. This shift to westerly winds will also
help to push any remaining smoke to the east side of the Cascades
by this evening. While temperatures today are on track to reach
the mid 70s across much of the lowlands, stronger onshore flow
Thursday will lower temperatures by several degrees, with most
areas struggling to surpass the mid 60s.
As a deepening upper low in the Gulf of Alaska advects moisture
towards the west coast of Canada, some shower activity may graze
the northern portion of western Washington on Friday and Saturday,
particularly along the northern Olympic Peninsula, over the San
Juan Islands, and northern interior. Rainfall amounts will
generally be light, with the highest rain likely over the
northwestern Olympic Peninsula. Temperatures Friday and Saturday
will
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...A frontal system is on
track to cross the region on Sunday, bringing widespread rain and
cooler temperatures to the region that will linger into next
week. Between Sunday and Monday, ensembles are showing potential
for a half inch or more of rainfall across the lowlands and up to
2 to 3 inches of liquid over the mountains. Another trough will
follow close behind, maintaining chances for rain through the
middle of next week. By the beginning of next week, temperatures
will peak in the low to mid 60s across the lowlands.
15
&&
.AVIATION...Westerly flow aloft with a frontal system passing
north of our area and an upper level ridge weakening. Light
offshore flow in the lower levels will gradually turn onshore
later in the evening. VFR at all terminals this afternoon with
some smoke and haze aloft. Onshore flow will bring marine stratus
through the coastal areas later this evening for IFR/LIFR
conditions, along with stratus spreading through interior
locations for a a mix of MVFR/IFR conditions by Thursday morning.
Lowered conditions over the interior will burn off by 17-18z,
rebounding back to VFR for most of the area.
KSEA...VFR conditions this evening with surface winds N/NE 6 to 8
knots, shifting more northwesterly overnight. MVFR/IFR stratus is
likely at the terminal generally around 09-15z, with a 40% chance
of MVFR conditions and a 20% chance of IFR conditions. Stratus
looks to burn off by 18z, resuming VFR conditions throughout the
remainder of the day. Surface winds shifting SW/S briefly in the
morning before turning NW by the afternoon.
Mazurkiewicz
&&
.MARINE...Surface high pressure over the coastal waters this
afternoon will lead to an increase in onshore flow later this
evening. Increasing northwesterlies over the coastal waters will
keep the small craft advisory in place for the outer coastal
waters, and the southern inner coastal waters for a combination of
winds and choppy seas. Onshore flow continues into Thursday where
a westerly push down the Strait of Juan De Fuca may warrant a
small craft advisory depending on the strength of the winds. A
stronger front looks to reach the area Sunday night into Monday
which could yield potential impacts for the area waters including
headlines.
Combined seas 7 to 9 feet this afternoon decreasing briefly
Thursday evening before building back up to 8 to 11 feet by Friday
evening and hovering throughout first part of the weekend.
Mazurkiewicz
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory until 11 AM PDT Thursday for Coastal Waters
     From Cape Flattery To James Island 10 To 60 Nm-Coastal
     Waters From James Island To Point Grenville 10 To 60 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