Forest, Washington Weather Forecast Discussion

618
FXUS66 KSEW 221044
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
344 AM PDT Mon Sep 22 2025
.SYNOPSIS...Conditions will trend drier and warmer across
Western Washington for the first half of the week. Warmest days
look to be Tuesday and Wednesday, with typical late September
weather with near normal temperatures and potential for
precipitation Friday and especially into the weekend.
&&
.SHORT TERM /TODAY THROUGH WEDNESDAY/...A few patches of fog and
low stratus already forming around Hood Canal and the South
Sound, as well as southwestward along the lower Chehalis. This
is hardly surprising given the light winds, recent rainfall,
and clearing skies across the region. Expect these areas to
increase a bit more toward daybreak, but clear fairly quickly
through the morning. Otherwise, heights begin to rise as the
previous system departs the area and the next upper ridge begins
to build into place. Temperatures warm to around 70 this
afternoon through the interior, with a few more degrees driving
afternoon temperatures into the mid 70s Tuesday as a thermal
trough builds northward and the flow turns weakly offshore. Dry
and warm conditions continue into Wednesday with high pressure
overhead.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...Ensemble guidance
continues to favor a shift in the pattern later in the week to
allow more zonal flow to develop over the northeastern Pacific
as the ridge weakens. While there`s still some spread as to if
the next upstream trough is able to move over the Pacific
Northwest, there will at least be some chances for rain starting
around Friday. That said, around half of the ensemble members
would keep much of the area dry into at least the start of the
weekend. Regardless, a return of typical late September weather
with near normal temperatures appears the most likely scenario
at this time.
&&
.AVIATION...Northwest flow aloft will become westerly late today as
an upper level ridge builds into the region. Light surface flow will
turn northerly as thermally induced low pressure south of the area
begins to expand northward. The combination of light surface winds
and low level moisture from recent rains will lead to areas of
LIFR/IFR in fog and/or stratus across the lowlands. This will
scatter out to VFR most areas by around 18Z-20Z.
KSEA...Light surface winds and mostly clear skies early this morning
favor the formation of low clouds by around 12Z persisting into mid-
morning before scattering. VFR is expected thereafter. Surface winds
light and variable this morning will become north/northwesterly 5 to
7 knots this afternoon and evening.
27
&&
.MARINE...Surface high pressure will rebuild across the waters
today. Thermally induced low pressure will expand northward along
the coast on Tuesday turning the flow northerly or weakly offshore.
Onshore flow will resume around midweek as high pressure rebuilds
offshore behind a frontal system passing well to the north of the
area. A dissipating front will reach the area at the end of week.
27
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...None.
&&
$$

NWS SEW Office Area Forecast Discussion