Brier Weather Station
Latitude N 47° 46' 49" Longitude W 122° 16' 48" Elevation 341 ft
983
FXUS66 KSEW 301752
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
1052 AM PDT Wed Sep 30 2026
.UPDATE...short term aviation update for impactful ceilings at
metro terminals.
&&
.SYNOPSIS...
A frontal system will move out of Western Washington
into this evening. High pressure builds aloft over the Pacific
Northwest Thursday and Friday, with just a slight chance of
precipitation. The upper ridge further builds over the weekend
for drier, warmer conditions.
&&
.SHORT TERM /TODAY THROUGH FRIDAY/...
Drier conditions across Western Washington this morning as a few
lingering light showers continue to taper this morning. With the
abundant low-level moisture from yesterday`s rainfall and
decreasing winds, expect to see the spatial coverage of fog to
increase this morning toward daybreak. Low clouds gradually
decrease through the day with at least partial sunshine for the
afternoon. Not much change in the overall picture through
Thursday. With the flow remaining zonal, there`s the potential
for enough of an impact from the next disturbance clipping the
far north as it passes across southern B.C. This brings some
rain chances to the northern portions of the interior (mostly
Whatcom/Skagit counties), but even for the areas that see rain
it should remain quite light. As this disturbance exits the
region on Friday, a few light showers may linger in the North
Cascades, but dry conditions hold for most of the area.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
Ensemble guidance remains in fairly strong agreement for the
weekend into early next week. the pattern would likely
favor a return of high pressure and some light offshore flow.
This could yield a somewhat mild start to October, with
temperatures into the lower to mid 70s Sunday. The return of
more onshore flow would return early next week as the high
pressure nudges slightly eastward, bringing temperatures back
down closer to 70 for daytime highs with the greater marine
influence. Overall, though, mild and dry conditions expected for
the long term period.
&&
.AVIATION...
Lingering MVFR to IFR conditions with fog and or low stratus
that developed just before daybreak this morning. The lower
ceilings stubbornly affecting KPAE have actually pushed further
south into KBFI and KSEA, bringing a brief period of MVFR
conditions with ceilings 1300-1500 ft. The expectation remains
that conditions will gradually improve through midday to VFR
levels at these locations as the boundary layer warms up. All
other locations will remain VFR through the evening. Expect a
similar scenario Thursday AM with elevated odds of MVFR to IFR
conditions for a few locations, especially KBLI, KOLM and KPAE.
Calm to light northerly winds early this morning will increase
to 6-8 kt through the afternoon then ease late evening.
KSEA...An area of stratus well to the north of the terminal has
shifted south bringing 1300 to 1500 ft ceilings to the terminal
briefly this morning. MVFR conditions will linger through 19/20Z then
lift and scatter quckly to VFR levels through the afternoon and
evening. Uncalibrated probabilities from LAMP for fog/low-
ceilings Thursday morning remain less than 5%. Light NE winds
early this morning will back to the NW in the afternoon and
increase to 6-8 kt. Winds will ease this evening, veer back to
the NE at 5 kt or less.
&&
.MARINE...
Seas subsiding over the coastal waters this week. Meanwhile,
building high pressure over the waters with a thermal low
pressure building north along the coast by the weekend. This
will induce northerly to weak offshore flow over the waters, but
speeds aren`t expected to be particularly strong. This will
maintain seas generally 3-6 ft over the coastal waters and
conditions short of advisory thresholds.
&&
.FIRE WEATHER...
Mostly dry conditions through the week ahead with additional
wetting rain not expected. A few light showers across the north
may develop with a passing disturbance late Thursday into
Friday. Otherwise, attention turns to a warmer period with
temperatures well into the 70s this weekend under stronger high
pressure. This may bring a brief switch to light offshore flow
as a thermal trough builds north over the region. This looks to
shift eastward for a return to onshore flow and closer to normal
conditions early next week.
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...None.
&&
$$
NWS SEW Office Area Forecast Discussion