Brier Weather Station
Latitude N 47° 46' 49" Longitude W 122° 16' 48" Elevation 341 ft
288
FXUS66 KSEW 121757
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
1057 AM PDT Tue May 12 2026
.SYNOPSIS...
A lingering ridge of high pressure will bring one more day of warm
temperatures to western Washington today. A transition to onshore
flow and cooler conditions will take place on Wednesday along with a
chance of some precipitation. Cooler and unsettled conditions will
continue into the weekend as a trough of low pressure over the
Northeast Pacific sends a series of weak frontal systems across the
area.
&&
.SHORT TERM /TODAY THROUGH THURSDAY/...
Generally clear skies over W WA this early morning although seeing
some high clouds starting to move in from the far SW corner of the
CWA. Some low-level clouds are possible inland from the coastline,
although their eastward extent is pretty limited.
One last day under the ridge will see daytime highs a few degrees
warmer than yesterday with widespread upper 70s to lower 80 expected
throughout the interior lowlands. Locations along the coast and in
the islands will benefit from their proximity to water with highs in
these spots much milder in the upper 60s to around 70. The ridge
pushes eastward late this afternoon/early this evening allowing for
an onshore push. While the most obvious change will be the cooling
of temperatures, the incoming upper level trough tonight and
associated moisture could give rise to evening and overnight
showers. Best chances of this seem to be near the Cascades and
associated foothills where orographics will give a boost to the
incoming instability, but the lower end PoPs for these showers
extends to the eastern half of the Olympic Peninsula. A slight
chance for thunderstorms is present over the far southern portion of
the Cascades, which lines up with latest SPC thoughts of general
thunder...although this is more of a concern for down in PQRs CWA.
Wednesday sees the upper low traverse the area, keeping showers in
the forecast and significantly cooler temperatures...mainly in the
lower 60s. Best chance for rain is largely confined to east of the
Sound, however PoPs are present area-wide for much of the day.
Thursday sees a shortwave ridge quickly enter and exit the area.
While this will limit PoPs over the area, it does not completely
eliminate the chance for showers in some locations...again with a
preference over the northern two-thirds of the Cascades. Temps warm
slightly...mainly a couple of degrees at best...as lowland highs
remain in the lower 60s...although some spots may nudge into the mid
60s.
18
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
An alternating series of troughs and shortwave ridges for the
remainder of this week will keep temperatures cool...upper 50s to
lower 60s for daytime highs...and the chances for rain elevated. A
broad trough begins to impact the area starting Friday and at the
time of this writing models seem to be favoring some level of
instablilty over W WA...resulting in a widespread slight chance for
thunderstorms in the afternoon and evening hours. While this trough
ejects Saturday morning, embedded shortwaves in the upper flow will
keep showers in place for much of the remainder of the day. How
quickly this moisture is pushed out of the area appears to be a
point of contention in the long range model data. While there is
consensus on an upper level ridge setting up for the remainder of
the forecast period, the amplitude of said ridge will play a role in
how quickly dry conditions return, thus introducing some
uncertainty. Latest NBM output suggests moisture...and thus
showers...lingering Sunday before tapering off on Monday. This
transition will also help temperatures find their footing as daytime
highs Monday get into the mid to upper 60s.
18
&&
.AVIATION...
High pressure across the region today with VFR conditions area-
wide. Increasing southwest flow aloft later today. Winds become
southerly this afternoon and increase a bit, with some gusts to
15-20 kt possible late this afternoon. There is a 60-80% chance
of showers passing through the terminals east of Puget
Sound/Cascades late this evening/Wednesday morning, with another
line of showers along the coast later Wednesday morning. There
is also a 20% chance of thunder in the Cascades, generally from
Mt. Rainier southward. Expect mostly MVFR ceilings overnight. Winds
to remain out of the southwest Wednesday, with a couple spots
becoming breezy later in the day.
KSEA...VFR during the day, with light northwest winds this
morning becoming southerly this afternoon. Speeds increase to
8-12 kt later afternoon with gusts to 20 kt through evening.
Showers likely arrive after 06z Wednesday through the terminal
area, decreasing through the day Wednesday.
&&
.MARINE...
A ridge will transit east over the waters today over a thermal
trough at the surface. Winds will return to onshore later this
afternoon as a trough/front passes over the waters this evening into
Wednesday. The interior waters have the highest chance of seeing
showers Wednesday morning. Pushes through the Strait of Juan de Fuca
will resume with this system passing through this evening, with the
strongest one expected Wednesday evening with a marginal chance of
wind gusts approaching gale force in the central/east sections. The
southern portion of the Puget Sound waters and the north interior
waters have a medium chance of seeing gusts over 20 kts for rougher
small craft conditions. Seas will hold around 4-6 ft through the
week, with a brief bump to 6-8 ft with the midweek system.
HPR
&&
.HYDROLOGY...
The daily hydrology discussion has ended until the
start of the next rainy season; it will only be updated during
this time as needed.
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...None.
&&
$$
NWS SEW Office Area Forecast Discussion