Brier Weather Station
Latitude N 47° 46' 49" Longitude W 122° 16' 48" Elevation 341 ft
112
FXUS66 KSEW 191555
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
855 AM PDT Wed Aug 19 2026
.SYNOPSIS...Weak upper level ridge with light onshore flow in
the lower levels through Thursday. Upper level low approaching
from the southwest Friday will move into the coastal waters
Saturday. Shower chances increasing Friday night into Saturday
with thunderstorms possible. Low moves by to the north Saturday
night. Upper level ridge rebuilding Sunday and Monday will move
east Tuesday as an upper level trough develops off the coast.
&&
.SHORT TERM /TODAY THROUGH FRIDAY/...Satellite imagery shows
low clouds along the coast have already moved through the Lower
Chehalis Valley and down the Strait of Juan de Fuca to the Puget
Sound at 3 am/10Z. Just some high clouds over the remainder of
the area. Temperatures were in the 50s and lower 60s.
Stratus a little further east this morning versus the last
couple of mornings and will move east of Puget Sound around
sunrise. Like the other mornings the layer is shallow with top
reports around 1000 feet msl. With the layer being so shallow
locations in the lowlands from Snohomish county southward will
see some patchy fog through mid morning. Layer retreating back
to the coast late morning/midday with afternoon sunshine for the
interior. Clouds hanging right along the coastline in the
afternoon. Highs inland in the 70s and lower 80s, along the
coast in the mid and upper 60s.
Not much change in the pattern overnight into Thursday. Low
level onshore flow a touch weaker making it harder for the
stratus to get east of Puget Sound for very long Thursday
morning. Slightly shallower marine layer combined with slight
warming aloft adding a couple of degrees to the highs. Lows in
the 50s. Highs in the mid 70s to mid 80s inland and near 70
coast.
Pattern starts to change Thursday night into Friday. Upper level
low well offshore approaching the area. Upper level flow
becoming southerly sending middle and high level clouds into
Western Washington. Increasing low level onshore flow Friday
afternoon looks to be too late to make much of a difference in
the temperatures. Lows again in the 50s. Highs Friday in the
70s and lower 80s interior and mid to upper 60s coast. Felton
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...Extended models in
much better agreement in the 00z run. Upper level low continuing
to approach Western Washington with the low over the coastal
waters Friday night. System spinning out of the low moving
through late Friday night into Saturday morning with scattered
showers and a slight chance of thunderstorms. Low continuing to
slowly move northeast Saturday night and Sunday with the shower
chances confined to the northern portions Sunday. Upper level
ridge rebuilding later Sunday into Monday. The ridge will shift
east Tuesday with an upper level trough developing off the
coast.
Highs Saturday much below normal, in the 60s and lower 70s. A
little warmer Sunday but still below normal, lower 60s to mid
70s. Highs warming back to normal, in the 70s interior and mid
to upper 60s coast Monday and Tuesday. Lows in the 50s through
the period. Felton
&&
.AVIATION...Light southwesterly flow aloft with weak low level
onshore flow through Thursday. Mix of IFR/LIFR ceilings continue
this morning with pockets of lower visibilities down to a
quarter of a mile in the Kitsap Peninsula and east Strait of
Juan de Fuca. Depth of the marine layer is thin and has already
started lifting this morning - will be on track to scatter from
19-20Z. Winds today starting out of the southwest around 5 kt or
less, shifting to the northwest in the afternoon before
switching back to the southwest again overnight under 5 kt.
Stratus likely to move back inland overnight, with LIFR most
likely from north Puget Sound/Kitsap Peninsula westward. Some
mist/fog may mix in too.
KSEA...Stratus has lifted to IFR as of 15Z, and is on track to
scatter around 18-20Z this morning. SW winds around 5 kt will shift
to the northwest 4-8 kt in the afternoon/evening, becoming light out
of the southwest overnight/Thursday morning. Odds of the marine
stratus Thursday morning are similar to the past few mornings,
elevated chance of IFR/LIFR at 20-30%, but odds of low visibilities
remain less than 5%.
HPR
&&
.MARINE...Broad surface high pressure over the waters will
weaken Friday. A weak surface low will move into the coastal
waters Saturday then dissipate Saturday night. High pressure
will rebuild over the waters Sunday.
Small craft advisory winds in the Central Strait Friday night
otherwise winds remaining below 20 knots through the period.
Seas 3 to 5 feet for the most part through the weekend. Felton
&&
.FIRE WEATHER...Low level onshore flow creating good humidity
recoveries overnight into the early morning hours will keep fire
weather concerns at a minimum through Thursday.
System moving through the region Friday night into Saturday
will elevate fire weather concerns. This system could produce
thunderstorms mainly over the Olympics and Cascades. Any
thunderstorms that develop may be capable of producing locally
wetting rains alongside gusty and erratic outflow winds and
abundant lightning.
Fire weather concerns decrease Sunday with the system to the
north and high pressure building into the area. Low level
onshore flow Sunday through Tuesday with morning stratus and
afternoon sun, near normal temperatures, and generally calm
winds. Felton
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...None.
&&
$$
NWS SEW Office Area Forecast Discussion