Brier Weather Station
Latitude N 47° 46' 49" Longitude W 122° 16' 48" Elevation 341 ft
065
FXUS66 KSEW 290251
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
746 PM PDT Fri Aug 28 2026
.SYNOPSIS...
An upper-trough will swing another weather system into the region
tonight into Saturday. Brief ridging is expected to begin next week
but an active pattern is forecast to return by Tuesday as additional
troughing sets up. A well-ogranized system looks to arrive around
midweek with the potential for widespread rainfall. Cooler than
average temperatures are favored throughout this time.
&&
.SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...
Latest radar showing some weak echoes off the NW tip of the Olympic
Peninsula this evening lining up with the weak front models will
push into the area tonight and Saturday morning. Also present could
be the very beginning of the expected PSCZ over the southern islands
and only just now starting to creep into western portions of Skagit
and Snohomish counties. This activity is good indication that
inherited forecast is on track with no need for evening updates. For
additional forecast details, please refer to the Previous Discussion
section below. 18
From Previous Discussion...We`re in between systems here across
western Washington as the next disturbance looms off the BC coast.
Conditions are mostly dry but that`ll change later tonight into
early Saturday morning. A convergence zone is slated to develop this
evening, mainly Snohomish County northward before meandering
southward into Saturday. The aforementioned upper-low will also
track across the area during this time as rain showers become
widespread. Overnight lows will range throughout the 50s with a few
spots in the upper 40s.
Active weather into Saturday as the upper-low not only bring
showers but the potential for thunderstorms. HREF has 200-400
j/kg of surface based CAPE analyzed across western Washington
Saturday afternoon. Mean 700-500 mb lapse rates are also around
7 C/km, indicative of some degree of instability. These
parameters in place with dynamics provided by the upper-low has
allowed for parts of the CWA to placed in the SPC`s convective
outlook for general thunderstorms. The threat will end Saturday
night as an upper-level ridge enters the fray with conditions
drying out. Can`t rule out areas of fog developing into
Sunday morning with lingering surface moisture and lighter
winds. Ridge axis is modeled to pass directly overhead on Sunday
as morning clouds give way to mostly clear skies in the
afternoon. However, the flow aloft will trend more out of the
southwest on Sunday night as the next upper-low digs over the
NE PAC. High temperatures in the 60s to lower 70s throughout the
short term with overnight lows in the mid 40s to lower 50s.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
Conditions will remain drier on Monday as the upper-ridge exits
the region. Then, the next upper-trough will continue to dig
over the NE PAC and sit right off the PNW coast by Monday
evening. Given latest guidance, it`s associated upper-low will
track south of the area into Oregon but we could get side swiped
with showers on Tuesday. Then, a more organized disturbance is
slated to arrive Wednesday and possibly stalling over the region
into Friday. This feature has the potential to bring widespread
rainfall and well-below average temperatures as the region will
begin to get a taste of fall with highs only in the 60s.
&&
.AVIATION...
Southwesterly winds will become cyclonic Saturday evening as an
upper level low moves directly overhead of western Washington. VFR
conditions will continue through this evening before a weak frontal
system moves across the area overnight, bringing a return to MVFR to
IFR ceilings across the area as well as chances for scattered
showers. IFR cigs are most likely along the coast, with chances for
IFR cigs elsewhere under 20%. Expect cigs to slowly lift and break
up through the late morning into the early afternoon on Saturday.
S/SW winds will continue around 5-10 kt, with some gusts to 15-20 kt
possible this evening through the Strait of Juan de Fuca and the
Chehalis gap. Winds look to switch to northerly this evening through
Puget Sound for the Seattle area terminals. Winds then switch back
to southerly overnight and remain southerly into the daytime
Saturday.
KSEA...VFR conditions will continue through late this evening. A
weak front moving through will lower ceilings to MVFR after around
08-12Z Sat and will again slowly lift and scatter into Saturday
afternoon. S/SW winds up to around 6-8 kt will turn more NW to N
this evening, around 00-02Z Saturday. Winds switch back to southerly
after around 09Z Sat. 33/62
&&
.MARINE...
A weak frontal system will move through the area waters tonight,
which will maintain northwesterly winds through the coastal waters
through Saturday, as well as bring pushes of westerlies down the
Strait of Juan de Fuca tonight and Saturday night as well. A
Small Craft Advisory is in effect for the Strait tonight, and
another will likely be needed tomorrow. Systems will pass by
well to the north on Sunday and Monday, keeping winds fairly
light across the area. A stronger low pressure system look to
move through the area waters Tuesday into the middle of next
week, which may bring increased winds to much of the coastal
waters and higher seas through the middle of next week.
Seas remain 4 to 6 ft through Tuesday, then increasing to around 7
to 9 ft by the middle of next week.
62
&&
.FIRE WEATHER...
Onshore flow, cooler temperatures, and increasing RHs will persist
through next week. An upper level low pressure system will bring
chances for showers this evening through Saturday evening. In
addition, there still remains an isolated threat for thunderstorms
Saturday afternoon mainly over the Northern and Central Cascades. If
a thunderstorm develops, wetting rains are unlikely and lightning
may pose a hazard that could lead to new fire starts. Erratic and
gusty outflow winds over existing fires could also be problematic.
Weather system next Wednesday has a good chance of producing wetting
rains along the coast and over the mountains. JBB/Felton
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory until midnight PDT tonight for Central
U.S. Waters Strait Of Juan De Fuca-East Entrance U.S.
Waters Strait Of Juan De Fuca.
&&
$$
NWS SEW Office Area Forecast Discussion