Brier Weather Station
Latitude N 47° 46' 49" Longitude W 122° 16' 48" Elevation 341 ft
719
FXUS66 KSEW 041008
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
308 AM PDT Fri Sep 4 2026
.SYNOPSIS...
Upper level low along the Central Oregon coast this morning will
hardly move through Saturday morning. The low will drift north
over Western Washington Saturday afternoon and remain in the
vicinity until moving east Sunday night into Monday morning.
Dry northwesterly flow aloft later Monday into Tuesday. A weak
system will brush the area Thursday.
&&
.SHORT TERM /TODAY THROUGH SUNDAY/...
Satellite imagery shows upper level low along the Central Oregon
coast early this morning. Showers spinning around the low
moving off the Cascades into the lowlands of Skagit and
Snohomish county. Doppler radar also indicating isolated showers
over the south Puget Sound. Temperatures at 3 am/10Z under
mostly cloudy skies were in the upper 40s to mid 50s.
So far so good with the model predictions for where the low
would go the last 24 hours. Low not moving much in the next 24
hours staying over Western Oregon. Once this current batch of
showers rotates through early this morning a little break in the
activity for the remainder of the morning. Air mass becoming
somewhat unstable in the afternoon with showers developing over
the higher terrain. Light east southeasterly flow aloft will
try and push the showers into the lowlands late this afternoon
into the evening hours. Winds at 700 mb and 500 mb 10 knots or
less will make it hard for the showers to get all the way to the
Puget Sound. With the light flow aloft any convection that does
form has the potential to produce at least a brief heavy
downpour with the cells moving slowly. Shower activity drying up
in the evening hours with mostly cloudy skies overnight. A
little bit of sun today pushing highs in the 60s and lower 70s.
Lows tonight in the mid 40s to mid 50s.
Low starts to drift north Saturday morning ending up over
Western Washington Saturday afternoon. Like today, showers
developing over the higher terrain by late morning will try and
float down into the lowlands in the afternoon and early evening
hours. Light flow aloft continuing with the low overhead making
it most likely the convection over the Cascades only gets to
the Cascade foothills with the activity over the Olympics not
getting all the way to the ocean. Showers dissipating in the
evening with partly cloudy skies into Sunday morning.
Persistence a good forecast for the temperatures Saturday and
Saturday night. Highs maybe a couple of degrees warmer than
Friday.
Low weakening but remaining in the vicinity Sunday. Could still
see a shower over the Cascades especially the South Cascades in
the afternoon otherwise just partly cloudy skies. Highs in the
upper 60s to mid 70s. Felton
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
Model solutions have been in good agreement for a few runs that
the low kicks out to the east Sunday night and Monday. Dry
northwesterly flow aloft developing over the area Monday will
continue into Tuesday. Western Washington in a lull Wednesday
with a weak upper level low developing well to the southwest
and a weak system starting to slide down the British Columbia
coast. System brushing the area Thursday for a slight chance of
showers. Temperatures near normal through the period with mostly
sunny days and partly cloudy nights. Highs upper 60s to mid
70s. Lows in the upper 40s to mid 50s. Felton
&&
.AVIATION...
Variable flow aloft this morning as upper level low
moves very slowly over W WA. Surface winds at most terminals also
light and variable with speeds less than 5 kts. This looks to
persist for most terminals, although some could see a shift to
southerly winds this morning with speeds remaining light. Direction
will shift to west or northwesterly this afternoon. Terminals on the
east side of the Sound will see winds turn again more northerly in
the evening. Speeds for all terminals will increase some, generally
ranging 4-8 kts to finish the TAF period.
Widespread VFR conditions this early morning, although isolated
patches of MVFR to IFR conditions are present along the coast, over
the islands and in the SW interior. Cigs may lower a little more
this early morning, however nothing indicating that bases will dip
into lower flight categories. VFR conditions expected to persist
throughout the TAF period as cigs lift further in the afternoon.
KSEA...VFR conditions this early morning and are expected to persist
as per above discussion. Models had suggested the prospect, albeit a
minor one, of low clouds or fog in the 12-15Z time frame, but at
this time, while there are FEW to SCT clouds around 2500, clouds at
this level remain broken up enough to keep flight category
persistent. Southerly winds this morning and early afternoon
generally 4-8 kts becoming northwesterly mid-afternoon, then north
to northeasterly tonight with similar speeds.
18
&&
.MARINE...
Marine forecast remains uneventful as winds and seas remain below
any sort of headline criteria. Broad low pressure remains in place,
with showers and a few thunderstorms possible again today, which
could bring isolated gusty outflow winds. Otherwise, northerly winds
develop over the waters Saturday through the start of next week. A
marginal westerly push through the Strait of Juan de Fuca around
Monday looks to be the next potential period of advisory strength
conditions. Seas currently 4 to 6 ft, expected to ease just a little
more this afternoon, down to 3 to 5 kt...and will remain there
through the first half of next week.
18
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...None.
&&
$$
NWS SEW Office Area Forecast Discussion