Brier Weather Station
Latitude N 47° 46' 49" Longitude W 122° 16' 48" Elevation 341 ft
842
FXUS66 KSEW 021014
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
314 AM PDT Wed Sep 2 2026
.SYNOPSIS...
Upper level low moving out of the Gulf of Alaska moving down
British Columbia coast to the Washington coastal waters
Thursday. Strong for early September cold front associated
with the low moving through late this afternoon and early this
evening bringing rain and gusty winds. The upper level low will
remain in the vicinity through the weekend for cool and
unsettled weather. Possible drying trend Monday and Tuesday as
the low moves out of the area.
&&
.SHORT TERM /TODAY THROUGH FRIDAY/...
Satellite imagery shows upper level low just southwest of Haida
Gwaii with the associated cold front off the coast near 128W.
Rain started on the North Coast in the last hour. Slightly
unstable air mass ahead of the front with doppler radar
indicating some light showers over the foothills and Cascades.
Temperatures at 3 am/10Z were in the mid 50s to lower 60s.
Everything still looks on track this morning. Upper level low
will continue to drop south today. Cold front off the coast
becoming slightly negatively tilted. This will slow down the
eastward progress of the front. Rain spreading inland west of
Puget Sound this morning and over the remainder of the area
this afternoon. Slight chance of thunderstorms well ahead of the
front this morning with the unstable air mass. South to
southeast winds increasing along the coast and over the
Northwest Interior and Admiralty Inlet later this morning. Windy
conditions, 20 to 35 mph, continuing into the afternoon hours.
Front reaching the coast late this afternoon. The wind
advisories for the coastline, Northwest Interior and Admiralty
Inlet remain in effect. Highs in the lower to mid 60s.
Front moving through the interior early this evening with steady
rain changing to showers. Breezy conditions just ahead and with
the front. Winds easing post frontal along the coast early
evening and over the interior before midnight. Lows in the mid
40s to mid 50s.
Upper level low off the coast Thursday will slowly drift inland
Friday over Oregon. Relatively cool and unstable air mass over
the area keeping showers in the forecast with a slight chance of
thunderstorms in the afternoons with a little daytime heating.
Highs remaining in the 60s. Lows Thursday night in the mid 40s
to lower 50s. The last time Seattle had a low in the 40s was
June 8th ( 49 degrees ). Felton
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
Models in general agreement with the upper level low remaining
in the vicinity through the weekend. This is not a scenario the
models are going to handle very well as far as the exact
placement of the low. At this point will have to keep at least a
chance of showers in the forecast. Temperatures slowly warming
with highs in the mid 60s to lower 70s. Lows in the upper 40s to
mid 50s.
Model solutions in good agreement given the situation with the
low kicking out to the east Monday and a weak upper level trough
moving over the area Tuesday. This scenario would confine the
shower chances to the Cascades both days. Highs remaining below
normal, in the mid 60s to lower 70s. Lows in the lower to mid
50s. Felton
&&
.AVIATION...
South to southwesterly flow aloft will remain in place over W WA as
an upper level low continues to dig southward just west of the
coastline. Surface winds at the time of this writing mainly
southerly with speeds ranging 4-8 kts...give or take depending on
location. Speeds are expected to ramp up from west to east as the
front approaches...with western terminals seeing this increase by
around 12Z and interior terminals closer to 14Z or 15Z...generally
ranging 12-18 kts with gusts up to 30 kts possible. Speeds start to
ease mid to late afternoon around 22Z to 24Z down to 10-15 kts with
gusts up to 20-25 kts still possible. Speeds will remain elevated
into tonight, generally ranging 8-12 kts, but gusts will no longer
be a concern. CLM will be the exception, thanks to shadowing from
the Olympics, with winds generally light and variable with speeds
under 5 kts.
Cigs largely VFR, although MVFR conditions are present along the
coast, over some of the islands and off and on at Sea-Tac.
Increasing winds this morning should give cigs a boost...and even
with incoming rainfall most terminals should remain VFR. Exceptions
will be those that tend to favor lower cigs such as HQM, PWT and
OLM, as MVFR conditions will be present from time to time, if not
the duration of the TAF period. Rain will transition to showers by
00Z late this afternoon for most terminals, bringing a return to
widespread VFR conditions this evening into tonight.
KSEA...MVFR conditions present at the time of this writing, but as
winds increase around 12Z, should start to see conditions improve to
low-end VFR. Strongest winds still look to start up late morning,
although models put this occurring closer to 18Z than the 15Z
currently in the TAF. Will likely nudge this forward for the 12Z
issuance. Southerly winds at their peak likely to run closer to 10-
15 kts with gusts up to 30 kts possible. Speeds and gusts ease
slightly mid-afternoon running more 8-12 kts with gusts up to 20
kts. Gusts drop off after 03Z, but speeds will remain within that 8-
12 kts range. Models still suggest a slight chance (15%) of
thunderstorms in the afternoon, but with such low confidence, will
not include in forecast for now.
18
&&
.MARINE...
A low pressure system will continue its way across the region today
as its cold front moves through W WA today while the low center
moves down through the coastal waters on Thursday. Winds will be
borderline for gales, however gusts remain likely (60-90%) to reach
gale force across most of the coastal waters, and through the
northern Salish Sea from Admiralty Inlet up through the East
Entrance and into the Northern Inland Waters. Wind gusts through the
Puget Sound and Hood Canal will increase this morning, reaching
Small Craft Advisory criteria by afternoon and will continue into
possibly the early evening hours. Portions of the central Strait of
Juan de Fuca south and east of Victoria may also see Small Craft to
gale force gusts, but the majority of the zone should stay sheltered
from the strongest winds. The strongest winds area-wide should start
to decrease following the frontal passage tonight. While winds will
stay elevated over some of the interior waters, at this time it does
not look like additional headlines will be needed. Broad low
pressure will remain over region through the end of the week into
this weekend though winds look to remain light.
Chances for isolated thunderstorms will pose a threat to the area
waters today and Thursday, through probabilities remain minimal (10-
20% chc).
Seas 7-10 ft this morning increasing to 10-13 ft by noon. These
heights will not linger, as seas return to 7-9 ft late this
afternoon/early this evening and generally remaining there overnight
with possibly a slight increase to 8-10 ft. Seas ease to around 4-6
ft by Thursday night and remain like so through the weekend.
18/62
&&
.FIRE WEATHER...
Fire weather concerns remain low through the next week. A
strong for the first week of September weather system will
bring significant rainfall to the coast and Olympics through
Thursday afternoon. Rainfall amounts in the Olympics in the 1.5
to as high as 3 inch range with 1 to 1.5 inches along the
coast. Elsewhere amounts will be lower but most areas should see
a wetting rain. Rainfall may pose a minor threat to highly
sensitive and brand new burn scars. Chances for showers will
continue through the weekend with a slight chance of
thunderstorms Thursday and Friday afternoon. The risk of new
fire starts is low due to the isolated coverage and the
increased fuel moisture from the wetting rains. Even with a
drier pattern next week temperatures will remain a little below
normal keeping fire weather concerns in check. Felton
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Wind Advisory until 8 PM PDT this evening for Island County-
Lowlands of Western Whatcom County-Port Townsend Area-San
Juan County.
Wind Advisory until 5 PM PDT this afternoon for Grays Harbor
County Coast-Northern Washington Coast.
PZ...Gale Warning until 11 PM PDT this evening for Admiralty Inlet-
East Entrance U.S. Waters Strait Of Juan De Fuca-Northern
Inland Waters Including The San Juan Islands.
Small Craft Advisory until 11 PM PDT this evening for Puget
Sound and Hood Canal.
Gale Warning until 5 PM PDT this afternoon for Coastal Waters
From Cape Flattery To James Island 10 To 60 Nm-Coastal
Waters From Cape Flattery To James Island Out 10 Nm-
Coastal Waters From James Island To Point Grenville 10 To
60 Nm-Coastal Waters From James Island To Point Grenville
Out 10 Nm-Coastal Waters From Point Grenville To Cape
Shoalwater 10 To 60 Nm-Coastal Waters From Point
Grenville To Cape Shoalwater Out 10 Nm.
&&
$$
NWS SEW Office Area Forecast Discussion