Brier Weather Station
Latitude N 47° 46' 49" Longitude W 122° 16' 48" Elevation 341 ft
823
FXUS66 KSEW 132107
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
207 PM PDT Sun Sep 13 2026
.SYNOPSIS...
The upper level low currently bringing rain to the region will
depart tonight. Cool and cloudy conditions persist into Monday,
then an shortwave trough will bring chances for showers, mainly
in the mountains, early Tuesday. Dry and warmer conditions are
expected mid-week onward as upper level ridging builds.
&&
.SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/...
A surface low pressure system, supported by an upper level low
directly overhead, will continue to move through and move east
of Washington tonight. Rain continues to fall across areas of
Seattle and southward, and east the coastline. Rain will taper
off across the interior. The bulk of the rain will end over the
mountains tonight, through chances for scattered light showers
from stronger onshore flow will continue through the overnight
period tonight. Winds will also increase this evening, with peak
gusts of around 20-30 mph across portions of the Puget Sound
lowlands, the northern interior, and the Strait of Juan de Fuca
through early Monday morning. A few breaks in the clouds may be
possible this evening before convergence zone and marine layer
clouds fill in tonight into Monday morning. Monday will see a
slow break up of the clouds through Monday evening with mostly
dry conditions. Highs today and Monday in the mid to upper 60s,
with lows in the upper 40s to mid 50s.
Following the departure of the upper level low on Monday, dry
northwesterly flow will persist on Monday, through this will
drag a shortwave trough down along the British Columbia coast
and move across western Washington early on Tuesday. Most
locations will just see an increase in clouds again Tuesday
morning, though there will be slight chances for some isolated
showers, mainly in the mountains, on Tuesday morning. Clouds
will begin to clear late Tuesday. Temperatures will remain mild,
with highs in the mid 60s to near 70. Lows in the mid 40s to low
50s.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
The trough will continue to sink southward on Wednesday and
still over the OR/CA border, with upper level ridging nosing
over western Washington. This should be enough to develop a
weak surface thermal trough along the coast, allowing the low
level flow to turn offshore. This will help to promote warmer
and dry conditions through the end of the week. Highs, beginning
Wednesday, will rise into the mid 70s to low 80s in the warmest
locations. This should last through the at least the end of the
week. Models are hinting that the pattern should progress next
weekend, but is uncertainty as to how quickly the low to the
south will exit and allow the ridge to progress east as well.
62
&&
.AVIATION...
Upper level low will shift N/NE with rain tapering
off across western WA this afternoon and early evening. Until
then, low clouds, light rain, and MVFR conditions will continue
in the interior with VFR conditions at the coast. Widespread
MVFR conditions will return overnight into Monday. Gusty winds
to 20-25kt expected in the interior 00-12z with increasing
onshore flow. 33
KSEA...Light rain diminishing this afternoon but still seeing
plenty of low clouds and MVFR conditions. A brief window of VFR
is possible between 00-06z, then MVFR conditions returning
through Monday morning. Gusty S/SW winds to 20-25kt expected
from 00-09z. 33
&&
.MARINE...
Increasing onshore flow tonight with Small Craft
Advisory winds over Puget Sound/Hood Canal, Northern Inland
Waters and the Strait of Juan de Fuca. Winds will ease early
Monday morning. Weak onshore flow on Monday with the flow
turning more northerly on Tuesday. Offshore flow will develop
Wednesday and Thursday as a thermal trough forms along the
coast. Onshore flow will return Friday and into the weekend. 33
&&
.FIRE WEATHER...
Fire weather concerns remain minimal through the next week.
Rains from today will increase fuel moisture across at least the
southern half of the region. The pattern turns drier and warmer
mid to late week, with the surface winds going light onshore.
Daytime minimum relative humidity look to drop below 30%, which
will allow more reactive fuels to start to dry out.
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory from 6 PM this evening to 5 AM PDT Monday
for Central U.S. Waters Strait Of Juan De Fuca-East
Entrance U.S. Waters Strait Of Juan De Fuca-Northern
Inland Waters Including The San Juan Islands-Puget Sound
and Hood Canal.
&&
$$
NWS SEW Office Area Forecast Discussion