Brier Weather Station
Latitude N 47° 46' 49" Longitude W 122° 16' 48" Elevation 341 ft
831
FXUS66 KSEW 170919 CCA
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
212 AM PDT Fri Jul 17 2026
.SYNOPSIS...Conditions are favored to trend drier over the
weekend with near-seasonal temperatures. High pressure then
builds over the area next week, bringing continued dry weather
and well-above average temperatures along with Moderate
HeatRisk.
&&
.SHORT TERM /TODAY THROUGH SUNDAY/...
Latest satellite imagery shows an abundance of low level clouds over
W WA this morning thanks to plenty of moisture from Thursday`s
rains. The upper level low responsible for such is easily seen just
off the NWern WA coast, although its movement to the northeast is
not quite what models had been advertising. Regardless, new
development of thunderstorms over E WA this early morning shows that
at least for now, W WA seems to no longer be under any direct
influence from this system.
Low chances for lingering showers remain possible this morning and
afternoon over the northernmost portions of the Olympic Peninsula,
otherwise, dry conditions expected to resume today. Following the
trend established 24 hours ago, models seem to be slowing down the
ramping up of temperatures in favor of a slower warming
trend...which makes sense given that the upper level trough
associated with the aforementioned low will linger for at least the
first half of the weekend. As such, highs today will only see a few
degrees of warming...into the lower to mid 70s for the interior and
mid 60s along the coast. Saturday continues this incremental
increase with highs generally in the mid 70s /still mid 60s for the
coast/ and Sunday warms up to the mid 70s to near 80 as the coast
finally starts to see some movement upward, generally in the mid to
upper 60s. As such, this will keep HeatRisk down in Minor/Yellow
throughout the short term period.
18
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
Upper level ridging over the eastern Pacific starts to move into W
WA Sunday evening, and by the time this feature gets its axis along
the coast Monday, it will fuel a steep warm-up to temperatures as
much as 10 degrees above climatology for this time of year. Highs
Monday ranging generally in the mid 80s to near 90 while the coast
sees temps in the lower to mid 70s. Ridging over the Four Corners
region ends up getting drawn northward for the first half of next
week, keeping conditions hot and dry. Highs Tuesday look to be the
warmest of the period with inland temperatures in the upper 80s to
lower 90s. Temps cool very slightly, a degree or two at best, with
daytime highs both Wednesday and Thursday ranging in the mid to
upper 80s. All that said, it should not come as any surprise that
this will also push HeatRisk higher with widespread Moderate/Orange
conditions for the interior lowlands each day of the long term
period. Tuesday and Wednesday are also showing isolated patches of
High/Red...which will need to be monitored should temps trend any
higher for possible heat related headlines.
18
&&
.AVIATION...
An upper level low centered just west of Cape Flattery
early this morning will gradually lift northward into British
Columbia today with southerly flow aloft becoming southwesterly
tonight. The low level flow is light onshore. Widespread low level
moisture west of the Cascade crest will produce mostly MVFR ceilings
through around 18Z before gradually lifting and scattering for most
areas this afternoon. Ceilings may linger into mid-afternoon along
the coast. Low MVFR or IFR ceilings are expected to redevelop along
the coast tonight. Confidence in areal coverage of low ceilings for
interior areas Saturday morning, especially east of Puget Sound, is
low at this time.
KSEA...MVFR ceilings are expected to persist through around 18Z
before lifting and scattering out this afternoon. There`s around a
50% chance or so of MVFR ceilings for a period between 11Z and 17Z
on Saturday. Surface winds southerly 6 knots or less will veer to
the west/northwest by around 00Z then light north/northwesterly late
this evening.
27
&&
.MARINE...
Weak surface low pressure over the coastal waters today
will dissipate on Saturday as a broad surface ridge centered well
offshore expands eastward. This will lead to varying degrees of
onshore flow into the middle portion of the coming week. Thermally
induced surface low pressure is expected to expand across the
interior of Western Washington Monday through Wednesday. As a
result, diurnally driven westerly pushes in the strait can be
expected as well as occasionally gusty northwesterlies over the
outer coastal waters with both areas reaching small craft advisory
strength at times.
27
&&
.FIRE WEATHER...
Fire weather concerns will linger throughout the forecast period as
a hotter and drier pattern returns quickly over Western Washington,
especially into early next week. This has the potential for
increasing fire activity from any new lightning starts from
Thursday`s convection.
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...None.
&&
$$
NWS SEW Office Area Forecast Discussion