902
FXUS66 KSEW 152211
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
311 PM PDT Tue Jul 15 2025
.SYNOPSIS...The dry and very warm pattern will continue through
Thursday with elevated and even critical fire weather
conditions for parts of western Washington, and widespread
moderate HeatRisk. More moderate temperatures and continued dry conditions
will return to the area Friday into the weekend.
&&
.SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/...Building upper
level high pressure and the thermally induced surface trough
moving up from Oregon have pretty quickly boosted temps this
afternoon. Temperatures already running anywhere from 10 to 25
degrees warmer than this time yesterday. The low level
northeasterly flow will continue overnight will limit overnight
cooling over much of the area. This will especially be true for
locations with even a slight easterly component to the wind
where overnight lows will remain in the low 60s. Spots near the
water or with little or now wind may manage to drop into the
upper 50s.
Wednesday remains on track for the warmest day, with warm temps
aloft and the thermally induced surface trough over the area in
the morning. Highs over the interior will reach into the upper
80s to mid 90s. For the coast, burgeoning onshore flow with the
surface trough shifting east will limit the warming there to the
70s and perhaps low 80s. The low level onshore flow Wednesday
night into Thursday is not expected to be fully developed - will
likely result in a warm - but somewhat cooler day for much of
the interior Thursday with high in the 80s. Widespread moderate
HeatRisk conditions will linger across much of Western
Washington through Wednesday with some improvement Thursday.
The heat advisory remains in effect through 10 pm Wednesday.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...Ensembles continue to
agree on the a cooling trend becoming more fully established
Friday with a more typical low level onshore flow pattern
continuing through the weekend. This will result in near- or
even below-normal temperatures. but continued dry through the
weekend. The only exception is the odd chance at light showers
over the northern Washington Cascades Sunday and again Monday
with weak upper level systems brushing the area. Highs in the
70s and lower 80s Friday lowering to the upper 60s to mid 70s
Sunday and Monday.
&&
.AVIATION...VFR conditions will prevail through the TAF period, with
the exception of KHQM. Guidance hints at IFR/LIFR conditions
returning early Wednesday morning after 7z-9z, with improvement
expected after 19z-21z. Breezy northerly surface winds this
afternoon/evening across Puget Sound terminals 10-14 kt, with gusts
around 15-20 kt possible. Winds will ease overnight and become
slightly more northeasterly. Winds will become more westerly
Wednesday morning into the afternoon.
KSEA...VFR conditions expected to prevail with mostly clear skies.
Breezy northerly winds this afternoon around 11-14 kt, with gusts up
to 20 kt possible. Winds will become more northeasterly overnight
and subside to 3-6 kt. Guidance hints at winds becoming westerly
Wednesday around 16z-19z.
29
&&
.MARINE...Surface high pressure will retreat west into the NE
Pacific with a surface trough expected to move over the waters on
Wednesday. This will bring increased wind speeds across the coastal
waters late Wednesday morning through early Thursday morning. The
strongest winds will be in the outer coastal waters, with gusts
having the potential to reach up to 30 kt. As a result, a Small
Craft Advisory has been issued. In addition to winds, seas will
build 8-11 ft for the outer coastal waters by Wednesday evening.
Moving forward, high pressure will remain over the NE Pacific and
will begin to rebuild over area waters on Friday into the weekend.
Waves will be on a decrease trend Thursday and Friday to around 6-9
ft, with waves 5 ft or below through the weekend into early next
week.
Westerly pushes across the Strait of Juan de Fuca will occur each
evening with onshore flow returning with varying degrees of
strength. The push across the Strait on Wednesday and Thursday look
to remain below advisory criteria. However, the pushes on Friday and
may meet lower-end small craft thresholds.
29
&&
.FIRE WEATHER...Widespread elevated fire weather conditions will
continue into Thursday. The Fire Weather Watch for the southwest WA
lowlands was cancelled due to no longer expecting the onshore
gradient to develop quickly enough to result in a strong push of
wind, while the relative humidities remain low. The watch for the
Cascade mountains zones 658 and 659 was upgrade to a Red Flag
Warning. Depending on the placement of the thermal trough, expect to
see a deeper mixed layer and increased instability over the Cascades
with mixing heights potentially rising into Wednesday. Wednesday
will have the worst fire weather conditions for existing incidents
and the potential for any new ones if they were to begin. Cooling
trend beginning Thursday with temperatures dropping below normal
Saturday. Minimum RH values increasing Thursday into the weekend
with the return of low level onshore flow. Felton/Bower&&
.HYDROLOGY...
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Red Flag Warning from 11 AM to 11 PM PDT Wednesday for West
Slopes of the Central Cascades Generally above 1500 Feet-
West Slopes of the North Cascades Generally above 1500
Feet.
Heat Advisory until 10 PM PDT Wednesday for City of Seattle-
Downtown Everett / Marysville Area-Eastern Kitsap County-
Eastside-Foothills and Valleys of Central King County-
Foothills and Valleys of Pierce and Southern King
Counties-Foothills and Valleys of Snohomish and Northern
King Counties-Foothills and Valleys of Thurston and Lewis
Counties-Foothills and Valleys of the North Cascades-
Lowlands of Lewis and Southern Thurston Counties-Lowlands
of Pierce and Southern King Counties-Lowlands of Western
Skagit and Northwestern Snohomish Counties-Lowlands of
Western Whatcom County-Middle Chehalis River Valley-
Northern Hood Canal-Olympia and Southern Puget Sound-
Shoreline / Lynnwood / South Everett Area-Southern Hood
Canal.
PZ...Small Craft Advisory from 11 AM Wednesday to 5 AM PDT Thursday
for Coastal Waters From Cape Flattery To James Island 10
To 60 Nm-Coastal Waters From James Island To Point
Grenville 10 To 60 Nm-Coastal Waters From Point Grenville
To Cape Shoalwater 10 To 60 Nm.
&&
$$
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