829
FXUS66 KSEW 040248
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
748 PM PDT Wed Jul 3 2024

.UPDATE...The forecast remains on track with temperatures across
western Washington largely in the 70s, in the 60s adjacent to the
coasts. One more cool night tonight with lows in the low to mid
50s before the ridge begins to move in and build. The previous
discussion follows, including updates to aviation and fire
weather.

LH

&&

.SYNOPSIS...Dry conditions and warming temperatures are expected
through Sunday. Hot conditions are expected Friday through at
least Monday across much of the region. These conditions will also
result in elevated fire weather concerns through the weekend into
early next week. While slight cooling is expected next week,
temperatures will remain well above normal throughout most of the
week.

&&

.SHORT TERM /TONIGHT THROUGH SUNDAY/...A ridge of high pressure
will continue to shift east across the eastern Pacific through
Friday before stalling along the west coast and amplifying this
weekend. This will result in a steady warming trend from pleasant
conditions today to hot conditions by Friday into the weekend.

For the Independence Day holiday, expect temperatures in the
upper 70s to mid-80s across the lowland locations away from the
coast. Winds will be out of the north at 10-15 mph, highest along
the coast and through the Puget Sound.

By Friday, daytime highs will rise well into the 80s or even low
90s across the interior. This will result in widespread HeatRisk
levels reaching moderate/orange across the region. Several more
degrees of warming are expected Saturday as the ridge strengthens
allowing HeatRisk levels to reach major/red in favored areas such
as urban heat islands and the eastern slopes of the Cascades and
Olympics. While areas along the immediate coast of Washington may
see temperatures peak on Saturday, most areas will likely see
temperatures peak on Sunday. On Sunday expect widespread high
temperatures in the upper 80s and 90s area-wide. Highs around 100
degrees cannot be ruled out across the southwestern portions of
the CWA. A Heat Advisory was issued this morning, beginning at
noon on Friday and extending through the weekend for all areas.
The Heat Advisory will continue through Monday for areas away from
the Washington Coast.


.LONG TERM /MONDAY THROUGH THURSDAY/...Weak onshore flow will
result in a slight decrease in temperatures Monday, though
widespread temperatures in the upper 80s to low 90s are still
expected. This will be the beginning of a very slow ramp down in
temperatures next week. Even though temperatures will be on a
downward trend, they will still be several degrees above normal
throughout the week. It is possible that the Heat Advisory
currently in effect may need to be extended beyond Monday for
some areas. At this time there is no signal for precipitation
through the next 7-10 days and as such fire weather concerns will
continue to escalate for the foreseeable future. See the fire
weather section for additional details.
-Wolcott-

&&

.AVIATION...Northwesterly flow aloft as an upper level ridge
continues to build over the area. High pressure resulting in
offshore surface flow will result in dry and stable conditions
tonight and Thursday. VFR conditions in place and will remain that
way for the TAF period. Coastal locations could see some marine
stratus that could allow for MVFR to IFR cigs overnight through
Thursday morning before VFR conditions resume there.

KSEA...Clear skies with north winds with speeds generally 5 to 10
kts through the TAF period. Speeds will increase to 10-15 kt
Thursday from 21-03z.

33/18

&&

.MARINE...Flow turning offshore tonight and Thursday while a
thermal trough forms along the coast. Winds are generally light
over the waters. Offshore flow will prevail over the weekend with
the winds flipping back to onshore Sunday night and Monday.

33/18

&&

.FIRE WEATHER...Benign fire weather conditions are expected to
remain through Thursday. However, confidence is high on an
amplifying upper-level ridge settling over the region beginning
Friday. Not only will dry conditions persist, but hot weather is in
the forecast thanks to easterly flow created by a developing thermal
pressure trough along the coast. The heat is expected to peak over
the weekend with the hottest temperatures likely on Sunday. Critical
RH values are trending widespread over the Cascades with isolated
areas within the Olympic Mountain valleys during this time. The hot
and dry setting will be enough to maintain elevated fire weather
conditions especially with fuels expected to dry out rapidly during
this heat stretch. The next notable push of onshore flow will arrive
Sunday night into Monday. It`ll bring decent RH recoveries to fire
zones such as 650 but won`t be strong to completely limit the threat
for the Cascades early next week.

McMillian/18

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Heat Advisory from noon Friday to 10 PM PDT Monday for Admiralty
     Inlet Area-Bellevue and Vicinity-Bremerton and Vicinity-
     East Puget Sound Lowlands-Eastern Strait of Juan de Fuca-
     Everett and Vicinity-Hood Canal Area-Lower Chehalis Valley
     Area-Olympics-San Juan County-Seattle and Vicinity-
     Southwest Interior-Tacoma Area-West Slopes North Cascades
     and Passes-West Slopes North Central Cascades and Passes-
     West Slopes South Central Cascades and Passes-Western
     Skagit County-Western Whatcom County.

     Heat Advisory from noon Friday to 10 PM PDT Sunday for Central
     Coast-North Coast-Western Strait of Juan De Fuca.

PZ...None.
&&

$$