Heat in Washington, August 31, 2022

Area Forecast Discussion
National Weather Service Seattle WA
756 PM PDT Tue Aug 30 2022

.SYNOPSIS...Strong high pressure remains over the area into
Wednesday, maintaining well above normal temperatures across the
interior. A weak disturbance brings briefly cooler temperatures
Thursday, followed by stronger system Saturday. The region then
likely remains in between high pressure centered to the east and
low pressure to the northwest through the early part of next week.

&&

.UPDATE...The main focus this evening has been a deep dive into
the temperature forecast through Friday. A number of high
temperature records were broken today, including Hoqiuam hitting
the 88 degree mark, warmer than many areas further inland. Highs
Wednesday are expected to be near to slightly below those seen
today, though areas along the Washington Coast should be
considerably cooler. A very minor cool down is expected Thursday
with some morning cloud cover but temperatures are looking
increasingly likely to rebound back up Friday. The latest cluster
analysis is putting about an 80 percent chance that 850mb
temperatures will be at or above 20C Friday, with a significant
grouping at 22 to 24 degrees which would roughly equate to
surface temperatures in the upper 80s to around 90 once again for
the interior lowlands. As a result, confidence is high enough to
have a Heat Advisory in effect for Friday. With only a minor cool
down expected Thursday, went ahead an simply extended the Heat
Advisory for most locations all the way through Friday, rather
than leave a gap with limited relief. Also added the East Puget
Sound Lowlands to the Advisory.

Also monitoring smoke orginiating from fires in the North
Cascades. The predominent flow should keep the bulk of this smoke
moving north/east for the time being.
-Wolcott-

&&

.SHORT TERM /TONIGHT THROUGH FRIDAY/...High pressure continues to
build over the region today, with generally clear skies across
Western Washington as only a few mid-level clouds are moving
through. Temperatures climbing through the 80s through the
interior already this afternoon, with the areas immediately along
the water holding slightly cooler. Expect modest cooling
overnight as some marine air does seep into the interior, but any
clouds or fog should generally remain confined mostly to the
immediate coast (perhaps as far inland as Hoquiam and Aberdeen)
and coastal waters as a modest flow reversal brings southerly
winds and some fog pushing north from the Oregon waters.
Meanwhile, some haze may be evident across portions of the area
next few days as smoke from fires may drift overhead, but this
should generally remain elevated as is does so.

For Wednesday, another warm day on tap across the interior, but a
passing shortwave could provide just enough lift to tap into some
elevated moisture and bring some cumulus buildups and even a few
isolated thunderstorms immediately along the Cascades near the
crest. The chances are highest, about 10-15%, in the North
Cascades in the afternoon. Meanwhile a deeper marine push late
Wednesday night should bring a return of stratus into the interior
by daybreak Thursday. Can't rule out some light drizzle near the
coast, but impacts should be rather limited. With some more
morning cloud cover, expect temperatures to be just a few degrees
cooler Thursday than Wednesday for most, but otherwise another
above normal and generally sunny afternoon. Not much change to the
pattern into Friday and will less in the way of morning clouds and
the heights rebounding, expect that temperatures will warm a few
degrees, or similar to Wednesday's temperatures for most of the
area. Ensembles then in good agreement that the ridge advances
eastward with the next upper trough moving into the area late
Friday night, bringing another deeper onshore push and a more
significant cooldown into the weekend.

.LONG TERM /SATURDAY THROUGH TUESDAY/...As mentioned, the next
upper trough is then expected to slide across the region by early
Saturday, ushering a deeper marine push and a cooler day. While
chances for rain remain low, some light showers may develop along
the coast, Olympic Peninsula, and across the northwestern portions
of the region through the day. Meanwhile, temperatures Sunday
likely rebound to a few degrees above normal as the heights again
rise. Confidence in the remainder of the start of next week is a
little bit lower with general agreement in a ridge centered to
the east near the Great Basin and a trough upstream near the Gulf
of Alaska, with the region somewhere in the middle. Roughly half
of ensemble members keep the ridge more dominant and temperatures
somewhat above normal, while the other half reflect some influence
from the trough - for now, the forecast continues to reflect a
middle ground close to an ensemble mean with temperatures near
normal for Monday and Tuesday.

&&

ZCZC SEAWRKAFD 310233
TTAA00 KSEA DDHHMM

.AVIATION...An upper level ridge will continue to influence the area
through Wednesday. VFR conditions can be expected at all terminals
through the next 24 hours, with the exception of HQM where coastal
marine stratus will blanket the terminal with an IFR/LIFR ceiling
after midnight. A weak weather system will pass through Wednesday
afternoon/evening and dampen the ridge temporarily. It may provide
enough energy for isolated thunderstorm or towering cu development
over the Cascades but is not expected to pose any threats to the
terminals. Winds N this evening 5-10kts, becoming more light and
variable overnight and SW again 7-10kts Wednesday afternoon, with a
few gusts 15-20 kts possible.

KSEA...VFR. Winds N this evening around 10kts will ease overnight
and become more variable at or below 5kts. Winds W/SW Wednesday
afternoon around 10kts with a few isolated gusts around 15-20kts.

Kovacik

&&

.MARINE...Marine forecast is unchanged this evening. Observations
show winds below SCA over the Inner Coastal Waters where the
advisory remains in place. Will leave in effect thru 11 PM for the
potential for spotty winds around 21kts over the open water. Winds
will ease overnight, with a decent westerly push down the Strait
Wednesday evening as a shortwave trough lifts across the area.
Previous discussion below:

Small Craft Advisory winds for the south part of the
inner Coastal Waters will ease later tonight. The thermal trough
along the coast will start to shift inland on later tonight into
Wednesday, providing increased onshore flow.

With the abundance of onshore flow, west wind pushes for the
Central and Eastern Strait are likely Wednesday evening and Friday
evening, prompting a set of SCA headlines. The winds on Wednesday
look to be stronger than Fridays push down the Strait, with winds
briefly touching gale force in the strait.

Kovacik/Mazurkiewicz

&&

.HYDROLOGY...The daily hydrology discussion has ended until the
start of the next rainy season; it will only be updated as needed.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Heat Advisory until 9 PM PDT Friday for Bellevue and Vicinity-
     Bremerton and Vicinity-East Puget Sound Lowlands-Everett
     and Vicinity-Hood Canal Area-Seattle and Vicinity-Southwest
     Interior-Tacoma Area.

PZ...Small Craft Advisory until 11 PM PDT this evening for Coastal
     Waters From James Island To Point Grenville Out 10 Nm-
     Coastal Waters From Point Grenville To Cape Shoalwater Out
     10 Nm.

&&