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846
FXUS66 KPQR 200314 AAA
AFDPQR

Area Forecast Discussion UPDATED National Weather Service Portland
OR 813 PM PDT Wed Jun 19 2024

...EVENING UPDATE, for aviation weather.

.SYNOPSIS...Much warmer through the remainder of the week under
building high pressure, with moderate heat risk expected from
Portland to Salem Thursday through Saturday. More seasonable
temperatures return Sunday into early next week.

&&

.DISCUSSION...
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Today, clear skies across northwest Oregon and
southwest Washington as northerly flow continues to advect drier air
into the region. Expect above normal temperatures to last through
the end of the week as high pressure builds and a surface thermal
trough continues to strengthen from the California Central Valley
into south-central Oregon. This will induce easterly flow over the
Cascades and downsloping into the interior lowlands, increasing
highs well into the 80s this afternoon.

Heat looks to peak Thursday into Friday as 500 mb heights continue
to gradually rise and 850 mb temps increase to around 15-17 C. NBM
and ensemble guidance continue to depict temperatures ending up
right around 90 degrees both Thursday and Friday afternoon from the
Portland metro down to Salem. As for the south Willamette Valley and
the I-5 corridor in southwest Washington, highs will be around the
mid to upper 80s Thursday and Friday. The chance to reach 95 degrees
on Friday is around 20-40% in the Portland and Salem areas, with
chances around 5 percent in the Eugene area. These probabilities
improve confidence in the temperature forecast for the end of the
week as highs around 90 support a moderate HeatRisk for the Portland
and Eugene areas. Overnight lows will drop into the mid to upper
50s, offering enough overnight recovery to help mitigate more
widespread or cumulative HeatRisk concerns.

Into the weekend, temperatures may remain a bit warmer on Saturday
as models suggest a delay in strong onshore flow as high pressure
shifts east of the region. This is reflected by NBM probabilities
(40%) of reaching 90 degrees on Saturday for the Portland and Salem
areas. More pronounced cooling will still arrive by Sunday as WPC
ensemble clusters continue to depict the next trough approaching the
Pacific Northwest, dropping temperatures back near seasonal normals
in the mid 70s. These temperatures will persist through the early
part of next week as the region remains under the influence of the
trough. Models have started to trend drier with the forecast as the
core of the upper low remains well to the north over British
Columbia, with any low end precipitation chances towards the end of
the period now generally confined to the far north Oregon Coast and
southwest Washington. -JH/CB
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&&

.AVIATION...
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No major changes. High pressure remains over the region,
with dry westerly flow  aloft. This will maintain VFR with variable
thin high clouds at times. Bit of onshore flow will maintain areas
of IFR stratus and patchy fog along the coast this evening. Will see
stratus break up and clear along the Washington coast towards
midnight, with that clearing gradually working its way southward to
KAST by 09Z, and then to KONP around 18Z.

PDX AND APPROACHES...No weather impacts expected, as high pressure
maintains VFR with mostly clear skies into Thu.
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&&

.MARINE...Not much change as high pressure offshore is expected
to persist through the week. Northerly winds around 15-20 kt will
continue today. Expect periods of winds gusting up to 25 kt through
Friday during the late afternoon and evenings. Gusty winds will
relax after 11 PM for a brief period but will increase back up to 25
kt for the outer waters. The inner waters may see a few gusts around
20 kt but not expecting widespread so the Small Craft has not been
extending for the inner waters. Seas around 4 to 6 feet will
generally be wind driven through the week. A weak front is expected
to approach the waters this weekend. -Batz/DH

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

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OR...None.
WA...None.
PZ...Small Craft Advisory until 11 PM PDT this evening for
PZZ251>253.

     Small Craft Advisory until 8 PM PDT Thursday for PZZ271>273.
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&&

$$

www.weather.gov/portland

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