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104
FXUS66 KPQR 281828
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
1123 AM PDT Fri Jun 28 2024


.SYNOPSIS...
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Aside from some light drizzle across the northern
portions of the CWA late Saturday into Sunday, onshore flow will
maintain near average temperatures into early next week. There is
30-40% chance that stronger high pressure offshore will shift over
the region towards the end of next week and bring our hottest
temperatures of the Summer so far.
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&&


.SHORT TERM...
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Friday through Sunday...Dry weather has returned
to NW Oregon and SW Washington as fairly zonal upper level flow
takes shape over the region into tomorrow. Winds aloft and at
the surface have shifted northerly and will remain in this
light offshore pattern today. Daytime temperatures will warm
nearly 10 degrees inland from yesterday`s temperatures under
sunny skies and with the warming north winds. Expect 60s along
the coast and upper 70s to low 80s across the inland valleys.
NBM indicates a 60-70% probability of temperatures exceeding 80
degrees for the Willamette Valley and a 15-30% for reaching 85
degrees.

Saturday remains warm with temperatures rising a couple
degrees. NBM probabilities for exceeding 80 degrees and 85
degrees in the Willamette Valley increase to 70-80% and 35-50%
respectively. Temperatures along the coast will remain fairly
steady in the 60s as winds will turn more westerly from a broad
trough deepening into the eastern Pacific and approaching the
region. Clouds will begin spreading over the region through the
day, which could potentially keep temperatures from rising as
much as expected depending on how thick the cloud cover is.

The upper trough moves inland Sunday, though ensemble guidance
continues weakening the forcing and shower chances. Latest
guidance indicates only a 10-25% chance of showers for the
northern Cascades and Coast Range due to orographic forcing,
though some drizzle is possible along the coast. Any
accumulation will be very limited. Temperatures will fall a few
degrees back to near normal with upper 70s in the inland valleys
and upper 50s to 60s along the coast. -HEC


.LONG TERM...Monday through Friday...As the trough passes to
the east on Monday, WPC clusters are in very good agreement of
upper ridging building over the Eastern Pacific Monday into
Wednesday with mostly zonal flow continuing over the PacNW.
This is expected to keep temperatures pretty steady with 60s
along the coast and upper 70s to low 80s inland. Beyond
Wednesday, uncertainty remains on whether the ridging will
spread east inland or remain out over the ocean. Nearly all
clusters show the ridging moving east at some point into
Friday, but strength of the ridge as well as timing varies
drastically. As such, NBM high temperature spreads for inland
areas range anywhere from around 80 degrees for the 25th
percentile to the low 90s for the 75th percentile for the 4th of
July holiday and the following Friday. Current deterministic
NBM forecast hedges temperatures to the upper 80s which. -HEC
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&&


.AVIATION...
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High pressure offshore and thermally induced
lower pressure over the Great Basin and California will lead to
mainly VFR conditions and typical diurnally driven northwest to
northerly winds through 18z Saturday. The main exception to this
will be along the north coast where there is a 30-40% chance of
MVFR ceilings at any given hour at KAST between 12-18z Saturday.

PDX AND APPROACHES...High pressure offshore and thermally induced
lower pressure over the Great Basin and California will lead to
mainly VFR conditions and typical diurnally driven northwest to
northerly winds through 18z Saturday. /Neuman
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&&


.MARINE...
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Weak high pressure over the northeast Pacific with lower
surface pressure over California and the Great Basin will more or
less maintain itself into next week. A weak front will temporarily
try to clip the waters tonight into Saturday and turn winds more
out of the west. Otherwise, expect north to northwest winds
across the waters with the strongest winds generally off the
central coast of Oregon and lighter winds farther north. Winds
will generally peak in the afternoon and evening hours each day.
Pressure gradients appear increasingly likely to increase by early
to mid next week so that there is a >90% chance that northerly
wind gusts of 25-30 kt spread northward across the waters. This
will in return develop steep wind driven seas of 5-8 ft with a
dominant period of 7-8 seconds by Tuesday or Wednesday. /Neuman
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&&


.PQR WATCHES/WARNINGS/ADVISORIES...

OR...None.
WA...None.
PZ...None.

&&


$$

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