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840
FXUS66 KPQR 101028 CCA
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
325 AM PDT Mon Jun 10 2024

.SYNOPSIS...High pressure will lead to warm, dry, and sunny
conditions today. Another weak system may clip the north Oregon
and south Washington coast with drizzle or light rain Tuesday.
Then high pressure returns, bringing warmer and drier weather
Wednesday and Thursday. Temperatures may dip below normal going
into the weekend as most forecast models bring an upper trough
onshore - potentially strong enough to bring more widespread
rain to the region.

&&

.SHORT TERM...Today through Wednesday...Satellite imagery as of
3 AM PDT depicts a marine layer along the coast along with low
stratus backbuilding against the Cascades near the Portland
Metro Area. Other than these low stratus clouds, not much going
on in terms of weather today. A high pressure ridge will build
aloft today, bringing mostly sunny skies and warm conditions.
Model soundings suggest that the marine layer along the coast
will break up and give way to more sunshine by late morning.
With HREF/LREF 850mb temperatures between 12-15 deg C today,
most interior lowlands should climb into the low 80s. Meanwhile,
coastal locations will remain more mild with highs in the 60s.
A greater northerly component to low-level wind will also lead
to drier conditions today.

The NE Pacific remains more active than usual for June,
and this will continue to be the case Monday night/early
tomorrow (Tuesday) morning as another upper trough moves into
British Columbia, pushing the tail end of its cold front into
the Pacific Northwest. In this scenario, north coastal zones
may get brushed with some drizzle or light rain. PoPs remain low
(15-35%), with the highest PoPs along the south Washington
coast and Willapa Hills where guidance has a some QPF early
tomorrow morning.

High pressure quickly returns tomorrow afternoon, drying things
out. High temps tomorrow afternoon will be a few degrees cooler
inland than today, but still remain warm in the mid to upper
70s. NBM only suggests a 15-30% chance of exceeding 80 degrees
in the Willamette Valley tomorrow. Going into Wednesday, we
maintain warm and dry conditions as high pressure remains over
our area.        -Alviz/Weagle

&&

.LONG TERM...Thursday through Sunday...By Thursday, ensemble
members agree on shortwave ridging over the region, supporting
drier and warmer conditions. Friday, the upper ridge begins to
shift eastward as another trough near the Gulf of Alaska dips
southward toward the Pacific Northwest. This will lead to a
cooling trend and return of widespread low PoPs. Saturday, most
ensemble members agree on troughing entering the region with
below-average 500 mb heights. If this scenario pans out, then we
would see increasing chances for widespread precipitation and
potentially below average temperatures. For now, the NBM`s
15-45% chance of PoPs across northwest Oregon and southwest
Washington at the end of the week look reasonable. Sunday, most
ensemble members (85%) continue to show troughing, but are uncertain
of the exact axis location and magnitude. Meanwhile, the other
15% of members show ridging returning over us, which would lead
to a warm-up.      -Alviz

&&

.AVIATION...Onshore flow through the next 24 hours. Dry at the
surface, but aloft around 1500-2500 ft, atmosphere is saturated -
especially along the coast. Morning marine stratus will partially
clear through the afternoon before redeveloping overnight after
07Z Monday. This marine stratus is advecting down the Columbia
River impacting terminals around KKLS. Satellite shows this
stratus filling in around KPDX and KTTD as well this afternoon.
Going to keep an eye out through the Willamette Valley for more
MVFR stratus forming. However, models are not handling this system
very well this morning.

High pressure will increase through the day today leading to
widespread VFR conditions and winds less than 10 kt. Along the
coast, some terminals may see gusts as high as 20 kt, but
generally only if the winds are between 340-360 degrees.
Overnight, another very weak front will move over the area. Will
saturate with higher chances (around 65%) for IFR stratus from
KTMK southward. Inland sites will stay VFR, but will still see
cloud cover.

PDX AND APPROACHES...Generally VFR with a period of low-end MVFR
CIGs between 10-16Z Monday. Northwesterly flow through the day.
While stratus will reform over night, there is less than a 10%
chance for MVFR CIGs after 08Z Tuesday. -Muessle


&&

.MARINE...Buoys continue to show winds around 10-15 kt with gusts
up to 20 kt, with some isolated gusts to 21 kt around 46050.
Because these gusts are not frequent, have decided to let the
Small Craft Advisory lapse. Seas are around 5-8 ft at 12 seconds,
with the highest seas in the southcentral waters which coincides
with the higher wind speeds. High pressure will keep conditions
stable through the day.

On Tuesday, a weak cool front will pass over the waters but will
likely not be impactful as it is decaying as it reaches the shore.
Northerly winds will increase once again Tuesday night into
Wednesday as another area of high pressure redevelops over the
waters. With this slight pattern shift, Small Craft Advisory winds
and associated combined seas will occur. Through the afternoon,
winds will increase even further with gusts up to 30 kt possible,
with the higher probabilities along the inner waters. -Muessle

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

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

&&$$

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