315
FXUS66 KPQR 061009
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
309 AM PDT Thu Jun 6 2024

.SYNOPSIS...High pressure will maintain mostly clear skies and
warm conditions through the weekend. The warmest day will be
tomorrow (Friday), with afternoon highs well above-normal.
Recent rain may make things feel a bit more humid. Expect
increasing cloud cover Saturday-Sunday with a weak trough, but
no precipitation expected. Above-normal temperatures continue
into the long term forecast, but uncertainty remains with how
strong high pressure will be.

&&

.SHORT TERM...Today through Saturday...High pressure will
persist over the Pacific Northwest through the end of the week,
maintaining dry and warm conditions. Expect sunny skies today,
with afternoon highs in the low 80s for interior valleys and 60s
to 70s for higher terrain. We`ll maintain onshore (northwest) flow,
so afternoon sea breezes will support temperatures in the 60s
along the coast.

The upper level ridge will reach it`s maximum amplitude
tomorrow (Friday), likely bringing the warmest temperatures of
the week. Friday afternoon highs for inland locations are
expected to be 15-20 degrees above normal, with temps forecast
in the upper 80s. The latest NBM guidance suggests that there
is a 30-50% chance of afternoon temperatures exceeding 90
degrees from Salem to the Portland Metro Area, the Columbia
River Gorge, and Upper Hood River Valley. These locations will
have a moderate heat risk - this level of heat affects most
individuals sensitive to heat, especially those without
effective cooling and/or adequate hydration. Also considering
the recent rain, we could feel a bit more humidity in the warm
air.

Friday night, the upper level ridge begins to move eastward as a
weak shortwave trough approaches the Pacific Northwest. This
will bring more southwesterly flow aloft as well as increasing
mid to high level cloud cover late Friday night into Saturday.
Since our air mass will be so dry when this shortwave moves in,
it`s unlikely that we`ll see any precipitation or thunderstorm
activity. As a result, did reduce NBM PoPs to below 25% in the
Cascades Saturday afternoon and Saturday night. If any showers
or thunderstorms did form, the westerly component to the flow
aloft would likely carry it east of the Cascade crest. Otherwise,
we could see virga at best.

High temps on Saturday will likely begin to cool with increasing
cloud cover, but still remain above normal inland. 500 mb
heights remain above-normal, representing the warm air mass in
place. In addition, ensemble guidance still show 850 mb temps
around 14 deg C, which would support high temps reaching the
low 80s for interior valleys. NBM guidance suggests a 50-70%
chance that locations in the Willamette Valley exceeds 80
degrees on Saturday.      -Alviz

&&

.LONG TERM...Saturday night through Wednesday...The upper level
shortwave trough will push through the region and weaken
Saturday night to Sunday. Still expect mostly dry conditions as
our air mass will be too dry to support precipitation. Sunday
morning could start off with some cloud cover, but clouds would
dissipate by the afternoon as high pressure re-builds behind
the shortwave.

Most WPC clusters are in general agreement of maintaining high
pressure with above-normal 500 mb heights over the Pacific
Northwest through mid next week. However, the clusters still
differ on the precise magnitude and placement of the ridging.
The most uncertainty comes Tuesday-Wednesday, when ensemble
guidance shows an upper trough near the Gulf of Alaska pushing
into British Columbia. Depending on how far south this trough
ends up, this would influence the strength of high pressure
over us and thus how warm we end up getting.

Temperatures are expected to remain above normal through the
long term period, but with a wider range of outcomes. NBM
probabilistic guidance which shows a 10-15% chance of reaching
90 degrees and less than a 5 percent chance to reach 95 degrees
throughout the Willamette Valley next Tuesday. However, the 25th
percentile solution would result in temperatures in the mid to
upper 70s on Tuesday and Wednesday. Generally speaking, the
pattern favors a continuation of warm and dry weather through
the extended, but with less confidence on where high
temperatures will ultimately land.        -Alviz

&&
.AVIATION...High pressure lingers over the region with VFR
conditions through the next 24 hours. Some areas along the coast
are seeing patchy marine fog which is reducing VIS to MVFR levels.
However this will be short lived and will improve with the
daytime heating. Winds will be generally north to northwesterly.
Areas along the coast, and from KSLE southward to K77S within the
Willamette Valley will see slightly stronger winds - especially
after 06Z Friday. Around KEUG, there is a 10% chance that gusts
could reach as high as 30 kt but trending towards more of a 20 kt
gust forecast. Around 5000 ft ASL, wind speeds will be high
initially this morning (around 35 kt), then will ease through the
afternoon to around 20 kt from the northwest.

PDX AND APPROACHES...VFR with no concerns. Mainly wind driven
forecast changes, but in general northerly winds through the day
with a 10% chance of gusts up to 25 mph after 06Z Friday.
-Muessle

&&

.MARINE...High pressure over the region will lead to clear skies
and fairly persistent winds. Will see a northerly wind through
the next few days which will ramp up around 5 PM Thursday. From
PZZ272/252 southward, gusts could reach speeds up to 30 kt. This
is generally due to heating changes through the day. Seas will
hover right around 10 ft at 13 seconds. Have extended the small
craft advisory for the northern waters as seas have remained
elevated and winds will ramp up again in several hours.

Conditions will begin to ease on Saturday as a very weak front
nears the waters. This front appears to have limited impact, but
cannot rule out some gustier conditions here or there. Seas will
lower to around 5 to 7 ft at 12 seconds. -Muessle

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...None.
WA...None.
PZ...Small Craft Advisory until 8 AM PDT this morning for PZZ210.

     Small Craft Advisory until 11 PM PDT this evening for PZZ251-271.

     Small Craft Advisory until 6 AM PDT Friday for PZZ252-253-272-
     273.
&&


$$

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