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000
FXUS66 KPQR 182131
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
231 PM PDT Thu Apr 18 2024

.SYNOPSIS...
High pressure over the region will remain through
Friday, maintaining mild sunny days and cool clear nights.
Offshore flow continues, with breezy easterly winds on the west
slopes of the Cascades and to some degree, the Coast Range.
Will return to cooler conditions this weekend, as a front pushes
across the region. Unsettled weather continues into early next
week.

&&

.SHORT TERM...TODAY THROUGH SATURDAY...High pressure continues
in the region, with sunny and warm conditions. Temperatures
today are on track to reach right about to 70 or just barely
into the low 70s throughout the Willamette Valley, while the
coast will be just a bit cooler, peaking in the upper 60s.
Offshore flow continues, with generally NE winds curling N in
the central and southern Willamette Valley. Generally pleasant
spring conditions expected today and tomorrow.

Breezy east winds through the Gorge are currently gusting to
around 25mph, but this is expected to continue increasing
through tonight and Friday as the thermal trough continues
building. High temperatures Friday will be just a degree or two
warmer, and east wind through the Gorge will increase late
Thursday night/early Friday morning. Exposed upper elevation
areas could see gusts potentially up to 35-50mph throughout most
of Friday, gradually weakening over Friday night. The rest of
the region should see NE or E breezy winds up to 10-20 mph. Will see
wind-reversal along the coast in the afternoon, with east to
northeast winds becoming southerly to south of Florence in the
afternoon, and as far north as Newport by sunset as the thermal
trough shifts inland over the Coast Range. This will allow for
cooler ocean air to spread back across the coastal zones at that
time. But, offshore flow persists on to the north overnight,
such as at Astoria. Likely be one of those afternoons where
Newport is 59 with light south wind and Astoria is around 70
with an east wind in the late afternoon.

Changes gradually arrive Fri night into early Sat, as a front well
offshore approaches. Will see offshore flow gradually weaken Fri
night, with increasing clouds later Fri night into Sat am. Timing
still suggest showers or pockets of light rain spreading to the coast
by midday Sat, and pushing inland during the afternoon. Again, not a
strong front, as rainfall expected on Sat being 0.10 to 0.25 inch
along the coast/coastal mountains, and 0.02 to 0.10 for
lowlands form Cowlitz Valley through the Willamette Valley. Will
be much cooler on Saturday, thanks to clouds and onshore flow.
Highs only in the 50s along the coast, and lower to middle 60s
inland. /Rockey/JLiu

.LONG TERM...SUNDAY THROUGH WEDNESDAY...Onshore flow begins
developing Saturday night into Sunday. Cooler conditions are
expected Sunday as a result, with coastal highs in the mid 50s,
and right around 60 inland. Ensemble guidance points towards a
brief shortwave ridge impacting the area on Monday and Tuesday
morning, allowing for warmer temperatures potentially back into
the 70s. Tuesday and Wednesday see potential for another front,
allowing for light showers and cooler temperatures again. /JLiu

&&

.AVIATION...VFR thresholds prevail through the entire TAF period
with easterly flow aloft. North to northeast surface winds through
06z with wind gusts 15-20 kt through around 06z Friday. Winds
turn more east to northeast and calm for most areas after 06z
Friday as high pressure settles east of the Cascades, though the
central and southern Willamette Valley will remain mostly
northerly. However, east winds through the Columbia River Gorge
begin increasing after 06z Friday with gusts up to 35 to 50 kt
possible through Friday.

PDX AND APPROACHES...VFR conditions expected through the entire
TAF period. Easterly winds 10-15 kt with gusts up to 25 kt,
settling after 03-05Z Friday to 10 kt or less. Once winds have
settled after 05Z Friday, surface winds could turn westerly due
to influence of the Columbia River. This could cause directional
LLWS due to enhanced easterly winds aloft from strong flow through
the Gorge, though there is not enough confidence in this scenario
or strength of LLWS to include in TAFS. Winds expected to
increase to 10-15 kts and turn easterly again by 15Z Friday, which
would eliminate any directional LLWS concerns. -HEC

&&

.MARINE...Surface high pressure has shifted onshore this afternoon
as a thermal trough remains over western Oregon. This has caused
a tightening of surface pressure gradients, which will bring
elevated wind gusts to 25-30 mph through this evening, resulting
in choppy waters. A Small Craft Advisory remains in effect through
this evening. Pressure gradients will weaken tonight, as the
thermal trough continues to build north along the Oregon Coast,
causing winds to weaken. This pattern will continue through Friday
until a Pacific front approaches the waters Friday night,
breaking down the thermal trough and turning winds southerly.
Southerly winds increase through the day Saturday as the front
moves through the waters, with Small Craft winds likely into
Sunday.

General seas through Saturday afternoon of 4 to 7 feet at 15 to
17 seconds, consisting of a long period southwest swell. Swell
becomes westerly Saturday evening into Sunday, increasing general
seas to 9 to 11 feet at 9 to 11 seconds. -HEC

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Small Craft Advisory until 8 PM PDT this evening for PZZ251-
     271.
     Small Craft Advisory until 11 PM PDT this evening for PZZ252-
     253.
     Small Craft Advisory until 11 PM PDT this evening for PZZ272-
     273.
&&

$$

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