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566
FXUS66 KPQR 280627
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
1127 PM PDT Thu Jun 27 2024

Updated to fix formatting errors


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.SYNOPSIS...Scattered showers continue through this evening as
an upper level trough exits the region. Warm and dry conditions
return tomorrow, with temperatures warming into the upper 70s
and low 80s for interior valleys and upper 60s along the coast.
Another shortwave trough returns Saturday night into Sunday,
bringing another 15-30% chance of showers, mainly for the coast
and higher terrain. We`ll maintain consistently warm and dry
conditions through mid-next week. Temperatures begin to rise
Thursday, but uncertainty remains with how warm we will get.

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.SHORT TERM...
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Now through Sunday...The back end of an upper
level trough is pushing through the interior northwest as of
this afternoon. As the trough exits our region, expect lingering
shower activity over higher terrain and interior valleys from
the Portland/Vancouver Metro Area to Cowlitz County. Additional
QPF amounts will be minimal, except the south WA Cascades where
there could be some higher amounts around 0.10-0.20 inch.

Cloud cover will gradually decrease for most places as the
trough exits tonight, except along the coast. Weak ridging will
build tomorrow (Friday) over the Pacific Northwest, leading to
warmer and drier weather. Inland winds turn more northerly
tomorrow, supporting drier conditions. We`ll also see increasing
sunshine across the area tomorrow, leading to warmer afternoon
highs in the upper 70s to low 80s for interior valleys. NBM
suggests a 15-25% chance of highs exceeding 85 degrees for
interior valleys. Meanwhile, northwesterly winds along the coast
will keep conditions mild, with forecast highs in the upper 60s.

Saturday will remain warm and dry, with afternoon highs similar
to Friday. Chances for afternoon highs exceeding 85 degrees in
the interior valleys increase slightly to around 35-40%. Winds
will begin to turn more westerly as another upper trough near
the Gulf of Alaska dips southward toward the Pacific Northwest.
Not expecting impactful winds, but the strongest westerly wind
gusts will likely be in the central Columbia River Gorge around
20-25 mph.

Saturday night to Sunday, we`ll see increasing cloud cover as
the trough moves across the region. It`s not a very robust
trough, so conditions will be mostly dry. About a 15-30% chance
of showers is forecast along the coast and higher terrain as
orographics will be the main forcing for showers. Any shower
activity will mostly occur Sunday morning. By Sunday afternoon,
conditions dry out further and temperatures are forecast to
warm-up near or slightly above normal.       -Alviz


.LONG TERM...Sunday night through Thursday...WPC cluster
analysis are in general agreement of upper level ridging over
the NE Pacific. Most ensemble members keep the ridge axis far
offshore of the West Coast, so the current long term forecast
maintains warm, dry weather with inland highs in the upper 70s
to low 80s. Most ensembles keep this pattern through the middle
of the next week, but 15% of members transition our region to
more zonal flow by Tuesday/Wednesday. If the pattern turns more
zonal, we may see temperatures cool a few degrees. But for now,
expect pleasantly warm and dry weather through at least mid-
next week. Thursday, ensembles hint at temperatures warming up
further due to high pressure building, but uncertainty remains
with how warm we will get. -Alviz
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.AVIATION...Any lingering showers have come to an end as onshore
flow gradually weakens later tonight into Friday morning due to
high pressure building offshore. Still expecting clouds to reform
overnight as marine layer over region cools, with mostly VFR
inland and a mix of VFR to MVFR along the coast - best chance for
MVFR at KAST. As flow turns more northerly and then north-
northeasterly on Friday, will see clouds across the interior
dissipate between 15Z and 19Z, with clouds holding on bit longer
along the coast, especially north of Tillamook to Astoria. Once
conditions transition to VFR they`ll likely stay that way through
Friday evening.

PDX AND APPROACHES...Onshore flow will weaken overnight into
Friday, but VFR CIGS of 4000 to 6000 ft persist. However latest
HREF guidance does suggests a 30-40% chance for a period of MVFR
CIGS between 12-16z. Then clouds will be break apart and clear
out most likely between 16Z and 18Z with high confidence in VFR
conditions through the afternoon/evening. -Schuldt

&&

.MARINE...
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Weak low pressure remains onshore this evening, with
high pressure well offshore. Winds remain out the west to
northwest tonight. As the offshore high builds, will see all
winds turn north to northwest late tonight and Friday. At same
time, thermal low pressure will remain over far southwest Oregon
into northwest California. As such, will get back into some
northerly winds, with gusts up to 20 kt Friday through Saturday,
mainly during the afternoons/evenings to south of Tillamook.
Overall, seas staying in the 4 to 5 ft range.

Yet another weak low pressure arrives later Sat, with winds
flipping back to the west or southwest. Gradients weaker, so winds
not expected above 15 kt, while seas stay at 4 to 6 ft. Next
week, will see high pressure offshore build, with return of gusty
northerly winds on the waters for the afternoons/evenings.
                                                      /Rockey
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&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...None.

&&

$$

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