591
FXUS66 KPQR 052246
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
345 PM PDT Wed Jun 5 2024

&&

.SYNOPSIS...High pressure will maintain the warming trend with no
precipitation through Friday, though recent rain will add a touch of
humidity to the air. Temperatures will be well above normal by
Friday, especially inland. Above normal temperatures likely linger
through the weekend, though onshore flow will begin to moderate
temperatures over the weekend.

&&

.SHORT TERM...Tonight through Friday night...High pressure persists
over the region through the end of the week, allowing for dry
weather and warming temperatures. The upper level ridge strengthens
over the Pacific Northwest on Friday which will likely bring the
hottest temperatures of the week, especially inland, where highs are
expected to be around 15-20 degrees above normal. NBM guidance
suggests there is around a 40% chance that late afternoon temps
reach or exceed 90 degrees in the Portland metro on Friday. 850 mb
temps climb to around +15 deg C Thursday afternoon and into the +17
to +20 deg C range on Friday, based on 00z GEFS and EC ensemble
data. This should support inland valley highs in the lower 80s
Thursday and upper 80s Friday. Coastal areas will also see plenty of
sunshine Thursday and likely Friday, but midday and afternoon sea
breezes should hold highs in the mid to upper 60s for the beaches
and 70s for the coastal communities.

Low clouds may increase along the coast as early as Friday as marine
inversions strengthen, but this is not certain. Additionally, some
forecast models suggest some weak shortwave energy will dribble into
SW Oregon as early as Friday, potentially enhancing mid-level
instability for the Lane County Cascades. For now, it appears the mid
levels remain too dry for thunderstorms Friday, and a westerly
component to the flow aloft would likely carry any showers/t-storms
quickly east of the Cascade crest. Therefore we opted to keep thunder
chances below 10% Friday afternoon, as the NBM did.  DH/Weagle

.LONG TERM...Saturday through Wednesday...No changes, previous
discussion follows. The more progressive solutions appear to have
won out for the weekend, as the upper ridge axis is likely to move
east of the Cascades Saturday. This will focus thermal low pressure
over the Columbia Basin, allowing onshore flow to bring its
moderating influence to temperatures as early as Saturday.
Temperatures will still be above normal inland, as 500 mb heights
remain well above normal, representing the warm air mass in place.
But the onshore low-level flow and a weak shortwave will likely
deepen the marine layer enough to keep temps in the 80s for the
inland valleys Saturday afternoon. In fact, NBM probabilistic
guidance only shows a 60% chance Eugene will reach 80 degrees
Saturday afternoon, when they were suggesting 90s not too long ago.

Models diverge somewhat on how the ridge evolves beyond Saturday as a
trough approaches from the Pacific, with some solutions directing
this energy north into Canada while others try to develop a split
flow pattern and shunt some energy south towards CA as a cutoff low.
In terms of sensible weather impacts, expect mostly dry conditions to
persist across northwest Oregon and southwest Washington with
temperatures on Sunday dropping a few degrees into the upper 70s or
low 80s but generally remaining above seasonal norms. WPC ensemble
clusters show general agreement on maintaining high pressure over the
Pacific Northwest through early next week, while differing on
precise magnitude and placement. Temperatures are therefore
expected to remain above normal through the period, but with a
wider range of outcomes. This is reflected by NBM probabilistic
guidance which shows a 10-15 percent chance to reach 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 inly in the mid 70s on
Tuesday. 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. Weagle/CB

&&

.AVIATION...High pressure will remain in control of the region
into the weekend, keeping conditions warm and dry. VFR conditions
are expected to prevail through the TAF period under mostly clear
skies. Winds along the coast will be northwesterly at around 10
knots with gusts up to 20 knots through the evening. Winds inland
will remain west/northwesterly around 5-8 knots before becoming
light and variable overnight. Winds pick back up after dawn from
the north at around 10 knots along the coast and 5 knots inland.

PDX AND APPROACHES...VFR expect through the forecast period.
Northwest winds around 5-7 kt become light and variable overnight.
-Batz

&&

.MARINE...High pressure over the waters will maintain northerly
winds into the weekend. Wind gusts in the 20 to 25 kt range will
be possible through Thursday night into early Friday morning. In
addition to winds, seas will be rather steep. Seas will remain
steep, 10-14 feet at 12-14 feet into Thursday morning and will
gradually subside to below 10 feet later Thursday at 11 seconds. A
Small Craft Advisory remains in effect for all zones through 5AM
when PZZ271 and PZZ251 fall off as winds relax across the area.
The rest of the waters remain under an advisory through Thursday
night.

Rough Bar conditions are also expected through 8AM due to gusty
winds and seas around 10 feet. A very strong ebb current is also
expected at 5AM and will maintain dangerous conditions into early
Thursday morning. -Batz

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

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

     Small Craft Advisory until 5 AM PDT Thursday for PZZ251-271.

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

$$

www.weather.gov/portland

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