511
FXUS66 KPQR 051739
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
1039 AM PDT Wed Jun 5 2024

&&

.SYNOPSIS...
High pressure is bringing a gradual end to the cloudy and
damp weather from the past several days. Morning clouds will
eventually break up today, allowing temperatures to recover to
seasonable levels. The warming trend will continue 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...Now through Thursday Night...
Today through Friday...Rain has just about come to an
end across the Pacific Northwest as high pressure strengthens over
the region. Enough moisture lingers in the low levels for persistent
clouds across the forecast area, but subsidence will eventually break
up these clouds as this morning progresses. Assuming there is a good
deal of sunshine this afternoon, highs should easily reach the 70s
for the inland valleys.

The warming trend continues through Thursday and Friday, with Salem
850 mb temps climbing to around +14 deg C Thursday afternoon and into
the +17 to +20 deg C range Friday afternoon, based on 00z GEFS and EC
ensemble data. This should support inland valley highs in the 80s
Thursday and possibly near 90 for 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.  Weagle

.LONG TERM...Saturday through Tuesday...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 70% 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 20-25 percent chance to reach 90 degrees
and around a 10 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 building over the region today and will
bring warmer temperatures and drying. Clouds have rapidly
dissipated across much of the area, except for lingering
scattered clouds across the Coast Range and southern Willamette
Valley. VFR is expected to continue through early Thursday. Light
winds will becoming northerly at the coast with gusts to 25 kt in
the afternoon and evening. For inland areas expect afternoon north
to northwest winds 6 to 10 kt in the afternoon and evening.

PDX AND APPROACHES...VFR expect through the forecast period.
Light winds turn northwest around 10 kt later this afternoon into
the evening hours. -Batz/mh

&&

.MARINE...High pressure builds over the waters today to bring
summer type pattern with northerly winds across the waters.
Expect wind gusts in the 20 to 30 kt range next couple of days.
In addition to winds, seas will be rather steep. Seas today
starting around 14 feet at 14-15 second period will gradually
subside over the next several days to around 9 ft Thursday and
perhaps to near 5 ft by the weekend. /mh

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Small Craft Advisory until 5 AM PDT Thursday for PZZ210-251-
     271.
     Small Craft Advisory until 6 AM PDT Friday for PZZ252-253-272-
     273.
&&

$$

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