645
FXUS66 KPQR 102233
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
333 PM PDT Wed Jul 10 2024

.SYNOPSIS...While our long duration heatwave has finally come
to an end daytime temperatures still remain above normal going
forward. Expect highs mainly in the 80s to middle 90s for the
warmest spots. Lot cooler along the coast, where low clouds and
fog will keep it in the upper 50s to middle 60s into the
weekend. Overall, not much change into next week, as high
pressure centered to our east will maintain dry condition, with
warm temperatures inland. But at least it won`t be as hot as
recent days.

&&

.DISCUSSION...Tonight through next Tuesday...Broad albeit weak
west-southwesterly flow has begun to increase across the region
helping to knock down temperatures this afternoon headed into
the evening around 10 degrees compared to the record breaking
heat experienced this past Tuesday. This is all thanks to the
axis of an upper-level ridge of high pressure nudging eastward
into the Rockies while also shifting the surface thermal trough
east of the Cascades. All in all this`ll grant us at least some
improvement as far as temperatures are concerned but the weak
westerly flow/marine influence won`t be robust enough to drop
highs back to normal. Anywhere from roughly 80-84 degrees is
where high temperatures should typically end up this time of
year in the Willamette Valley.

Going forward, not much pattern change is anticipated through
rest of the week into the coming weekend with rather slow large
scale upper-level progression maintaining warm southwest flow
aloft. This will keep inland areas above normal in the 80s to
lower 90s during the afternoon hours. The NBM ensemble suggests
a 25-50% chance to meet or exceed the 90 degree mark Thursday
and Friday across the Willamette Valley into the lower Cascades
Valleys. These probabilities increase on Saturday closer to
50-75% due to an approaching weak upper-level shortwave trough
off the coast increasing the southerly component of the flow
aloft (More of the other ramifications we`re watching with this
feature in the paragraph below). Then guidance suggests highs
drop back into the mid to upper 80s by Monday and Tuesday of
next week as onshore flow strengthens slightly.

Outside of temperatures, conditions are expected to remain dry
for the vast majority of the forecast area through the period.
But as the center of the high pressure to our east meanders
towards the Four Corners region late week and an accompanying
cutoff low off the California coast moves northward, we`ll need
to closely watch monsoonal moisture working its way towards the
region this weekend. At this point, most ensemble guidance
suggests the moisture and thunderstorm chances will remain just
to our south and east of the region, however there is a 5-10%
chance that the thunderstorm threat impacts our higher Cascades
around Sunday/Sunday evening, primarily far eastern Lane
County. Should the plume of mid-level monsoonal moisture trend
further west these probabilities may need to be increased, but
for now the threat appears low with the 12z deterministic
guidance actually shifting the axis of moisture further east.
-Schuldt/Rockey

&&

.AVIATION...High pressure remains over the area, maintaining VFR
thresholds under clear skies for inland terminals. Expect northerly
to northwesterly wind gusts to around 20 kt through the remainder
of the afternoon. Late evening, winds are expected to weaken
below 10 kt. Tonight, there is high confidence in marine stratus
returning, bringing IFR/MVFR conditions to KAST and KONP by 03-05z
Thu. There is also a 15-30% chance of IFR/MVFR cigs for northern
Willamette Valley terminals between 12-16z Thu, as model guidance
hints at marine stratus potentially filtering in through the Lower
Columbia River Valley. Otherwise, predominately VFR thresholds
under mostly clear skies tomorrow, with marine stratus dissipating
again by 18-20z Thu.

PDX AND APPROACHES...VFR under clear skies through the TAF period,
with a 15-30% chance of IFR cigs between 12-16z Thu. Winds this
afternoon will be northwesterly 10-13 kt, with gusts around 20 kt.
Expect winds to ease below 10 kt around 08-10z Thu. -Alviz

&&

.MARINE...High pressure will maintain gusty northerly winds the
remainder of the week. Tightening pressure gradients will lead to
strengthening of winds tonight into tomorrow (Thursday). Expect
northerly winds of 15-25 kt with gusts up to 30 kt. Seas will be
wind-driven and choppy at times, building to around 6-8 ft
tomorrow. There is high confidence for small craft conditions
through at least late Thursday night, so the Small Craft Advisory
for all marine zones has been extended through 5 AM PDT Friday.
The Columbia River Bar has also been added to the Small Craft
Advisory, beginning 11 AM PDT Thursday.     -Alviz


&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Small Craft Advisory from 11 AM Thursday to 5 AM PDT Friday
     for PZZ210.
     Small Craft Advisory until 5 AM PDT Friday for PZZ251>253-
     271>273.
&&

$$

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