824
FXUS66 KPQR 122230
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
330 PM PDT Fri Jul 12 2024

.SYNOPSIS...High pressure remains over the next several days
with a weak disturbance passing through the overall flow on
Sunday. Will see a more persistent westerly flow starting that
day. Less than a 10% chance of thunderstorms along the Cascades,
specifically near the northern Oregon Cascades. Northerly winds
will increase through the Willamette Valley on Tuesday into
Wednesday.

&&

.SHORT TERM...Now through Monday...Very minimal change in
sensible weather as a high pressure ridge remains anchored over
the northeast Pacific. Temperatures will remain seasonably warm
with highs in the upper 80s to 90s (Fahrenheit) through most of
the weekend. Flow though will remain onshore through the period
with a sea breeze each afternoon. No real concerns at this
time.

On Sunday into Monday we will experience the first real shift in
weather though the impacts will be minimally experienced in
northwest Oregon and southwest Washington. A 500 mb low will
pass over the region starting very early Sunday morning and will
track over northern Washington. The flow will become more
steadily westerly so will see an influx of low level moisture
which will cause humidity to rise. Unfortunately - or
fortunately depending on your preferences - temperatures will
only lower by a few degrees in the lowlands. High resolution
models are suggesting around a 10% chance of thunderstorms over
the Mt Hood Natl Forest and Columbia River Gorge on Sunday
morning, however, without more moisture, we will struggle to get
charge separation enough to cause those storms to manifest.
However, cannot rule them out.  -Muessle



.LONG TERM...Tuesday through Friday...Not much to write home
about as high pressure once again builds on Tuesday. One thing
that could form is positively tilted ridge which would increase
the pressure gradient along the coast and force winds to become
more northerly. This would cause winds to increase, especially
in the southern Willamette Valley and along N-S aligned areas.
At this point, most ensemble guidance suggests the moisture and
thunderstorm chances will remain over south central and
southeast Oregon. Will keep the Lane County Cascades dry, but
maintain some cumulus buildups for that area.

Does appear that will see bit warmer temperatures next week,
especially Tuesday through Thursday. Guidance has been trending
warmer, but still, afternoon highs expected to be lower to middle 90s
for the interior lowlands of the Willamette Valley, Columbia Gorge,
and lower valleys of the Cascade foothills.-Muessle/Rockey


&&


.AVIATION...Surface high pressure over the northeast Pacific and
thermally induced lower pressure over the Great Basin will
produce primarily VFR conditions inland and a mixture of IFR and
MVFR conditions for the coast through 00z Sunday. While
conditions are currently VFR along the coast, expect conditions
to deteriorate rapidly with a >80% chance that conditions end up
in low end MVFR or IFR thresholds in the next 2-4 hours as
marine clouds push onto the coast. The most uncertainty lies in
how far the marine clouds will move up the Columbia River
tonight. At this point, it appears there is a less than a 20%
chance for MVFR ceilings to reach KPDX and KTTD around 13-15z
Saturday. It should be noted that some residual smoke and smog
across the general area will obscure distant topography, but
visibilities should continue to remain well above 6sm.

PDX AND APPROACHES...Surface high pressure over the northeast
Pacific and thermally induced lower pressure over the Great Basin
will maintain predominantly VFR conditions and a typical
northwesterly wind regime through 00z Sunday. /Neuman


&&


.MARINE...High pressure will maintain northerly winds across the
waters for much of the next week. Winds will generally be
strongest off the central coast of Oregon and lightest off the
mouth of the Columbia River each day. Winds will typically peak
each day in the late afternoon and evening hours.

Probabilities of 20 kt winds or greater do decrease substantially
(to less than 20%) across the waters off even the central coast
of Oregon towards next Tuesday and Wednesday. In the meantime,
seas will primarily be a hybrid of fresh swell/wind-driven waves
through the weekend. /Neuman


&&


.PQR WATCHES/WARNINGS/ADVISORIES...

OR...None.
WA...None.
PZ...Small Craft Advisory until 5 PM PDT Saturday for PZZ252-253-
     271>273.

&&


$$

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