Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 211032
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
324 AM PDT Mon Aug 21 2017

.SYNOPSIS...Onshore flow will produce varying degrees of morning
clouds, afternoon sunshine and inland temperatures in the 70s and
80s for much of the next week. The coolest temperatures will likely
be late Wednesday and Thursday as a weak storm system brings a chance
for a few light showers to the area.


&&


.SHORT TERM...Today through Thursday...Fog product reveals marine
stratus congealing over the waters and pushing onto much of the
Oregon and Washington coastline. This stratus field is quite shallow
with cigs generally hovering a couple hundred feet AGL. This should
prevent too much inland penetration, but nonetheless, should see some
marine clouds into at least the Kelso-Longview area by daybreak...and
perhaps even into the eastern PDX metro towards 7-8am. Given little
change in the pressure pattern, wind fields and the solar eclipse
should begin to limit solar insolation around the time stratus
typically begins to dissipate along the coast, suspect those along
the coast that are currently cloudy will remain so through the
duration of the eclipse. The good news is that away from the Columbia
River and Willapa Bay, the marine stratus should not extend more than
a few miles inland. It should be noted that there will be a few
passing high clouds this morning for areas that are not socked in the
marine clouds. However, these clouds should be considerably thinner
and more transparent than the mid-high level clouds observed
yesterday.

Otherwise, expect inland high temperatures to top out in the mid to
upper 80s today and Tuesday. Thunder chances look to remain south and
east of the region Tuesday and Wednesday afternoon and evening. The
next front will approach the region Wednesday and bring cooler
temperatures, increased cloud cover and a chance for some light rain
showers Wednesday night and Thursday. /Neuman


.LONG TERM...Thursday night through Monday...Shortwave ridging should
build over the Pacific Northwest and bring a return to more sunshine
and warming temperatures Friday and Saturday. In fact, some models
suggest another hot spell and dangerous fire weather conditions are
possible late in the weekend and/or early next week, but still too
early to say much more than that at this point. /Neuman


&&


.AVIATION...Stratus deck has filled in along the coast now with
ceilings between 200 and 400 feet. KAST has briefly broken out of
the stratus, but expect the stratus to return and remain through
the morning. The biggest question will be how quickly the stratus
clears. Given that 925 and 850 winds are slowly becoming more NE
between now and 18Z, expect the stratus to clear quite
quickly...possibly even in time for the eclipse. However, given
the slower daytime heating due to the eclipse, this may also
limit mixing and cause the stratus to linger longer than
otherwise expected.

KPDX AND APPROACHES...VFR conditions through the period. Still a
small possibility of a few scattered clouds this morning near the
terminal, but expect mostly clear skies. /Bentley


&&


.MARINE...A persistent weather pattern will result in little
change in the marine weather the next several days. High pressure
will continue over the NE Pacific with a thermal trough of
varying strength along the south Oregon Coast. This will lead to
small craft strength winds again today in central waters. Winds
should be below small craft strength through the remainder of the
week before northerlies strengthen again by the weekend as the
thermal trough strengthens again.

Seas will remain small but steep through the period. Dominant
periods will remain between 8 and 10 seconds. A rough bar is in
effect for the very strong ebb this morning. Otherwise, no sea
driven headlines should be needed this week. /Bentley


&&


.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Small Craft Advisory for winds until 11 PM PDT this evening for
     Coastal Waters from Cascade Head OR to Florence OR out 60
     nm.

     Small Craft Advisory for Rough Columbia River Bar until 7 AM
     PDT this morning.

&&


$$

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This discussion is for Northwest Oregon and Southwest Washington
from the Cascade crest to 60 nautical miles offshore. This area is
commonly referred to as the forecast area.



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