273 
FXUS66 KPQR 101015
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR 
314 AM PDT Fri Aug 10 2018

.SYNOPSIS...High pressure will shift east of the Cascades later
today, bringing an end to this round of hot weather. An upper level
low will pass to our north late Friday and Saturday, resulting in
cooler and cloudier weather, along with some rain. Warmer weather
returns next week as high pressure rebuilds across the Pac NW.

&&

.SHORT TERM...Friday through Sunday...Models continue to show the
upper level low approaching the coast on Friday and moving across the
region late Friday and Saturday. Will see onshore flow increase
today, but with the low now expected to move across the area on
Friday night this increase will be a little weaker. This means there
will likely be less clouds in the interior today and the break in
temperatures won't be quite as big as it was looking. Upped
temperatures slightly for today, now looking at mid to upper 80s in
the interior.

Much cooler and cloudier weather arrives tonight and Saturday as
the low finally moves across the forecast area. Expect light rain
showers to move onto the coast this evening and spread inland
through the day Saturday. Models are now showing a decent amount of
instability Saturday, mostly focused on the Washington side of the
forecast area as the track of the upper low has shifted north. Added
a slight chance of thunder to the S Washington coast Saturday morning
and most of the Washington side of the forecast area Saturday
afternoon. It will be dependent on the low track though, so if the
low shifts even further north, it would likely displace thunder
chances well into Washington and outside of the local area.

Showers will taper off from south to north starting Saturday evening.
It looks like they may linger longest into Sunday along the S
Washington and N Oregon coasts, maybe not completely ending until
later Sunday morning there. However, accumulations will be light.
Sunday will generally begin a warming trend with rising heights as
the low exits to the northeast. Bowen

.LONG TERM...Sunday night through Thursday...Ridging looks to build
back up over the area early next week, with temperatures climbing
back up into the 90s inland starting Monday. However, there is some
indication that the ridging could have trouble building as strong as
it has this past week due to a somewhat steady stream of disturbances
skirting the area. This would suggest that next week won't be quite
as hot, with temperatures peaking in the low to mid 90s instead of
approaching 100 degrees. Starting midweek, the models diverge pretty
significantly, likely due to poor handling of the Eastern Pacific
tropical leftovers, so confidence beyond about Wednesday is low.
Bowen

&& 

.AVIATION...Onshore low level flow deepening the marine layer
slightly. KOTH-KSEA pressure gradient is 4.3mb up from 1.5mb 24
hours ago. Will probably see IFR cigs move into the south
Willamette Valley this morning affecting KEUG and KCVO and
vicinity. Some models indicate low cigs may also affect KSLE, but
those models have been too aggressive in bringing the clouds
inland. IFR cigs also making it up the lower Columbia River past
KKLS, but do not think it will make it to KPDX area. The marine
layer should deepen through Saturday as an upper level trough and
low level front approach. This should bring widespread low VFR or
high MVFR cigs inland tonight. The mid level smoke haze will 
also linger today, but should begin to improve tonight into 
Saturday.

KPDX AND APPROACHES...VFR conditions expected to persist today,
then chances for low VFR or high MVFR cigs inland tonight. Mid-level
haze will persist, but should begin to clear tonight into 
Saturday. /mh

&&

.MARINE...The marine conditions are benign with significant wave
heights 3 feet or less, and light NW winds with weak high
pressure over the waters. Strong ebbs the next few days may 
result in choppier conditions across the bars at times. A weak 
surface trough will bring a round of light S-SW winds early
Friday morning as a low pressure system currently near 135W 
moves towards the B.C. coast. The S-SW winds will increase 
Saturday as the low holds near the B.C. coast, but do not 
anticipate any headlines. Weak high pressure and north winds 
return Sunday then strengthen some through the week. Seas will 
remain 3 to 4 feet through the weekend, then build to 5 or 6 feet
with the north winds next week. /mh/Pyle

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...None.

&&

$$

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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 CWA or forecast area.