Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 211008
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
308 AM PDT Thu Jun 21 2018

.SYNOPSIS...Strong onshore flow keeps plenty of clouds across the
region today through Fri morning, along with some patchy drizzle.
Much cooler, with near seasonable temperatures expected. Then will
see much less in way of clouds for the weekend into early next week,
with warmer, but not hot. temperatures.
&&

.SHORT TERM...Today through Saturday...Upper level feature that
brought thunderstorms the region yesterday is now pulling away over
eastern Oregon. But, still just enough circulation that can not rule
out a few showers over the crest of the Oregon Cascades, mainly this
morning. Will keep 20 pct pops for that area.

In its wake is strong onshore flow, with marine clouds covering most
of western Washington and western Oregon. Models continue to indicate
very slow break up of the marine stratus today, and likely will not
see much in way of any breaks in the clouds until after 3 or 4 pm
today. As such, will have temperatures much cooler, with 50s to lower
60s on the coast, and lower to middle 70s inland. Can not rule some
patchy drizzle this am as well, mainly along the coast and over
against the foothills of the Cascades.

Overall pattern not changing much for tonight and Fri, as will have
continue moderate onshore flow. So, should see marine stratus reform
over most the region tonight. Temperatures will be up a tad on Fri,
as think the clouds will break up earlier in the afternoon.

Ridging gets bit stronger on Sat, with increasing northerly flow in
mid levels. This will lead to patchy morning clouds inland, then mild
and sunny with inland temps back into the upper 70s. But due to bit
stronger north winds, coast stays in the lower to mid 60s. Rockey.

.LONG TERM...Saturday night through Tuesday night...A surface thermal
trough strengthens along the N. CA and S. OR coast Saturday night as
high pressure dominates inland, and offshore flow should keep marine
clouds off the coast Saturday night. A sunny start Sunday will allow
slightly warmer temperatures Sunday afternoon with high temperatures
remaining above the seasonal normals. Models are in excellent
agreement that an upper level trough will send a series of shortwave
troughs over the region Sunday night through Tuesday for increased
morning clouds and cooler afternoon temperatures. ~TJ

&&

.AVIATION...Onshore flow will keep the coast socked in with
marine stratus today and tonight. Expect predominately MVFR
conditions along the coast the next 24 hours, but occasional
periods of IFR cigs are possible this morning as the marine
layer deepens.

Marine stratus filtered into the interior overnight and brought
cigs between 1500-2500 ft. Expect MVFR conditions in the interior
through early this afternoon. Marine stratus will gradually lift,
with conditions becoming VFR between 19-21Z. MVFR marine stratus
likely returns late tonight/early Friday morning.

KPDX AND APPROACHES...MVFR marine stratus around 2000 ft will
persist through early this afternoon. Stratus will gradually
lift, with conditions becoming VFR by 21Z. MVFR conditions
possible after 09Z tonight. /64

&&

.MARINE...A weak disturbance will move across the waters today,
but winds will remain relatively light. High pressure rebuilds
over the waters on Friday and lingers through the weekend. The
thermal low will strengthen over northern California and southern
Oregon over the weekend and bring gusty northerly winds to 30 kt.

Seas remain around 3 to 5 ft through Friday as we remain under
relatively benign conditions. With winds ramping up this weekend,
seas may build up to 5 to 7 ft by late Sunday-early Monday, and
seas may become choppy. /64/McCoy

&&

.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.



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