Area Forecast Discussion
Issued by NWS Portland, OR

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518
FXUS66 KPQR 261554
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
854 AM PDT Sat May 26 2018

Updated Aviation section

.SYNOPSIS...Weather more typical of late May on tap for the region
over this weekend, continuing into next week. Will be cooler today,
as have remnants of a front that will maintain onshore flow. Will
even see spots of drizzle or sprinkles this morning. Plenty of
sunshine around region for Sunday, with temperatures inland well into
the 70s. Then a tad cooler but still near seasonable levels for late
May expected for Mon, and good part of next week. Next threat of any
moisture looks to be latter half of next week.
&&

.SHORT TERM...Today through Monday...Northwesterly low level flow has
brought much lower dewpoint temperatures and cooler temperatures into
the region overnight. Many areas mid to upper 40s this am, with few
spots such as Corvallis and Tillamook getting closer to 40 deg.

Weak front offshore will push to the coast this am, but will weaken
further as it shifts inland. At moment clouds cover not all that
impressive. But as the front works onshore, will quickly see clouds
thicken and spread inland this am.

Will keep occasional drizzle or brief light rain for coast and coast
mtns, as well as west slopes of the south Washington and far north
Oregon Cascades/foothills. Will also keep patchy morning drizzle for
other areas. Will see clouds slow to break up this afternoon, but
think will decent amount of drying aloft, should see clouds break up
later in the afternoon. Can not rule out a stray shower this
afternoon as marine layer gets mixed up a bit, but think odds fairly
low. Will leave out of forecast for now.

High pressure will then return Sunday and Monday, which should result
in a more June-like weather pattern with some morning clouds giving
way to sunshine. Afternoon temperatures getting back into the 60s
along the coast and well into the 70s inland.Rockey.

.LONG TERM...Monday night through Friday...The models show an
approaching and digging upper trough off the coast Monday night and
Tuesday, with a short wave that swings through Tuesday night and
early Wednesday. The upper trough remains in the region Thursday and
Friday through the GFS model is stronger than on the ECMWF. The main
effect is that it will be cooler, cloudier, with possibly some spotty
light precipitation especially north, though details are uncertain
later next week. Tolleson
&&

.AVIATION...A decaying front will move ashore this morning with
high pressure returning over the coastal waters in the
afternoon. The front will likely bring some drizzle during the
morning hours especially coast range westward, possibly even in the
inland areas for a while today. Cigs are mostly VFR but with some
areas of MVFR along the coast and possibly some inland areas as well,
especially if the drizzle spreads in. Conditions will improve to VFR
cigs late today and this evening, with breaks in the clouds this
evening. Should see some areas of MVFR conditions by morning Sunday
with localized IFR especially near the coast.

KPDX AND APPROACHES...Mainly VFR cigs today though there is a chance
of MVFR cigs midday if some drizzle develops from a dissipating
front. Conditions will be VFR cigs late today and this evening, with
clouds possibly breaking up in the evening. There is a chance of
MVFR cigs again for a few hours around and a bit after sunrise
Sunday. pt
&&

.MARINE...A weak cold front moves ashore this morning backing the
winds slightly. High pressure returns this afternoon and remains
over the northeast Pacific with lower pressure over northern
California. This will maintain north to northwest winds across
the coastal waters through the weekend and into the start of next
week. Gusts should remain generally between 10 and 20 kt with
seas holding between 5 and 7 feet. Northerly winds will likely
increase late Sunday night or Monday, which will likely create
steep and hazardous seas and winds gusting to 25 kt. /mh
&&

.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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