Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 252154

Area Forecast Discussion
National Weather Service Portland OR
254 PM PDT Wed May 25 2016

.SYNOPSIS...A deep marine layer and onshore flow will result in
plenty of clouds today and Thursday. Some areas of drizzle will be
possible each morning, with a few showers each afternoon, and
temperatures will be a few degrees below late May normals. Low
pressure dropping down the west coast of Canada will likely bring a
few more showers Thursday afternoon through Friday, along with a
reinforcing shot of cool air and onshore flow. Cool and showery
conditions look to stick around for the first half of Memorial Day
Weekend, but milder and drier weather appears to start Monday as a
ridge of high pressure builds in for the first part of next week.


.SHORT TERM...This afternoon through Saturday...As expected, most of
the area remains mostly cloudy this afternoon. A couple of spots have
attempted to break out, but filled right back in as diurnal heating
created more clouds. It appears the immediate coastline south of
Tillamook has cleared some, but clouds are already starting to pop up
again there. Could still see some drizzle or light rain this
afternoon, but any accumulation would be negligible.

Tonight and Thursday appear to be mostly a re-run of today, though
will see a few more showers across the north coast and SW Washington
Thu due to an approaching upper trough from the BC coast. As models
are now tracking the upper low inland across Washington, we will not
be in a favorable pattern for thunder despite reinforcing cool behind
the trough. Weather through Saturday will mainly be cloudy and cool
with light rain anywhere that sees any rain.

All the cloud cover will probably keep high temps 5-10 degrees below
seasonal averages (avg ~70 deg inland) through Friday. One caveat is
if cloud cover ends up less than expected Thursday, temps could end
up closer to normal due to stronger late May sun. /Bowen

.LONG TERM...Saturday night through Wednesday...While still some
uncertainty concerning the depth and precise strength of the upper
low, confidence continues to increase that the upper level low
moving south from B.C. over the weekend will take a more inland
track. However, with the upper level trough remaining over the
region on Sunday, a reinforcing shortwave will bring the potential
for some showers across the area. By late Sunday into early Monday
the trough shifts east as a upper ridge near 135W amplifies and
heights begin to rise over the region. Maintained a slight chance
PoP across the extreme northern coastal zones as well as portions of
southwestern Washington for Monday, but suspect that Monday will be
largely dry and warmer, back to near or a few degrees above seasonal
normals. As the upper ridge strengthens and moves over the region
during the early part of next week, expect temperature to further
warm - possibly nearing 80 degrees inland on Tuesday and Wednesday.
However, some differences emerge in the forecast models by midweek
with the GFS suggesting a slightly cooler pattern, so confidence is
only moderate for the end of the long term period.    Cullen


.AVIATION...Mostly VFR conditions across the area with cigs around
4000 to 5000 feet. Lower cigs along the far North Oregon and
South Washington Coast will probably remain around 3000 ft through
the afternoon. Will see broken cigs resolidify this evening with
cigs lowering to 1500-2000 feet along the Coast. Inland will
probably see areas of low stratus develop again Thursday morning,
with cigs lowering to MVFR at several terminals. This low stratus
inland will mostly lift to 4000 feet by 18Z Thursday with a few
sites holding on to MVFR cigs until early afternoon. Along the
Coast, cigs may lift to around 3000 to 3500 ft Thursday afternoon,
but should stay fairly solid through the day.

PDX AND APPROACHES...Cigs becoming broken this afternoon and
lifting to around 5000 feet. Cigs resolidify this evening and will
lower to around 3500 feet by 10Z. Chance for MVFR cigs after 14Z
around 2000 to 2500 feet.   -McCoy


.MARINE...Northerly winds across the waters this afternoon, with
winds gusting to 20 to 25 knots west of 20 nm offshore of the far
North Oregon and South Washington Coast. Will see small craft
advisory winds continue overnight into early Thursday morning.
Should see winds decrease in the morning before ramping back up
Thursday afternoon. Seas today are around 5 to 6 feet will
continue overnight, with seas getting up closer to 6 to 7 feet
Thursday morning. Thursday afternoon may see seas get close to 8
feet and become steep with dominant wave periods around 8 seconds.
Friday high pressure starts to break down with the approach of a
weak front. This means winds will generally be decreasing and
shifting to westerly in the afternoon and seas will be falling
back down to around 5 feet by Friday evening. Saturday winds shift
to southerly ahead of the front, with a chance of winds gusting
to 20 to 25 kt as the front moves onto the Coast Saturday
afternoon. Seas generally will stay around 4 to 5 feet through the
weekend. High pressure rebuilds over the waters early next week,
which means the return of northerly winds and choppy seas.


PZ...Small Craft Advisory for winds until 5 AM PDT Thursday for
     Waters from Cape Shoalwater WA to Cascade Head OR from 10
     to 60 nm.



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This discussion is for Northwest Oregon and Southwest Washington
from the Cascade crest to 60 nautical miles offshore. The area is
commonly referred to as the forecast area. is the U.S. government's official web portal to all federal, state and local government web resources and services.