Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 282112
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
210 PM PDT Wed Jun 28 2017

.SYNOPSIS...An upper ridge will traverse the area Thursday and Friday
for sunny skies after perhaps brief morning clouds. Over the weekend
and into early next week, the flow turns more westerly for the
seasonable pattern of morning clouds and afternoon sunshine.
Temperatures will be slightly above average Thursday and Friday, and
then close to normal thereafter.

&&

.SHORT TERM...Tonight through Sunday...Clouds have been relatively
slow to break up today, but visible satellite loop shows active
mixing/clearing now underway. Should be a very pleasant late
afternoon and evening.

The tranquil summer pattern continues through the weekend. As an
upper ridges approaches the area Thursday and moves overhead Friday,
the marine layer thins for considerably more sunshine and valley
temperatures climbing into the lower-to-mid 80s. Westerly flow
returns Saturday with the approach of a weak, albeit dry, shortwave.
This should deepen the marine layer, particularly on Saturday, for
the typical sunny after morning clouds pattern this weekend.

The models/ensembles indicate some lower-end CAPE (250-750 J/kg)
over the Cascades during max heating Friday afternoon/evening and
again Saturday afternoon/evening. An isolated thunderstorm over the
elevated terrain, especially central/southern Cascades, is not out
of the question, but any storms that manage to break the cap would
be few and far between, and quickly move eastward away from the CWA.
DRB

.LONG TERM...Sunday night through Wednesday...Typical summertime
pattern continues through at least the first half of next week.
Fairly zonal flow with a series of weak shortwaves will bring marine
clouds to the coast overnight Sunday night, with a chance for
drizzle or light rain on the north coast through the morning hours.
Another, weaker impulse will bring clouds back to the north coast
Monday night into Tuesday morning, with another chance for some
light rain or drizzle on the north coast. Going into midweek, expect
less and less morning clouds. Temperatures are going to stay around
normal early next week, gradually increasing midweek. -McCoy

&&

.AVIATION...Today is similar to Tuesday as tops have been 040-045
and bases near 015-025. Timing of clearing inland today similar
to Tuesday at most sites. The central coast will have the best
chance of much clearing at the coast. MVFR cigs return inland
later tonight and Thursday morning with best coverage in the
north and southward along the Cascade foothills, with possibly
less coverage in the west side of the Willamette Valley. Clouds
clear back to near the coast Thursday afternoon, with the best
chance of clearing at the coast in the south.

KPDX AND APPROACHES...MVFR stratus will give way to VFR
conditions early to mid afternoon, then MVFR cigs return late
tonight through a good part of Thursday morning before more VFR
Thursday afternoon. pt
&&

.MARINE...Not much change in overall weather pattern, as we will
see rather persistent higher pressure over the NE Pacific, with
thermal low pres staying well south over NW California. Gradients
will not be all that strong, so northerly winds generally
staying under 20 kt. Winds will be less Thursday than today,
increase a little Friday, decrease Saturday, then increase again
possibly Sunday and Monday.

Wave models have been running 1-2 ft below the observed values
this morning but are closer this afternoon, and with short
periods of only 7 or 8 seconds, leading to choppy seas. Will
maintain the Small Craft Advisory for hazardous seas issued
earlier today through this evening and let the next shift see if
we need to extend it any further. We should see seas decreasing
later tonight and Thursday. Seas will then remain below Small
Craft Advisory values through the weekend. pt
&&

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

     Small Craft Advisory for Rough Columbia River Bar from 7 PM
     this evening to midnight PDT tonight.

     Small Craft Advisory for Rough Columbia River Bar from 8 AM to
     11 AM PDT Thursday.

&&

$$

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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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