Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 301634
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
933 AM PDT Mon May 30 2016

.SYNOPSIS...An upper level ridge will build into the Pacific
Northwest today, bringing clearing skies and drying weather to
southwest Washington and northwest Oregon. The ridge will produce
warming temperatures over the next couple of days with light offshore
flow pushing inland temps close to 90 on Tuesday. Onshore flow will
start to develop Wednesday to take the edge off the heat. Though
daytime temperatures will be slightly cooler the latter half of next
week, they will remain well above normal.

&&

.SHORT TERM...(Today through Thursday)...The upper ridge of high
pressure seen in water vapor pictures along 130W early this morning
is expected to shift east to the coast by the end of the day, and
then inland over the Pacific NW by Tue. The classic cycle of a
thermal trough is the result, with models showing the trough of
thermally induced low pressure along the S Oregon coast building
north up the coast today and tonight, then shifting inland into the
Coast Range during the day Tuesday. With the resulting turn to
offshore flow, dry and mostly sunny weather is expected for the
region today and Tuesday. Temperatures will quickly warm well above
normal both today and Tuesday. Models continue to depict 850 mb
temperatures over the region climbing to around 18 degrees C by
Tuesday afternoon. This, in combination with offshore flow, will push
temperatures inland to around 90 degrees. Meanwhile, temperatures at
the coast will likely reach into the 70s relatively early in the day,
before flow turns onshore in the afternoon and the marine air will
prevent additional heating in the later afternoon hours.

The upper ridge continues to advance inland Tuesday night and
Wednesday and flattens out a bit, and the low-level flow will turn
more onshore as the surface trough pushes east of the Cascades.
Expect low stratus or fog to return to the coast Tuesday night as the
cooler marine air returns. This should noticeably modify temperatures
Wednesday along the coast, but temperatures inland will remain well
above normal and only cool a few degrees. The remnants of a weak
shortwave passing well to the north could bring some light showers
across the far northern and coastal portions of the area late
Wednesday through Thursday. Heights continue to fall just a bit, but
expect temperatures to remain around 80 inland on Thursday.   /Cullen

.LONG TERM...(Thursday night through Sunday)...The models have come
to the consensus that upper level ridging will persist through at
least Saturday. This will keep dry weather and warm temperatures over
the region, with afternoon highs at the coast in the upper 60s to
lower 70s. The interior will likely see highs stay in the 80s. With
overnight lows in the upper 50s to mid 60s and light winds expected
late next week we could be in for some unpleasant nights. However, a
slight onshore gradient should keep temperatures from getting out of
hand. Another weak shortwave on Sunday could bring a slight chance of
thunderstorms to the Oregon Cascades, but confidence remains low. /64

&&

.AVIATION...VFR conditions at all TAF sites through Monday night.
Gusty northwesterly winds at KAST and KONP this afternoon and
evening.

PDX AND APPROACHES...VFR conditions expected through Monday night.
 /Bentley

&&

.MARINE...High pressure in the northern Pacific will shift
northward Monday with a thermally induced low developing across
northern California and southern Oregon. This combination will
lead to gusty north winds this afternoon through Tuesday then
weakening on Wednesday. A small craft advisory in effect for all
waters through 12Z Tuesday and continues for the outer waters
through Tuesday evening. There will probably be small craft
advisory winds for the nearshore waters Tuesday afternoon and
evening.

Seas between 4 and 5 feet today and should become choppy
especially during the afternoon and evening with the stronger
diurnal winds. Seas will increase slightly due to a gusty
northerly fetch for the first half of the week, do not expect
this rise to be more than a couple of feet. /Bentley

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Small Craft Advisory for winds from 2 PM this afternoon to 11
     PM PDT Tuesday for Waters from Cape Shoalwater WA to
     Florence OR from 10 to 60 nm.

     Small Craft Advisory for winds from 2 PM this afternoon to 5 AM
     PDT Tuesday for Coastal Waters from Cape Shoalwater WA to
     Florence OR out 10 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.


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