Weather Service Report

FXUS66 KPQR 150956 AAA

Area Forecast Discussion
National Weather Service Portland OR 
256 AM PDT Mon Oct 15 2018

.SYNOPSIS...High pressure over the region will produce an extended
stretch of mild days, cool nights and clear skies through the
week. The high pressure looks to break down next week for a decent
chance for rain.


.SHORT TERM...Today through Wednesday...A high amplitude upper ridge
continues over the NE Pacific. Storm systems over the north Pacific
are being steered northward along the periphery of the ridge.  The
ridge will flatten some over the next several days as a deep trough
over eastern north America shifts east.  While dry weather will
remain with us, the low level offshore flow will weaken.  This will
result in more widespread valley lows in the 30s since winds will
ease. But with the dry air mass - dewpoints in the mid 20s to mid 30s
- in place and shallow inversions expect lowland highs in the 60s to
low 70s.  

Given growing season for most of our valley locations typically 
holds out until Oct 20th or Nov 1st depending on the zone there is a
a Freeze Warning through early this morning for the central and
southern Willamette Valley and the Lower Columbia River/I-5 corridor
between Vancouver and Castle Rock. Admittedly a few of these
locations have already experienced frost with low temperatures
dropping down into the 33-35F range a couple times already this fall,
but they have yet to officially hit 32F. /mh /Neuman 

.LONG TERM...Wednesday night through Sunday...Strong high pressure
appears likely to continue across the Pacific Northwest into next
weekend. More subtle details of whether or not the flow will be
onshore or offshore Thursday and Friday remain somewhat uncertain so
kept temperatures near to slightly above average during this time.
Models do suggest upper level high pressure will begin to shift east
of the region towards next weekend, which should open up the region
to increasing southwesterly flow aloft and eventually allow cooler
marine air to filter into the region. /Neuman


.AVIATION...VFR conditions under clear skies continue today. 
Winds have eased and will remain light/variable at most locations
away from the Columbia River Gorge, with the exception of around
KONP where breezy east winds also continue. Some of the 
sheltered valleys may see some shallow fog form, but the chance 
of this occurring at any terminal remains around 5 percent at 
best, so will continue to exclude any mention from the TAFs. 

KPDX AND APPROACHES...VFR through Monday. Surface winds
light/variable overnight, but will again be east to 10-12 kt
during the daylight hours on Monday.   Cullen


.MARINE...High pressure maintains over the waters through much of
this week. Surface thermal low pressure pushes inland, which will
allow winds to ease over the waters. Small craft advisory will
expire at 3 AM as planned. The offshore pattern weakens early 
this week with gusts dropping back down to the around 15 kt
Monday and generally light winds across the waters for the
remainder of the week.

Sea conditions remain rather choppy with a pair of small swells
and the residual offshore winds. The largest seas will be over 
the outer waters for the next day or two, but a larger westerly 
swell looks to arrive midweek. This swell will push seas back to
7 or 8 feet, before seas again subside to 5 ft late in the
weekend.   Cullen


OR...Freeze Warning until 9 AM PDT this morning for Central 
     Willamette Valley-Lower Columbia-South Willamette Valley.

WA...Freeze Warning until 9 AM PDT this morning for Greater 
     Vancouver Area-I-5 Corridor in Cowlitz County.




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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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