Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 181035
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
334 AM PDT Wed Oct 18 2017

.SYNOPSIS...A series of progressively moister fronts bring a
prolonged period of wet weather through next weekend. Breezy
conditions are expected Today and Thursday as well as periods of
heavy rain. Snow levels will lower to near the Cascade passes Friday
and Saturday. A ridge building in early next week may dry us out for
a period of mild, dry weather.

&&

.SHORT TERM...Today through Friday...We are currently in a break
between systems, but the next round can be seen on radar off the
coast of Washington.  Rain will make it to the north Oregon south
Washington coast this morning, but inland may stay mostly dry,
especially in Oregon, with a bit higher chance of precipitation in
inland Washington. Models show a breezy day in store for today, with
the strongest winds in along beaches and headlands north of Cascade
Head, and in the Willapa Hills and north Oregon Coast Range.  Have
upgraded the High Wind Watches to High Wind Warnings to reflect
increasing confidence in winds up to 60 mph today.

This evening, expect the trailing cold front to start to creep
southeastward into our area, bringing substantial rain across our
forecast area tonight through Thursday.  The high amount of available
moisture provides greater confidence that rain will be heavy at
times. This cold front stalls as it moves across our area, bringing
heavy rain on and off through the day on Thursday. An additional 1 to
3 inches of rain is possible for the higher terrain of SW Washington
and north Oregon Wednesday night through Thursday evening. Other
areas (including Lane County) can expect 0.75 to 1.5 inch of rain.
The cold front will also bring a period of gusty winds to the region.
The winds will not be as strong as Wednesday but will become
noticeable in most areas.

The trailing upper-level trough will continue showers Thursday night
into Friday behind the cold front. These showers will be more
unstable Thursday night into early Friday along the coast, with the
possibility for a thunderstorm or two over the coastal waters or
along our coastline. Snow levels will be lower, near the Cascade
passes as well Thursday night into Friday. The higher cascades could
see 4 to 8 inches of new snow Thursday night through Friday
afternoon. Localized spots near the passes could see 1 to 3 inches
of snow.Those travelling through the Cascades on Friday should be
prepared to encounter some snow on the passes. -McCoy


.LONG TERM...Friday night through Tuesday....Snow levels will start
to rise as Saturday approaches. Another frontal system will start to
pass through the region on Saturday, which has the potential to bring
another round of significant rain into the area, possibly even more
than we see with the system on Thursday. Expect gusty winds
especially along the coast and in the higher terrain of the Coast
Range through Saturday.  Models show this system stalling over our
area, with the trailing cold front not moving through until as late
as Sunday evening or early Monday. Timing and location of heaviest
rainfall may continue to change with future updates, so those with
plans this weekend should keep an eye on the forecast as this weekend
approaches.

Going into early next week, upper-level ridging starts to build into
the Pacific Northwest, bringing us an extended break in the rain.
Temperatures climb back up into the 60s as well, but because of all
the recent rain temperatures will be hampered by morning fog. Expect
dry weather to continue through Tuesday. -McCoy

&&

.AVIATION...MVFR stratus predominant flight conditions early this
morning. IFR fog has diminished as overrunning clouds from
approaching warm moves in to the area. There is also a little
more wind. IFR cigs or fog may still continue for the next
several hours however.

A warm front lifting across our northern sites Wednesday morning
should result in more persistent IFR and MVFR conditions as
light rain spreads across the area. The warm front lifts north of
TAF site late morning and increasing southerly winds should bring
MVFR to VFR conditions across the area inland. Coastal areas
will probably be mostly MVFR all day.

KPDX AND APPROACHES...MVFR is expected to be the predominant
flight category through this morning. However there`s still a
possibility of IFR conditions in the area early this morning and
with rain associated with a warm front later this morning. Should
see a trend to VFR by late morning or early afternoon as the warm
front lifts north of the area. Additionally, south winds
increase around 18z with gusts pushing 25 kt at times in the
afternoon. /mh

&&

.MARINE...A warm front will lift northeastward across the
northern waters this morning to bring Gale Force southerly wind
gusts of 35 to 40 kt into the northern waters in morning before
gradually filling in across the central Oregon waters later in
the day. A trailing cold front will then drop southeastward and
bring an end to the Gale Force winds late this evening across
the northern waters and towards daybreak on Thursday across the
central Oregon waters. In addition, coastal jet development will
likely produce locally stronger wind gusts of 45 kt within 10 nm
of the coast. Either way, the strong winds should allow seas to
climb into at least the mid teens across the waters.

Winds will likely drop into low end Small Craft Advisory criteria
behind the front, which should allow seas to drop into the low
teens early Thursday. However, this decrease in the seas will
likely be short lived as a large westerly swell of 20 to 22 ft
with periods of 15 to 17 seconds appears likely to impact the
waters beginning midday Thursday. High Surf Advisories will
likely be needed. An additional storm system capable of producing
at least Gale Force wind gusts appears on track for either late
Friday or Saturday as well. /mh /Neuman

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...High Wind Warning from noon today to 11 PM PDT this evening for
     Coast Range of Northwest Oregon-North Oregon Coast.

WA...High Wind Warning from noon today to 11 PM PDT this evening for
     South Washington Coast-Willapa Hills.

PZ...Gale Warning until 11 PM PDT this evening for Coastal waters
     from Cape Shoalwater WA to Cascade Head OR out 10 NM-
     Waters from Cape Shoalwater WA to Cascade Head OR from 10
     to 60 NM.

     Gale Warning from 2 PM this afternoon to 9 AM PDT Thursday for
     Coastal waters from Cascade Head to Florence OR out 10 NM-
     Waters from Cascade Head to Florence OR from 10 to 60 NM.

     Small Craft Advisory for Rough Columbia River Bar until 6 AM
     PDT early this morning.

     Small Craft Advisory for Rough Columbia River Bar from 2 PM
     this afternoon to 3 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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