560 
FXUS66 KPQR 161718 AAB
AFDPQR

Area Forecast Discussion...Update 
National Weather Service Portland OR 
918 AM PST Sat Feb 16 2019

Updated Aviation section

.SYNOPSIS...A series of lows will continue cool and showery weather
through tonight. Mostly dry weather is expected Sunday and Monday as
an upper ridge moves over the pacific NW. Light and brief showers are
possible Monday night before an upper trough brings a better chance
for rain and Cascade snow Tuesday and Wednesday. Snow levels will
remain rather low, but they should generally remain above the valley
floors except in the Columbia Gorge and Hood River Valley.

&&

.UPDATE...Low pressure moved onshore in pieces overnight, with the
northern circulation center moving right across the western and
central Columbia River Gorge and Hood River Valley. As a result, snow
spread across Hood River beginning around 5 AM and was briefly heavy.
Spotter and public reports suggest a quick 2 to 4 inches of snow fell
across Hood River, resulting in snowy and icy roads along I-84,
WA-14, and OR-35. Decided to handle this with a Special Weather
Statement, as the back edge of the steadier snow appeared to be
moving across the Hood River Valley while the remnant low pressure
circulation exits into north-central Oregon. Reports over the past
10-20 minutes appear to confirm this is the case. Temperatures should
rise above freezing shortly below 500-1000 feet in elevation, so road
surfaces should improve soon. Snow showers this afternoon should mix
with rain below 500-1000 feet as temps rise above freezing. Updated
the grids and zones accordingly.  Weagle

.SHORT TERM...Today through Monday night...A low pressure system is
moving across NW Oregon early this morning continuing showers over
the area. Snow levels are generally between 1500 and 2000 feet, but
are locally lower in the central Columbia Gorge and Upper Hood River
Valley. The low will move east of the Cascades by noon today, but
another low follows close behind and will continue showers this
afternoon and evening. The second low should remain offshore as it
slides south along the Washington and Oregon coast tonight into
Sunday morning with showers decreasing from north to south behind the
low. Although there will not be continuous snow in the Cascades
through Saturday evening, there will be enough snow above 1500 feet
in the Oregon Cascades and Foothills to warrant a Winter Weather
Advisory through Saturday evening. Have extended the Winter Weather
Advisory to include the north Oregon Cascades. Snow showers are
likely in the central Columbia Gorge and Upper Hood River Valley
where cold air has remained trapped in the lower levels, but do not
expect significant accumulations.  

An upper level ridge builds over British Columbia Sunday and Monday
pushing the upper trough southward for drier conditions. Temperatures
will be in the 20s Sunday night into early Monday due to radiation
cooling and light offshore winds developing in the Columbia Gorge.
Brief showers are possible late Monday night and Tuesday as an upper
level trough moves north to south offshore the Washington and Oregon
coast. The models are not in good agreement on the strength of this
low or how far offshore it will be so forecast	confidence is low on
the details of the showers. Currently the models agree that any
showers will be light and brief. Snow levels will be low , around
1000 feet, and currently think the best chance for snow is a light
dusting for the Oregon coastal mountains. ~TJ

.LONG TERM...No Changes. Previous discussion follows...Tuesday
through Friday...A shortwave trough slides down into the area,
resulting in precipitation and slightly cooler temperatures Tuesday
into Wednesday. Both models show a low pressure system entering the
area Wednesday night into Thursday, bringing higher chances of
precipitation and lowering snow levels to around 500 to 1000 ft. Even
though snow levels are lowering, 850 mb temperatures will remain
around -6C to -5C. These 850 mb temperatures along with onshore flow,
typically don't signal snow down to the valley floor. A shortwave
ridge quickly moves across the area Thursday night resulting in a
brief dry period before the next Gulf of Alaska low moves through
next weekend. /Thaler/42

&&

.AVIATION...A surface low is moving onshore along the north
Oregon coast this morning, maintaining showers and predominantly 
MVFR conditions, with some localized IFR as well. Expect little 
change through the day as the low slowly moves northeast through the 
region. Another low will drop south along the coast later today and 
tonight, continuing the shower threat. Showers will begin to taper 
off from north to the south overnight as the low passes. Expect 
conditions to gradually improve to VFR during the evening. Mountains 
of the Cascades, and possibly the Coast Range will remain obscured 
in clouds/rain through much of the period.

KPDX AND APPROACHES...Expect mainly MVFR conditions with periodic 
showers through this evening. Showers should taper off later in the 
evening, with conditions improving to mainly VFR. Cullen

&&

.MARINE...Surface low pressure is moving onshore this morning. NW
winds are picking up behind the low, with gusts of 25 to 30 kt. 
The winds will gradually subside through the day as the low 
pushes further onshore and weakens. Expect winds to be generally 
20 kt or less by late afternoon or early evening. Another low 
will drop south from Vancouver Island and move directly over the 
waters tonight into early Sun. This should keep winds fairly 
light during this time. High pressure builds over the waters 
early next week. However, weak lows will move periodically 
through from the NW. The strongest system looks to be later Tue 
into Wed. This one brings the potential for small craft advisory 
winds, or potentially even gales. 

Seas remain in the mid teens this morning and will be fairly
steady through the day. They should gradually subside tonight and
Sunday, dropping below 10 ft by Sunday afternoon. The Tue
night/Wed system may bring the potential for seas into the upper
teens, or potential even above 20 ft. Pyle

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...Winter Weather Advisory until 11 PM PST this evening for 
     Cascade Foothills in Lane County-Cascades in Lane County-
     Northern Oregon Cascade Foothills-Northern Oregon Cascades.

WA...None.

PZ...Small Craft Advisory for winds until 4 PM PST this afternoon 
     for Coastal Waters from Cape Shoalwater WA to Florence OR 
     out 60 NM.

     Small Craft Advisory for hazardous seas until 10 AM PST Sunday 
     for Coastal Waters from Cape Shoalwater WA to Florence OR 
     out 60 NM.

     Small Craft Advisory for Rough Columbia River Bar until 5 PM 
     PST this afternoon.

     Small Craft Advisory for Rough Columbia River Bar from 1 AM to 
     4 AM PST Sunday.

&&

$$

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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.