NWS Portland, OR wrote its last area forecast discussion before the first event at Feb 9, 2:13 AM PST, 2 hours 32 minutes earlier.
Area forecast discussion, Feb 9, 2:13 AM PST, 2 hours 32 minutes before
Area Forecast Discussion
National Weather Service Portland OR
213 AM PST Thu Feb 9 2017
.SYNOPSIS...A very moist frontal boundary will slowly move inland
late tonight and Thursday. Offshore low-level flow will persist
through Thursday, which will maintain cold air in the Columbia
Gorge, Hood River Valley and parts of east Skamania County in SW
Washington. Significant ice and snow can be expected in these areas
through Tomorrow until the attendant cold front crosses in the
afternoon. A secondary trough swings into the area late tomorrow
night and Friday morning, which could result in a second round of
high wind along the coast. Unsettled conditions continue through
Saturday. High pressure finally returns late Saturday and Sunday and
will hold through the first part of next week.
&&
.SHORT TERM...Today through Saturday...Still a pool of cold air over
the Hood River Valley this morning with temps at or below freezing
all the way from Columbia River level up past Middle Mountain at
2500 feet. Temps overall though have been rising overnight, as a
surface warm front has lifted north up the coast, and into the North
Willamette Valley by 2 am. Even north of the front the low level
cool air has been eaten away from the top, with places like the West
Hills and Yacolt topping 50 deg. Warm front has also ushered in some
gusty winds, esp along the coast and at high elevations in the Coast
Range. With the warm front through along the coast, expect the next
big push of wind to accompany the cold front later this morning.
Given the winds that accompanied the warm front brought some strong
winds to the inland coastal communities, will reword the coastal
high wind warning to include entire coastal strip. The high winds in
the Coast Range have generally been higher isolated peaks, so will
refrain for any headlines there. As offshore gradients do not really
weaken substantially until the cold front moves through later this
morning, and any onshore gradients behind the front looks weak,
prefer to hang onto the winter storm warning in the Central Gorge,
Upper Hood River Valley, and the South WA Cascades today, although
am becoming optimistic that mixing erosion of cold dome from the top
down may end freezing rain a little earlier than currently forecast.
In the west Gorge, temps have already moderated to freezing or a
little above. Any further icing there looks short lived at best as
temps contine to moderate, so will drop the warning there.
The unreasonably warm temps south of the warm front this morning
will not last all day, as a cold front pushes through the forecast
area later this morning, moderating temps a bit for the afternoon
with a more seasonable Pacific air mass. Air mass this afternoon
becomes more showery in nature, as model forecast soundings indicate
decent amount of instability. A low level southwest flow will favor
SW facing terrain with orographic lift for most persistent showers.
The showery unstable air mass continues through Friday as several
short waves move across. Air mas begins to stabilize with ridging
aloft Fri night into Sat, but an increasingly shallow, and
marginally unstable air mass continues to be depicted by models into
Sat. Will indicate diminishing pops with time, but still need to
include some low pops across the north through Sat for light
showers. On Friday a compact low crosses the southern part of
Vancouver Island, enhancing pressure gradients down the WA coast.
Expect gusty winds in the morning along the south WA coast as the
surface trough moves inland, but does not look like there is much
opportunity to enahce winds with a coast jet due to the more
westerly orientation to surface winds.
.LONG TERM...Saturday Night through Wednesday...Upper level ridging
moves in for the first half of the long term period which will usher
in a period of quiet, dry weather into the beginning of next week.
ECMWF and GEM keep weather dry into Wednesday morning, however the
GFS brings a shot of rain into the area Monday Night/Tuesday. All 3
models are consistent cutting off an upper low underneath the ridge
and swinging it through on Tuesday, but the GFS brings better
moisture with it and actually pushes the wave inland. Have added
slight chance PoPs to the Monday night/Tuesday timeframe, but most
likely solution is still the dry ECMWF/GEM. Otherwise, freezing
levels look like they will push up to the 7000 to 9000 ft range
towards the middle of next week which won't be great for ski
resorts, although it is possible the Portland area could see its
first week with multiple 50 degree days since November. /Bentley
&&
.AVIATION...at 2 am, a warm front, which extends from KHQM to
south side of KPDX to north of KRDM, will push into Washington
by 14Z. This will allow conditions to becoming a mix of VFR and
MVFR, with rain continuing. A cold front will move onshore around
18Z, with rain becoming more showery. Other issue is moderate to
strong southerly flow across the region, especially along the
coast and just above surface over the interior. This flow will
gradually ease this afternoon.
KPDX AND APPROACHES...Mix of VFR and MVFR this am, with quick
shift to southerly winds between 3 am and 5 am, but will maintain
wind shear in the TAF until 14Z in case east winds hold longer
than expected. Still think will see return of MVFR with rain
between 15z and 18z as cold front approaches. Front will push
across OPS area 18Z to 19Z, with transition back to a VFR with
occasional MVFR/showers. Rockey.
&&
.MARINE...Warm southerly flow on the coastal waters early this
am, with winds gusting 40 to 50 kt, with strongest winds over the
Oregon waters. Cold front will push onshore between 9 and 10 am,
with winds easing to 25 to 30 kt. Will maintain Storm Warning
until mid-morning, then will likely need to put up Gale Warning
for rest of today. Seas have been building quickly, and currently
around 15 to 17 ft. Still think seas will peak at 20 to 23 ft
around daybreak today, then will gradually subside as winds drop
back today.
The parent low pres responsible for this active weather will
swing eastward towards the PacNW early Fri and likely bring
another round of stronger winds...generally in the 35 to 40 kt
range, with seas back int 15 to 20 ft range.
High pres should then build across the waters Saturday through
at least Monday, which will bring substantially quieter weather
and seas to the waters. However, an active weather pattern looks
to resume towards the middle of next week. /Neurockpyle
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...Winter Storm Warning until 4 PM today for...
Central Columbia River Gorge
Upper Hood River Valley.
Ice Storm Warning until 10 AM today for...
Western Columbia River Gorge.
Flood Watch through late Friday night for much of northwest
Oregon.
High Wind Warning until 10 AM today for...
North Oregon Coast
Coast of West Central Oregon.
Coastal Flood Advisory from 9 am to 2 pm today for...
North Oregon Coast.
WA...Winter Storm Warning until 4 PM today for...
Central Columbia River Gorge
South Washington Cascades.
Ice Storm Warning until 10 AM today for...
Western Columbia River Gorge.
Flood Watch through late Friday night for much of
southwestern Washington.
High Wind Warning until 10 AM today for...
South Washington Coast.
Coastal Flood Advisory from 9 AM to 2 PM PST today for...
South Washington Coast.
PZ...Storm Warning until 10 AM today on all Coastal Waters.
Small Craft Advisory for Rough Columbia River Bar
conditions today through 7 am Fri.
&&
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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.