High Wind and Strong Wind in Oregon, January 9, 2023

Area Forecast Discussion
National Weather Service Portland OR
344 AM PST Mon Jan 9 2023

.SYNOPSIS...Active weather continues through the upcoming week
as a series of strong low pressure systems develop and move
through the NE Pacific, pushing their occluding frontal systems
across NW Oregon and SW Washington. Expect mild, and
occasionally wet, breezy conditions throughout the week. Snow
levels will be near or below the Cascade passes through
midweek, then milder weather should lift snow levels above the
passes toward the end of the week.

&&

.SHORT TERM...THROUGH WEDNESDAY NIGHT...The parade of systems
continues over the NE Pacific early this morning as the latest
in a series of strong surface lows nears peak intensity of 967
mb approximately 400 miles west of Newport. An occluded front
extends south and eastward from the low center, with a secondary
triple point low taking shape off the southern Oregon Coast.
This secondary feature is poised to bring the next round of wind
and rain to the forecast area today, as latest model guidance
depicts the low center deepening to around 980 mb and tracking
rapidly northward this morning approximately 100 nm off of the
OR Coast, dragging a pair of frontal boundaries across the area
in rapid succession. Radar echos associated with the warm frontal
boundary are filling in over the southwest part of the state
and beginning to approach the south Willamette Valley as of 3
AM. Expect rain to continue to spread northward into the
Portland metro through the course of the Monday morning commute
as depicted by hi-res simulated reflectivity. Expect a
transition to showers for the remainder of the day as the
frontal system clears the Lower Columbia Valley by late morning.
All told, expect QPF amounts through this evening to range from
a tenth to a quarter of an inch in the interior valleys and a
quarter to a half inch along the coast in the higher terrain of
the Cascades. Can't rule out a few rumbles of thunder in the
coastal areas through this evening given modest, shallow
instability over the coastal waters. Snow levels remain around
4500 feet today, with only minor snow accumulations at best
expected through the Cascade passes.

Meanwhile, also expect winds to ramp back up later this morning
and shift from offshore to southerly as the low passes
offshore. Should see a similar result to yesterday, with 35-40
mph gusts in the Willamette Valley late morning to early
afternoon while coastal areas see gusts to 50 mph and perhaps
slightly higher on beaches and headlands. Winds on the coast
will be particularly sensitive to minor deviations in track and
intensity of the low, and with that in mind there is some
concern that wind gusts could briefly exceed 60 mph on the
central Oregon Coast early this afternoon, with NBM v4.1 probs
ticking upward to 30-50 percent in that timeframe. Ultimately
did not have the confidence for a High Wind Warning, but that
will be something to monitor through the day.

Tonight into Tuesday could bring somewhat of a lull in
conditions as another much weaker low looks to form off the
northern CA coast and tracks northward into the coastal waters.
This will maintain at least a slight chance of showers across
most of the area on Tuesday, but with QPF amounts generally
remaining around a tenth of an inch or less.

Wednesday will bring more substantial rain as another strong
surface low develops over the NE Pacific and drives a strong
front through the Pacific Northwest. QPF amounts with this
system currently ranging from a half inch in the valley to
around an inch in the coastal areas and the higher terrain, with
snow levels climbing well above the passes and limiting any
winter weather concerns. Can also expect another round of breezy
conditions with this frontal passage, although winds are
currently looking lower in magnitude than recent systems as the
low remains farther offshore. /CB

.LONG TERM...THURSDAY THROUGH SUNDAY...Active weather appears
likely to continue into the extended portion of the forecast as
large scale troughing over the NE Pacific maintains periods of
wet weather over the Pacific Northwest through the latter half
of the week. Guidance does continue to hint at some
amplification of the pattern for Thursday and Friday, resulting
in a shift in the jet stream over the north Pacific and at least
a temporary halting of the parade of systems tracking through
coastal waters. This would lessen any wind concerns through the
latter half of the work week, however WPC cluster analysis
continues to depict a quick return to a more zonal pattern
conducive to repeated offshore cyclogensis by the weekend. In
other words, expect periods of rain and wind to continue with
only brief breaks for the foreseeable future, although hydro and
winter weather concerns continue to appear minimal at this
time. /CB

&&

.AVIATION...12Z TAFs: Generally VFR across the area at 10Z.
However, local IFR fog was occurring, notably at KEUG and briefly
at KPDX. Expect whatever IFR or lower conditions develop early
this morning to be short-lived with increasing clouds and wind as
the next low pressure approaches the area. Expect precipitation to
develop over the southern part of the area early in the TAF
period, with areas of MVFR likely by 15Z. Offshore low-level flow
will keep the northern areas, especially areas near the west end
of the Gorge and south Washington and north Oregon coast, VFR
through at least mid to late morning. Increasing MVFR expected
into early afternoon. VFR conditions should become more
predominant mid to late afternoon and continue 12Z Tuesday.
Isolated IFR or lower conditions in fog will be possible between
06Z and 12Z Tuesday, mainly in the central and south interior
valleys.

Potential for low level wind shear through 18Z Monday, due to
increasing southerly winds aloft and gusty east winds near the
surface.

For detailed Pac NW aviation weather information, go online to:
http://weather.gov/zse

KPDX AND APPROACHES...VFR at the terminal and vicinity at 10Z,
with variable mid and high clouds. There have been brief periods
of IFR or lower conditions at KPDX and KVUO since 08Z, but not
anticipating those conditions to become more prevalent.
Precipitation expected to develop between 15Z and 18Z, with MVFR
likely into early afternoon. The KTTD-KDLS pressure difference
was -5.8 mb at 10Z and is forecast to peak at -8 mb Monday
morning. Expect 25-35 kt gusts at KTTD through the morning. The
gradient drops to around -1 mb Monday afternoon. Expect
southerly wind at the terminal, but the east wind at KTTD may
not completely go away. Potential for low level wind shear
Monday morning, due to increasing southerly winds aloft and
gusty east winds near the surface. Weishaar

&&

.MARINE...A series of low pressures will impact the coastal waters
over the next few days. Shortly before 2 AM, water vapor satellite
imagery revealed a strong surface low pressure center near 44N
133W. A second low center was noted 42N 127W. The latter feature
is forecast to shift a little more east through 5 AM and then race
north along 127W longitude. Gale force wind will develop over the
outer waters by 4 AM and continue through 10 PM Monday night. Peak
gusts to 40 kt can be expected. Gales shift to the inner zones by
mid Monday morning. The National Blend of Models (NBM) v4.0
gives close to an 80 percent chance of gale force gusts at buoy
46050. The v4.1 probability is close to 90 percent.

Wind speeds gradually settle down Monday evening and fall below 20
kt late Monday night. East to southeast wind to 20 kt prevails
Tuesday morning through through late afternoon. Gusts to 25 kt
likely downwind of coastal terrain gaps. Wind speeds ramp up
Wednesday morning as the next strong low pressure moves into the
eastern Pacific. Expect gale force conditions over the outer
waters Wednesday morning. A couple of models show 50-55 kt
boundary layer wind speeds brushing the far outer waters
Wednesday afternoon. The NBM v4.1 for buoy 46050 shows peak gusts
around 50 mph, with a 25 percent chance of storm force gusts. V4.0
shows little to no storm force likelihood. The EPS ensembles for
buoy 46050 show peak gusts 50-55 mph Wednesday night and Thursday
morning. All in all, solid gales look likely for the outer waters
Wednesday morning through Thursday evening.

At 1 AM, buoy observations indicated wave heights 13 to 16 ft.
Expect combined seas to peak near 20 ft Monday evening. There will
be a considerable wind wave component, with a background west
swell generally 7-9 ft. Wave heights ease to around 10 ft by
Tuesday evening. Wave model guidance continues to advertise wave
heights in excess of 25 ft Thursday. The highest waves will reside
over the outer water zones. The WCWave10 model shows peak combined
seas of 26-28 ft at buoy 46089 Thursday afternoon, with wave
heights closer to 20 ft for the inner zones. The NBM guidance is
similar, showing near 20 ft for the inner zones and up to 25 ft
in the far outer waters. Weishaar

&&

.BEACH HAZARDS...The predicted high-high tide for Toke Point
Monday afternoon is around 9.2 ft. However, the combination of
surge and anomaly is expected to produce an actual tide of 11.5
ft. This exceeds the 11.0 ft threshold for minor tidal overflow
issues along the south Washington coast. Will issue a Coastal
Flood Advisory due to minor tidal overflow for the south
Washington coast valid noon through 5 PM. Fortunately, river
levels are not exceedingly high. Weishaar

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...None.
WA...Coastal Flood Advisory from noon today to 5 PM PST this
     afternoon for South Washington Coast.

PZ...Hazardous Seas Warning until 10 AM PST this morning for coastal
     waters from Cape Shoalwater WA to Florence OR out 10
     nm. Columbia River Bar.

     Gale Warning from 10 AM this morning to 7 PM PST this evening
     for coastal waters from Cape Shoalwater WA to Florence OR
     out 10 nm. Columbia River Bar.

     Gale Warning until 10 PM PST this evening for coastal waters
     from Cape Shoalwater WA to Florence OR from 10 to 60 nm.

&&

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