A strong low pressure system over the Gulf of Alaska brought a strong cold front through. This generated strong winds across northwest Oregon, and also brought heavy rain which caused flooding on the Tillamook river.
Every event with a place to put it. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS PQR wrote it up.
A strong low pressure system over the Gulf of Alaska brought a strong cold front through. This generated strong winds across northwest Oregon, and also brought heavy rain which caused flooding on the Tillamook river. Large seas also caused damage in spots along beaches.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Portland, OR wrote its last area forecast discussion before the first event at Dec 17, 3:34 PM PST, 1 hour 26 minutes earlier.
Area Forecast Discussion
National Weather Service Portland OR
334 PM PST Mon Dec 17 2018
.SYNOPSIS...A developing atmospheric river event will bring heavy
rain Monday evening into Tuesday. Strong south winds will develop
along the coast Monday afternoon, then spread inland this evening and
tonight. The strongest winds and heaviest rain will occur overnight
and into Tuesday morning. Active weather will continue through the
end of the week, with another frontal system expected to bring more
rain and gusty winds Thursday.
&&
.SHORT TERM...This afternoon through Thursday night...Plenty of
impactful weather expected, especially in the next 24 hours, but
there aren't that many actual forecast updates. Let's start with the
immediate threat of high surf along area beaches. Although wave
heights are a bit lower than initially thought, the threat for high
surf will remain through Tuesday morning. In combination with other
factors to be talked about below, it is recommended that people stay
off the beaches due to the increased likelihood of significant runup
of water on the beach, which can knock bystanders over and
potentially sweep them out to seas. Seas will decrease some on
Tuesday, at least temporarily ending the threat.
A fairly strong Atmospheric River remains on track to bring a long
period of moderate rainfall with embedded periods of heavy rainfall
to the entire local forecast area late this afternoon through Tuesday
morning. Upped rainfall forecast this morning and those changes still
appear to be on track with more rain expected north and a little bit
less rain, but still significant amounts, expected south. A Flood
Watch remains in effect for a large portion of the local area
starting tonight, addressing both river flooding as well as an
increased threat of significant urban flooding in the Northern
Willamette Valley and Portland Metro Area. If significant urban
flooding occurs, it would be most likely to begin between 4 AM and 10
AM Tuesday, potentially affecting the Tuesday morning commute in the
Portland Metro Area. The biggest question with this heavy rain will
be when and how quickly a front moves through from northwest to
southeast tonight/Tuesday morning. Right now it look like the front
will hang up near the Oregon/Washington border, thus creating the
heavy rain needed for urban flooding. However, if the front moves
through more cleanly/quickly or hangs up further north or south, the
impacts will be different.
Along with lots of rain, this system will also bring wind, likely the
most wind lots of places have seen so far this season. Pressure
gradients along the coast are initially oriented rather offshore
this afternoon, but gradually open up late this afternoon into
this evening. This should allow high winds to surface along the
coast including the coastal communities and eventually into the Coast
Range as well. Model soundings appear to favor good mixing, such that
winds up to 850 mb may mix down to the surface as the coast and in
the Coast Range, translating to gusts to 80 mph for beaches and
headlands, and as high as 75 mph for coastal communities and the
higher elevations of the Coast Range. A High Wind Warning remains in
effect for those areas.
Wind will also impact the Willamette Valley. It continues to look
like the strongest winds will be in the central and south valley
areas, but also on exposed higher hills. Mixing isn't nearly as good
in the valley as at the coast, so expect wind speeds to be more
limited, but still the highest seen so far this season. Because there
hasn't been a significant wind storm yet for much of the valley,
could see a few more trees down than we'd usually see with gusts to
50 mph. The north Willamette Valley will serve as the transition
zone between strong winds and just breezy conditions, so some
portions of the north valley will also see gusty winds tonight and
possibly into Tuesday morning. A Wind Advisory remains in effect for
the Willamette Valley north to the Columbia River.
Snowfall usually isn't a concern with Atmospheric Rivers as they
bring warm air. However, cool air leftover in eastern Skamania County
may result in a brief period of heavy snow there this
evening before snow levels quickly rise with the arrival of the
deeper subtropical air mass. The snow level in this area looks to
start out around 3000-4000 feet, but quickly rises to well above 5000
feet overnight. Given the brief nature of this burst of snow and the
fact that it will mainly impact wilderness areas, will not issue any
winter weather hazards. Otherwise, snow levels will remain well above
the passes and likely most of the ski resorts during the bulk of this
event, as expected during these types of events.
Rain will taper to showers behind the front, with cooler air lowering
snow levels closer to the Cascade Passes by Wednesday morning. Models
do show some potential for convection in the cooler air mass behind
the front Tuesday. NAM lifted indices have decreases to just under 0
deg C, but will see if that trend holds before adding any thunder to
the forecast. Air mass stabilizes Tuesday night into Wednesday
morning as the frontal zone begins to lift northward as a much weaker
warm front that is only likely to produce light rain. Bowen
Rain showers will end Wednesday as an upper level ridge builds over
the Pacific NW. The next approaching warm front should stay offshore
Wednesday afternoon and evening, and move north of the Portland
forecast area before moving inland. Therefore expect mostly dry
weather Wednesday afternoon and night. The models vary on how strong
the upper ridge will be and how long the trailing cold front will
stall offshore before moving inland, but generally agree that rain
will reach the coast Thursday morning, the Willamette Valley early
Thursday afternoon, and the Cascades late Thursday afternoon.
Currently expect rainfall totals around 0.75 inch for the coast,
coast range and the Cascades Thursday morning through Thursday night,
and around 0.5 inch of rain for the interior valleys. Snow levels
will be above the Cascade passes through Thursday evening, then lower
behind the front late Thursday night as the rain turns to showers and
decreases. ~TJ
.LONG TERM...Friday through Monday...Friday high pressure builds
over the area as we sit between systems. Models are not in great
agreement for Saturday, as the GFS keeps us dry while the ECMWF has
another weak system move through Saturday. Models are in better
agreement on the next system Saturday night into Sunday. Back-to-
back systems will bring another round of precipitation on Monday.
Snow levels will be lower for the possible system on Saturday, down
around 1800 to 2500 feet. The following system on Sunday lifts snow
levels up to around 4000 to 5000 feet, and stays around 4000 to 5000
feet through the Monday system as well. -McCoy
&&
.AVIATION...VFR conditions will give way to widespread MVFR
conditions between 06-18z Tuesday. There will likely be periods
of IFR conditions along the coast as well. In addition, a band of
heavy rain associated with a cold front will likely push
southeastward through the Willamette Valley between 12-18z
Tuesday, which will likely bring a period of IFR conditions
inland as well. It should also be noted that strong southerly
winds will develop along the coast with gusts of 50-55kt possible
at the coastal taf sites between 06-12z Tuesday. In addition,
breezy southerly wind gusts may also develop in the Willamette
Valley, but confidence is lower that these will materialize. If
these don't then low level wind shear will become problematic at
many terminals in the Willamette Valley.
PDX AND APPROACHES...Expect VFR conditions today to give way to
an extended period of MVFR conditions late tonight and Tuesday
morning. An intense band of rain lasting less than an hour will
likely move through between 12z and 18z Tuesday, which will
likely create a period of IFR conditions. In addition, increasing
southerly winds over the terminal will create low level wind
shear over the terminal in the meantime. /Neuman
&&
.MARINE...Southerly winds generally 15 to 25 kt this am, with
seas running at 20 to 22 ft. But, that will change today, as yet
another strong frontal system pushes into the region.
A strong frontal system is continuing to advance closer to the
Pacific Northwest this afternoon. High end gales have already
developed across the coastal waters, and the Storm Warning is now
in effect and looks on track. These strongest winds will be over
the Oregon coastal waters between 7 PM and 3 AM with peak
gusts around 55 kt. Winds will ease from north to south Tuesday
morning, but gusts around 30 kt will likely continue into Tuesday
afternoon and evening.
Seas have been a bit slower to come up, with a decaying large
westerly swell still influencing the waters, but the wind driven
seas have yet to develop resulting in this lower in between time.
As a result, have slightly lowered the overall wave heights
closer to 25-27 feet, with perhaps portions of the southern
coastal zones seeing seas around 30 feet at the peak.
Looking ahead, expect a brief lull in between systems for about
24 hours late Tuesday night into Wednesday evening, but the next
front will arrive in the outer coastal waters late Wednesday
night. Forecast models diverge a bit, but regardless expect seas
to again build to 20 feet, perhaps up to 25 feet, and possible
southerly gales by early Thursday. Cullen
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...Flood Watch from midnight PST tonight through Wednesday
afternoon for Central Coast Range of Western Oregon-
Central Oregon Coast-Central Willamette Valley-Coast Range
of Northwest Oregon-Greater Portland Metro Area-Lower
Columbia-North Oregon Coast-Northern Oregon Cascade
Foothills-Upper Hood River Valley.
Flood Watch from late tonight through Wednesday afternoon for
Central Columbia River Gorge-Western Columbia River Gorge.
High Wind Warning until 6 AM PST Tuesday for Coast Range of
Northwest Oregon-North Oregon Coast.
High Surf Warning until 6 AM PST Tuesday for Central Oregon
Coast-North Oregon Coast.
High Wind Warning until noon PST Tuesday for Central Coast
Range of Western Oregon-Central Oregon Coast.
Wind Advisory until noon PST Tuesday for Central Willamette
Valley-South Willamette Valley.
Wind Advisory until 8 AM PST Tuesday for Greater Portland Metro
Area.
WA...Flood Watch from midnight PST tonight through Wednesday
afternoon for Central Columbia River Gorge-Greater
Vancouver Area-I-5 Corridor in Cowlitz County-South
Washington Cascade Foothills-South Washington Coast-
Western Columbia River Gorge-Willapa Hills.
High Wind Warning until 6 AM PST Tuesday for South Washington
Coast-Willapa Hills.
High Surf Warning until 6 AM PST Tuesday for South Washington
Coast.
PZ...Storm Warning until 5 AM PST Tuesday for Coastal Waters from
Cape Shoalwater WA to Cascade Head OR out 60 NM.
Storm Warning until 10 AM PST Tuesday for Coastal Waters from
Cascade Head OR to Florence OR out 60 NM.
Small Craft Advisory for Rough Columbia River Bar until 6 PM
PST Tuesday.
&&
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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.The national radar mosaic for the moment the first event began.
4 high wind, 2 strong wind, 1 high surf, 1 flood. Local standard time, as filed.
A trained spotter sent in pictures of damage from two beachfront buildings. One looks like the beach eroded beneath the decking, which has caused the decking to sag. The other looks like waves crashed into the bottom floor causing the wall to be pushed inward.
A weather station on Megler Bridge recorded wind gusts up to 65 mph. Winds also caused power outages impacting 209 customers in Warrenton, according to Pacific Power.
Oregon Department of Transportation reported trees down on Highway 6 and Highway 18 through the Coast Range. A weather station on top of Mt Hebo recorded wind gusts up to 85 mph.
Rockhouse RAWS recorded wind gusts up to 63 mph. Pacific Power reported an outage affecting 167 customers. A storm spotter in Swiss Home reported that two trees were uprooted by the winds, there were many trees and branches down, and the power was out.
Weather stations along the central Oregon coast reported wind gusts up to 55 to 70 mph. Highest recorded was on the Yaquina Bridge, which recorded wind gusts up to 79 mph. There were widespread power outages in Depoe Bay and Lincoln City. ODOT reported trees down on Highway 101, Highway 229, and Route 34 at milepost 5.5.
A large oak tree fell on a house 2 miles NW of McMinnville. The McMinnville ASOS recorded wind gusts up to 45 mph. There were several power outages. A section of a fence was blown over 3 miles WNW of Salem.
Several power outages were reported by PGE. Peak wind gusts of 35 to 43 mph were recorded across the Portland Metro and north Willamette Valley.
The Wilson River near Tillamook crested at 12.5 feet around 10 AM, which is 0.5 foot abouve flood stage. No damage was reported.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Oregon in 2018Every state in 2018This day in weather historyWarnings in Oregon, December 2018
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 799105, 799016, 799073, 799074, 799072, 799077, 799078, 799085.