A very potent atmospheric river brought strong winds to the north Oregon Coast and Coast Range on October 21st. What followed was a tremendous amount of rain for some locations along the north Oregon Coast and in the Coast Range, with Lees Camp receiving upwards of 9 inches of rain.
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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 very potent atmospheric river brought strong winds to the north Oregon Coast and Coast Range on October 21st. What followed was a tremendous amount of rain for some locations along the north Oregon Coast and in the Coast Range, with Lees Camp receiving upwards of 9 inches of rain. All this heavy rain brought the earliest significant Wilson River Flood on record, as well as flooding on several other rivers around the area.
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 Oct 21, 7:58 AM PST, 2 minutes earlier.
Area Forecast Discussion
National Weather Service Portland OR
858 AM PDT Sat Oct 21 2017
.SYNOPSIS...The first significant atmospheric river event of the
season is underway this morning across southwest Washington and
northwest Oregon. Rain will be heavy at times through Sunday morning
as a frontal zone stalls over the area. Portions of the Willamette
Valley may get a break in the heavier rainfall this afternoon and
evening as the frontal zone lifts slightly northward into Washington.
However the front will move back south across the forecast area
tonight and Sunday morning, bringing another round of heavy rain.
Strong winds will develop this afternoon and evening to the south of
the front. Showers decrease rapidly Sunday night as the front weakens
over SW Oregon. Drier weather is expected much of next week as high
pressure builds into the region, though a few showers are possible
Wednesday as a weak system clips by to our north.
&&
.SHORT TERM...Today through Monday...No changes. Previous discussion
is as follows: Classic atmospheric river event is underway across
southwest Washington and northwest Oregon. Strong isentropic lift
over an incoming warm front is producing widespread light to
moderate rain across the forecast area. Snow levels have already
risen to around 5000 feet and will continue to rise as warmer
subtropical air works its way into the region. The warm front will
push eastward across the Cascades today, but a baroclinic zone will
linger over the Pac NW through tonight. This frontal zone will serve
as a conduit for subtropical moisture, fed across the entire Pacific
from Japan by a strong jet stream, 150 kt+ at its core. Precipitable
water is certainly not lacking, with AMSU TPW showing a ribbon of
1.25 inch-plus stretching from the Oregon Coast all the way back
westward past the dateline. Meanwhile, the low-level jet is fairly
impressive to the south of the frontal zone, with 50 kt W-SW winds
at 850 mb. The result of this low-level jet will be impressive rain
rates and rainfall totals in the higher terrain due to orographic
enhancement. Latest Mesoscale Precipitation Discussion #0895 from
WPC mentions that rain rates in excess of 0.50 inch per hour are
possible in the higher terrain facing W-SW, and this certainly seems
reasonable once the warm front pushes through the forecast area.
Rainfall amounts will depend largely on how far northward into
Washington the frontal zone lifts today, as the heaviest rain and
strongest forcing will follow the front. Latest models have been
trending slightly farther northward with the front's progress, which
makes sense considering there really isn't anything to keep the front
from progressing northward at the moment. Eventually this front's
parent low will move into British Columbia this evening, putting some
southward pressure on the front. This will cause the front to slide
back southward late tonight and Sunday, pushing a round of heavy rain
southward across the forecast area.
Taking all this into account, southwest Washington and the north
Oregon Coast/Coast Range stand to see the heaviest rainfall from this
system at 4 to 8 inches. Rainfall will rack up quickly even south of
the front in the higher terrain, due to the favorable orographics.
However much of the Willamette Valley will probably get a break in
the heavier, steadier rainfall this afternoon and evening as the
front lifts north into WA. Adjusted our QPF downward in the
central/south Willamette Valley to account for this. Overall rainfall
from this system over the weekend will probably be in the 1.50 to
2.50 inch range for the Willamette and Hood River Valleys. With the
rain falling heavy at times in the Columbia Gorge due to the strong
W-SW low-level winds, the Eagle Creek burn scar area comes to mind as
a significant concern. Thus the Flash Flood Watch issued for that
area certainly seems justified. Burn scar areas further to the south
will need to be monitored as well. Areal flood watches remain in
effect for our forecast area roughly north of Salem, as smaller
rivers/drainages and urban flooding are a concern with the occasional
heavy rain.
Not to be outdone, winds will be impressive with this system as well,
especially inland. While the strongest south winds will be along the
coast, with gusts 60-70 mph possible, inland areas will be
susceptible to gusts in the 35-50 mph range once the warm front
passes this morning and southerly pressure gradients tighten. Models
are showing 45-60 kt just above the surface this afternoon and
evening, with good potential for mixing to the south of the frontal
zone. It will be windy in the Cascades as well, with good alignment
in the W-SW winds all the way up to the 90 kt winds at 500 mb per the
06z NAM. Some higher ridges may knock on the door of High Wind
Warning criteria late this afternoon into tonight, which is 50 mph
sustained and 75 mph gusts for the Cascades.
Models suggest the front will weaken quickly once it moves south of
the Lane/Douglas county line Sunday evening, as high pressure quickly
builds into the Pac NW. This will result in a quick drying trend
Sunday night, but there should be plenty of fog in the valleys due to
the abundant ground moisture. Monday looks at least partly sunny as
strong high pressure lingers, though fog may be a bit stubborn to
clear in portions of the Willamette Valley. Areas outside of
inversions have a decent chance to push into the 60s Monday as the
air mass warms aloft. Weagle
.LONG TERM...No Changes. Previous discussion follows...
Monday night through Thursday....Models are in agreement, that
shortwave ridging will develop over the Pacific NW early next week.
This will bring a period of dry weather. But, likely to see
considerable low clouds and fog Mon am and again Tue am. But, should
be very great fall weather, with dry and mild conditions for most
areas. Weak system will pass to our north later Tue night and Wed,
but will only put a small chance of showers for the region.
Afterwards, models agree that will get back into classic October
offshore flow, with mild days and cool nights. Rockey.
&&
.AVIATION...Overall flight conditions gradually deteriorating
this morning as a warm front spreads inland. Rainfall intensity
will steadily increase during the day, which will result in
general MVFR or worse flight conditions. Coastal sites likely to
become predominant IFR this afternoon and tonight. Strong
south wind will also develop along much of the Oregon Coast
with gusts up to 60 kt along exposed headland locations. KAST and
KONP can expect gusts up to 50 kt. There is also the potential
for LLWS in the Columbia Gorge and vicinity through at least the
afternoon hours. East wind will continue at the surface, but
model soundings and KTTD profiler data suggest SW wind 40-50 kt
at FL020.
KPDX AND APPROACHES...MVFR conditions as of 16Z and this should
be the primary category through 12Z Sun. SE wind to 15 kt will
shift to South 20 to 30 kt with gusts up to 40 kt this afternoon
and continue tonight. There is the potential for LLWS at the
terminal through early afternoon due to SE surface wind and SW
wind 40 to 50 kt at FL020. Weishaar
&&
.MARINE...Little change to current forecast. A strong warm front
has moved through the waters earlier this morning with a few
gusts up to 50 kt noted. Strongest wind this morning will be
generally within 20 to 30 nm, with coastal jet enhancement
likely. Latest guidance suggests wind speeds will diminish
slightly late this morning, but increase again during the
afternoon and evening. A few gusts to 50 kt will be possible
during this time frame. Current gale warning ends at 12Z, but may
need to extend it a little longer for PZZ255 and PZZ275.
Wind speeds drop off Sun, falling to 10 to 15 kt by early
afternoon. A wind shift from the East occurs Sun night and Mon
with speeds generally 10 kt or less.
Seas will be rather chaotic through tonight, with a large wind-
wave component. Overall wave heights will be 15 to 20 ft through
tonight. High surf advisory conditions not expected due to the
large wind-wave component. Wave heights ease to around 12 to 14
ft by Sun afternoon and then just under 10 ft Mon. Weishaar
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...Flash Flood Watch through Sunday afternoon for Central Columbia
River Gorge-Western Columbia River Gorge.
Flood Watch from noon PDT today through late Sunday night for
Central Willamette Valley-Coast Range of Northwest Oregon-
Greater Portland Metro Area-Lower Columbia-North Oregon
Coast-Northern Oregon Cascade Foothills-Northern Oregon
Cascades.
Wind Advisory from noon today to 4 AM PDT Sunday for Central
Willamette Valley-Greater Portland Metro Area-South
Willamette Valley.
High Wind Warning until 5 AM PDT Sunday for Central Oregon
Coast.
High Wind Warning from noon today to 5 AM PDT Sunday for
Central Coast Range of Western Oregon-Coast Range of
Northwest Oregon.
High Wind Warning...from noon today to 3 AM PDT Sunday for North
Oregon Coast.
WA...Flood Watch from noon PDT today through late Sunday night for
Central Columbia River Gorge-Greater Vancouver Area-I-5
Corridor in Cowlitz County-South Washington Cascade
Foothills-South Washington Cascades-South Washington Coast-
Western Columbia River Gorge-Willapa Hills.
Wind Advisory from noon today to 4 AM PDT Sunday for Greater
Vancouver Area.
High Wind Warning from noon today to 2 AM PDT Sunday for
Willapa Hills.
High Wind Warning from noon today to 11 PM PDT this evening for
South Washington Coast.
PZ...Gale Warning until 5 AM PDT Sunday for Coastal waters from Cape
Shoalwater WA to Cascade Head OR out 10 NM-Coastal waters
from Cascade Head to Florence OR out 10 NM-Waters from
Cape Shoalwater WA to Cascade Head OR from 10 to 60 NM-
Waters from Cascade Head to Florence OR from 10 to 60 NM.
Small Craft Advisory for Rough Columbia River Bar until 3 AM
PDT 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.The national radar mosaic for the moment the first event began.
5 flood, 4 high wind. Local standard time, as filed.
Had several reports of max wind gusts up to 58 to 63 mph. The highest reported gust was at a weather station at Gleneden Beach, which recorded peak gusts up to 63 mph.
A Oregon DOT weather station recorded sustained winds up to 53 mph on Megler Bridge.
The remote automated weather station at Rockhouse recorded wind gusts up to 78 mph.
Heavy rain, with amounts up to 10.7 inches in the Coast Range led to flooding on the Wilson River near Tillamook. The river crested at 17.05 feet, which is 5.05 feet above flood stage.
A Bonneville Power Association weather station on top of Mount Hebo recorded peak gusts up to 64 mph.
Heavy rain caused the Trask River near Tillamook to flood. The river crested at 17.56 feet, which is 1.06 feet above flood stage.
Heavy rain caused the Nehalem River near Foss to flood. The river crested at 15.02 feet, which is 0.02 foot above flood stage.
Heavy rain caused the Siletz River at Siletz to flood. The river crested at 19.07 feet, which is 3.07 feet above flood stage.
Heavy rain caused the Clackamas River near Estacada to flood. The river crested at 21.40 feet, which is 1.40 ft above flood stage.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Oregon in 2017Every state in 2017This day in weather historyWarnings in Oregon, October 2017
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: 724631, 724630, 724633, 724681, 724632, 724704, 724694, 724698, 724687.