Heavy snow associated with an atmospheric river fell in the Washington Cascades with 11 inches at Snoqualmie Pass and 8 inches at Hyak. Interstate 90 was closed from North Bend to Ellensburg for 3 hours due to multiple spin-outs.
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 PDT wrote it up.
Heavy snow associated with an atmospheric river fell in the Washington Cascades with 11 inches at Snoqualmie Pass and 8 inches at Hyak. Interstate 90 was closed from North Bend to Ellensburg for 3 hours due to multiple spin-outs.
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 Pendleton, OR wrote its last area forecast discussion before the first event at Dec 17, 8:27 PM PST, 3 minutes earlier.
Area Forecast Discussion
National Weather Service Pendleton OR
827 PM PST Mon Dec 17 2018
.SHORT TERM...Another busy night as the next strong Pacific warm
front with strong winds aloft pushes across Washington and Oregon.
Minor updates were made to the current forecast, mainly to
increase winds in a few locations and to decrease temperatures a
few degrees in the Kittitas and Yakima Valleys and the Blue
Mountains. No changes are expected in the current winter and wind
highlights. A close prognosis of the 12Z NAM12/ARW as well as the
HRRR runs indicate the potential for strong or potentially
damaging foehn winds across central and north central Oregon
tonight. A High Wind Warning is in effect for the east slopes of
the Oregon Cascades (zone 509) and Central Oregon (zone 511) where
a well-defined lee side trough will set up overnight. North
Central Oregon (zone 510) and the southern Blue Mountain Foothills
(zone 508) will likely observe gusts to 55 mph-- possibly stronger.
NAM12 indicates a 70 knot LLJ at 850mb, but the cross sections of
both the ARW and HRRR do not show the strong winds reaching the
surface. If any future runs indicate otherwise, the wind advisory
may be upgraded to a High Wind Warning. In addition, the Lower
Columbia Basin of Oregon (zone 44) may need a Wind Advisory. At
this time, the gusts to 45-50 mph will be on the far southern
portion of the zone affecting Ione. The Wind Advisory for the
Simcoe Highlands, the Oregon Blue Mountain Foothills (zones 507),
and the Grande Ronde Valley (zone 49) look reasonable. Other
locations that may have 45-55 mph gusts include Long Creek and
Joseph tonight through Tuesday morning.
Winter weather advisories are in effect for the northern Blue
Mountains above 4500 feet tonight. There will be a quick snowfall
accumulation of around 5-7 inches tonight before snow levels
increase to around 6000 feet.
Winds will taper off Tuesday night/Wednesday with weak ridging
ahead of the next wet and warm system Thursday afternoon. Another
surface lee side trough will set up over the west side of the Blue
Mountains for another round of strong winds in the Grande Ronde
Valley and the base of the Blue Mtn Foothills. Wister
&&
.PREV DISCUSSION... /issued 221 PM PST Mon Dec 17 2018/
LONG TERM...Thursday night through Monday...A progressive
weather pattern will persist through the long term period. A
series of Pacific storms will move through WA and OR bringing
periods of valley rain and mountain snow. A system will move
through Thursday night and start to clear out Friday morning. Some
snow showers will linger in the mountains Friday afternoon. Snow
levels will start out 4000-5000 ft Thursday evening and drop to
1000-2500 by Friday afternoon. Some snow will accumulate in the
mountains with the greatest amounts over the higher elevation of
the Washington Cascades. Gusty winds will occur with the front
over the higher terrain and foothills of the Blue Mountains. A
weak ridge will move over WA and OR Friday night. Saturday a
dissipating system will move through the ridge producing clouds
and some mountain showers. Ensemble models start to diverge
significantly in timing and strength Sunday when an occluded low
moves through WA or southern Canada followed by a stronger low
moving along the through WA/OR border (GFS) or northern CA (ECMWF)
Monday. These lows will bring much colder air into the area with
snow level falling to 500 feet along the east slopes of the
Washington Cascades to 3000 feet over central Oregon and near 1500
feet over northeast Oregon. Strong and gusty winds will develop
Sunday and Monday over higher terrain and in the Grande Ronde
Valley ahead of these systems. Coonfield
AVIATION...0z TAFs...Fog and low stratus will continue to
impact KYKM and KDLS break up this evening as a front moves into the
area. Winds will increase this afternoon through tonight, when
strong and gusty south winds develop ahead of a storm system. The
strongest winds near a taf site will be at KBDN. Rain will develop
this evening over KDLS and KYKM, and then spread to most terminals
by the end of the period. KPDT and KALW will not have more than
occasional sprinkles until winds shift SW after 15Z. 76
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 42 54 39 51 / 80 60 50 10
ALW 46 54 41 51 / 100 60 60 10
PSC 43 55 41 51 / 80 60 10 10
YKM 34 49 32 46 / 60 70 60 10
HRI 41 56 40 52 / 80 60 20 10
ELN 33 45 33 44 / 80 90 60 10
RDM 42 53 32 50 / 30 70 50 10
LGD 36 44 37 43 / 100 90 70 10
GCD 37 46 34 43 / 70 70 40 10
DLS 39 50 38 48 / 90 90 70 20
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Wind Advisory until 3 PM PST Tuesday for ORZ507-508-510.
Winter Weather Advisory until 10 AM PST Tuesday for ORZ502.
High Wind Warning until 3 PM PST Tuesday for ORZ509-511.
Wind Advisory from 1 AM to 3 PM PST Tuesday for ORZ049.
WA...Wind Advisory until 3 PM PST Tuesday for WAZ521.
Winter Weather Advisory until 10 AM PST Tuesday for WAZ030.
&&
85/1 heavy snow. Local standard time, as filed.
Eleven inches of snow fell at Snoqualmie Pass. Interstate 90 was closed for 3 hours due to multiple spin-outs on the pass.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Washington in 2018Every state in 2018This day in weather historyWarnings in Washington, 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: 790201.