North flow behind a modified Arctic cold front caused significant snow across northwest and north facing slopes in north-central and northeast Oregon. Also locally significant snow fell in portions of southeast Washington.
Every event with a place to put it; 5 filed by county or forecast zone are drawn at its center, in a lighter ring. 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 PDT wrote it up.
North flow behind a modified Arctic cold front caused significant snow across northwest and north facing slopes in north-central and northeast Oregon. Also locally significant snow fell in portions of southeast Washington.
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 22, 9:53 AM PST, 2 hours 21 minutes earlier.
Area Forecast Discussion...Updated
National Weather Service Pendleton OR
953 AM PST Fri Dec 22 2017
Updated Aviation Discussion
.UPDATE...A cold front sagging south across Washington and
northern Oregon today will bring areas of snow to all elevations
through Saturday morning. Elevations below 1500 feet in eastern
Washington and northeast Oregon and below 3000 feet in central and
north central Oregon will observe a mixture of rain/snow this
afternoon (rain in the eastern Columbia River Gorge) before
changing to all snow overnight. The forecast was updated to
increase temperatures in several locations where temperatures this
morning are already in the mid to upper 30s. However, dewpoints
are in the 20s so the transition to all snow will likely occur
quickly for many areas. By 6 PM this evening, the front will
become stationary just south of the WA/OR border. The Winter
Weather Advisory for snow covering the Blue Mtn Foothills, the
Lower Columbia Basin of Oregon, and north central Oregon is on
track where 2-4 inches of snow are expected through Saturday
morning. One area that could reach 4 or more inches will be the
southern Blue Mtn Foothills in the Condon/Fossil areas with
amounts just shy of warning criteria. The Blue Mountains will
observe about 2-5 inches of snow. Less than one inch is expected
in the Eastern Columbia River Gorge and areas north of the Horse
Heaven Hills and in the Kittitas/Yakima Valleys. 1-3 inches of
snow are forecast for the remainder of the forecast area. Wister
&&
.AVIATION...18Z TAFs...A cold front will move gradually south
across the region through the next 24 hours. This front will bring
decent chances of snow to most TAF sites. Best chances for
persistent snow will be at KALW, KPDT, KDLS, KRDM and KBDN. KDLS
will see rain initially before changing to snow around mid evening.
Meanwhile KPDT, and possibly KALW, will see a mix of rain and snow
this afternoon. KPSC will see some light snow through the afternoon
and early evening, while KYKM will see a few snow showers this
afternoon. Winds will generally be 10 kts or less, though KBDN will
see southwest winds of 10-15 kts at times today. 90
&&
.PREV DISCUSSION... /issued 313 AM PST Fri Dec 22 2017/
LONG TERM...Sunday through Thursday...Models have been very
inconsistent and ensembles have significant differences. This
gives very low confidence in details of timing and strength during
the extended period. The main change was to increase pops Sunday
and Christmas Day. Upper level ridge will move east Sunday as next
system approaches WA and OR. Snow will spread across the area
Sunday morning. Areal coverage should increase throughout the day
as a frontal system moves through eastern WA and OR. An upper
level ridge will amplify off the coast Monday. Weak isentropic
lift may produce light snow at times on Monday. For the rest of
the long term period the ensembles show overlapping ridges and
trough so I did not change existing forecast of varying chances of
light snow. Tuesday, the GFS shows a system moving across the
area but weakening as it gets sheared apart as it moves into the
aforementioned ridge. The ECMWF holds onto the upper ridge another
24 hours before pushing the next disturbance onshore Tuesday
night. Temperatures will remain below normal with cold air in
place. Coonfield
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 35 21 28 17 / 90 90 30 20
ALW 38 21 30 19 / 80 60 10 20
PSC 34 21 31 20 / 60 20 10 20
YKM 33 21 30 17 / 60 20 10 20
HRI 36 23 31 18 / 80 70 20 20
ELN 34 17 27 14 / 60 20 10 20
RDM 39 22 31 17 / 20 60 50 20
LGD 33 19 28 19 / 80 80 30 20
GCD 34 22 31 18 / 40 80 40 20
DLS 44 28 34 23 / 70 90 20 20
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Winter Weather Advisory until 4 AM PST Saturday for ORZ044-507-
508-510.
WA...Winter Weather Advisory until 4 AM PST Saturday for WAZ029.
&&
85/90The national radar mosaic for the moment the first event began.
5 heavy snow. Local standard time, as filed.
Measured 6 inches of snow at Pilot Rock in Umatilla county.
Estimated 6 inches of snow at Island City in Union county.
Measured 5 inches of snow at Condon in Gilliam county.
Estimated 11 inches of snow at Lucky Strike Snotel, 11 miles NNE of Ukiah in Umatilla county. Elevation 4970 feet.
Measured 6 inches of snow at John Day in Grant county.
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, December 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: 729812, 729813, 729811, 730399, 730402.