An Atmospheric River brought a round of heavy mountain snow to the forecast area from the early morning hours of Sunday the 29th into early Monday morning the 30th.
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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 PDT wrote it up.
An Atmospheric River brought a round of heavy mountain snow to the forecast area from the early morning hours of Sunday the 29th into early Monday morning the 30th.
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 28, 9:45 PM PST, 3 hours 15 minutes earlier.
Area Forecast Discussion
National Weather Service Pendleton OR
945 PM PST Sat Dec 28 2024
Updated Aviation Discussion
.SHORT TERM UPDATE...A moist warm front has spread precipitation
across western OR and is now bringing snow and rain to the east
slopes of the OR Cascades as well as the Bend/Redmond areas. Based
on the latest observations and webcams, snow levels are around
4000 feet. Snow levels are a little lower than in the forecast
that shows 4500 feet. Even a small difference in the snow levels
have made for big differences in the forecast. Several of the
populated areas and areas along HWY97 are around 4000 feet,
including La Pine and Lava Butte. Reports of 3 inches of new snow
have been reported in La Pine. Snow levels will increase overnight
to around 5500-6000 feet over Deschutes County with snow changing
over to rain.
Winter Storm Warnings have been posted for our east slopes of the
WA/OR Cascades and the northern Blue Mountains, starting 1 AM
Sunday and continuing through Monday morning. The front does have
a weak Atmospheric River associated with it...approximately
250-400 kg/m/s IVT...as well as upper level ascent from a 150+ kt
upper level jet to bring moderate to heavy precipitation. The
rise in snow levels will be brief due to the cold air advection
aloft associated with the shortwave trough and surface cold front
pushing east of the Cascades Sunday afternoon. Surface high
pressure building behind the front will result in breezy to windy
conditions, but the chance for wind advisory gusts of 45-55 mph is
only about 20-40% with the best chance over north central OR and
the southern Blue Mtn Foothills.
River rises have been observed throughout the forecast area, but
all show levels within their banks. There will be a temporary
break in precipitation on Tuesday then the arrival of another
Pacific frontal system on New Years Day. These back-to-back
systems will keep levels on the rise but no flooding expected at
this time. Wister/85
&&
.AVIATION...06Z TAFs...Snow has been observed at BDN and likely
creating snow-covered runways. However, snow levels increasing to
around 5500 feet tonight will result in snow changing to rain. Rain
recently was reported in RDM. Rain will spread to the other terminal
airports over the next 3-6 hours. CIGS and VSBY will lower to IFR to
LIFR and will continue through Sunday afternoon with steady light to
moderate precipitation. The passage of a cold front will cause winds
to increase Sunday afternoon and evening...WSW 10-20 kt gusting to
20-30 kt. Conditions will improve to MVFR or VFR with scattered
showers in the afternoon. Wister/85
&&
.PREV DISCUSSION... /issued 341 PM PST Sat Dec 28 2024/
SHORT TERM...Today through Monday night...
Key Messages:
1. Significant mountain snow tonight through Monday morning.
*Winter Storm Warnings and Advisories issued*
2. Breezy winds this afternoon, returning Sunday into Monday.
Current radar and visible satellite imagery showing light to
moderate returns along the west slopes of the Cascades, with some
isolated returns beginning to spill into the Basin and along the
east slopes under partly to mostly cloudy skies. These conditions
are a result of a transient upper level ridge breaking down and
shifting east as an upper level trough approaches the coast. This
trough will be passing just to our south, bringing with it a weak
Atmospheric River with ample moisture in the form of mountain snow
and lower elevation rainfall. The attendant frontal warm front will
approach from the south Sunday morning before the cold front moves
in from the west. This warm front will be responsible for increasing
snow levels from 4000-4500 feet this afternoon/evening to 3000-6000
feet north-to-south during the early morning hours on Sunday before
dropping back down to 2500-4500 feet by Sunday afternoon. As a
result, substantial mountain snowfall is anticipated for elevations
of 3500 feet and above across the Cascades and 4000 feet and above
across the northern Blue Mountains. Due to the track of the incoming
system, the Oregon Cascades are expected to receive the highest snow
amounts, with 10-18 inches likely. The east slopes of the Washington
Cascades are expected to receive 7-15 inches and the northern
Blue Mountains accumulating 8-16 inches of snow. Confidence in
these snow amounts is moderate to high (70-90%) as the NBM
suggests a 50-70% of 12 inches of snow or more over the upper east
slopes of the Washington Cascades, a 55-75% chance of 10 inches
or more snow across the northern Blue Mountains, and a 70-85%
chance of 8 inches or more snowfall over the east slopes of the
Oregon Cascades. Thus, Winter Weather Warnings have been issued
over the aforementioned areas until 4 AM Monday for the Oregon and
Washington Cascade zones above 3500 feet and until 10 AM Monday
for the northern Blue Mountains above 4000 feet.
Breezy winds have already been experienced across the Simcoe
Highlands, north-central Oregon, and the southern Blue Mountain
foothills as observations and guidance aligned to allow gusts of 50
mph out of the southwest to occur. This warranted the issuance of a
Wind Advisory over these zones, which will be allowed to expire at 4
PM due to winds beginning to subside. The warm front, associated
with the upper level system, will arrive from our south early Sunday
morning before the cold front swings through during the afternoon.
These two fronts will allow winds to heighten across the Simcoe
Highlands and the Blue Mountain foothills as sustained winds of 20-
30 mph out of the southwest and gusts up to 40 mph. Confidence in
these wind amounts is moderate to high (50-70%) as the NBM
highlights a 65-85% chance of gusts reaching 40 mph or greater over
the aforementioned areas. When bumping up probabilities to 45 mph,
the NBM suggests there to be a 55-75% of reaching advisory-level
wind gusts (45 mph or greater).
Widespread rainfall is expected late tonight through Sunday
afternoon as conditions slowly dry out through the remainder of the
Monday. Rain amounts of 0.40-0.70" are expected over Central Oregon
and the John Day-Ochoco Basin, 0.20-0.45" across the Blue Mountain
foothills, lower elevations of the Columbia Basin, and the
Yakima/Kittitas Valleys. Confidence in these rain amounts is
moderate to high (60-80%) as the NBM suggests a 75-95% chance of
0.40" across Central Oregon and the John Day-Ochoco Basin and a 45-
95% chance of 0.20" or more over lower elevations of the Columbia
Basin, northern Blue Mountains, and the Yakima/Kittitas Valleys. 75
LONG TERM...Tuesday through Saturday...Models and ensembles are
in good agreement with the overall pattern of an initial upper level
shortwave late Tuesday into Wednesday before a much stronger system
approaches the coast early Friday. Differences do arise in regards
to how quickly the ridge weakens and moves east with Wednesday's and
Friday's system. These two systems will again bring widespread rain
and mountain snowfall across the region beginning early Wednesday
morning and extending through much of the workweek. Snow levels will
be slowly increasing through the week, from 3000-5000 feet with
Wednesday's system and 4500-6500 feet with Friday's system. 56% of
ensemble clusters suggests a weaker upper level ridge which would
lead to increased rain chances and a 5-10% increase in chances of
0.10" of rainfall, which is a 20-40% chance across lower elevations
of the Columbia Basin Central Oregon, and the Blue Mountain
foothills. The next chance of widespread rain will come on Friday as
0.01-0.10" will be possible across lower elevations of the Basin,
and 0.10-0.20" of rain expected along the foothills of the northern
Blue Mountains. 75
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 39 45 34 44 / 70 90 30 10
ALW 40 45 36 45 / 50 90 60 20
PSC 40 45 37 48 / 50 90 20 0
YKM 34 42 29 44 / 50 80 20 0
HRI 41 46 36 47 / 80 100 20 0
ELN 31 38 28 42 / 20 90 30 10
RDM 36 44 27 40 / 90 80 20 0
LGD 36 45 31 40 / 80 90 50 30
GCD 34 45 25 38 / 90 80 30 10
DLS 39 46 36 46 / 90 90 50 20
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Winter Storm Warning from 1 AM Sunday to 10 AM PST Monday for
ORZ502.
Winter Storm Warning from 1 AM Sunday to 4 AM PST Monday for
ORZ509.
WA...Winter Storm Warning from 1 AM Sunday to 10 AM PST Monday for
WAZ030.
Winter Storm Warning from 1 AM Sunday to 4 AM PST Monday for
WAZ522.
&&
SHORT TERM...75/85
LONG TERM....75
AVIATION...85The national radar mosaic for the moment the first event began.
1 heavy snow. Local standard time, as filed.
Social media post reported 12 inches of new snow 3 miles west of Sunriver. ODOT also reported 15 inches of storm total snow at Santiam Pass.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Oregon in 2024Every state in 2024This day in weather historyWarnings in Oregon, December 2024
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: 1226378.