An upper-level shortwave trough and strong cold-frontal boundary pushed through the region the morning of Feb 13th followed by a period post-frontal showers the rest of the 13th driven by anomalous cold air aloft. A secondary wave feature dropping southward from BC the night of the 13th into the 14th provided a period of substantially increased snow showers over the mountains, particularly the…
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The episode as NWS PDT wrote it up.
An upper-level shortwave trough and strong cold-frontal boundary pushed through the region the morning of Feb 13th followed by a period post-frontal showers the rest of the 13th driven by anomalous cold air aloft. A secondary wave feature dropping southward from BC the night of the 13th into the 14th provided a period of substantially increased snow showers over the mountains, particularly the Oregon Cascades.
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 Feb 13, 2:34 AM PST, 26 minutes earlier.
Area Forecast Discussion
National Weather Service Pendleton OR
234 AM PST Mon Feb 13 2023
.SHORT TERM...Today through Wednesday night...Winter Weather
advisory is in affect through tonight above 3000 feet for the east
slopes of the Wa Cascades. A Winter Weather warning above 4500 feet
for the Or Cascades and a Winter Weather Warning is in affect
through tomorrow morning for the Northern Blue Mountains. Wind
advisory is in affect for Eastern Gorge of Or and Wa, lower Basin of
Or, foothills of the Blues and north central Or from now until
tomorrow morning. Current radar is showing a the leading edge of the
shortwave is onshore already bringing some precipitation to the
Cascades. Nighttime satellite imagery is showing mid to low level
clouds over the eastern portion of the region. Ground observations
is also showing that the winds are beginning to pick up already,
especially through the Dalles.
Models are in firm agreement with the placement and timing of the
cold front. The cut off low has moved even deeper to the south and
the ridge has flattened out bringing in WNW flow aloft. Temperatures
will remain above seasonal average through today but will decrease
with the passage of the cold front and shift in flow aloft.
Temperatures today will be in the mid 40s to low 50s across much of
the region with 30s in the mountains. As the day progresses, models
stay in firm agreement with the upper level low moving into the
region and an increase in precipitation. Pressure gradients will
tighten even more bringing with it gusty conditions. NBM wind
probabilities of 47 mph gusts are above 70% so confidence that the
winds will meet advisory criteria is moderate to high. Confidence in
the snow totals is high in that the ensembles and guidance show the
probabilities of 90% and above. Snow totals for the east slopes of
the Cascades will see 6 to 10 inches of snow with higher amounts
along the crests, east slopes of the Or Cascades will see 10 to 20
inches and the Northern Blue Mountains will see 8 to 14 inches.
Gusty winds will cause blowing snow along the Cascades and Blue
Mountains so be prepared for difficult driving conditions along the
I-84, I-90 and highway 12. Snow levels will decrease behind the
front bringing the levels to just about ground level so if there is
any remaining precipitation, the lower elevations could see a brief
dusting of less than an inch. Confidence in low level snow is
20-30%.
By Tuesday guidance is in agreement that the original system will be
replaced by another upper level low moving down the coast and
clipping the Or Cascades as it moves inland. This will continue the
snowfall over the Or Cascades through Tuesday late morning. By
Tuesday evening the system will have already exited the region and
dry conditions will return through the remainder of the period ahead
of more mountain snow. Northerly flow aloft will keep the
temperatures cool through Wednesday with temperatures both Tuesday
and Wednesday being in the low to mid 40s with high 20s to low 30s
in the elevations. Primary concerns with the temperatures will be
overnight when the temperatures will be well below freezing with a
few locations seeing single digits. Bennese/90
.LONG TERM...Thursday through Monday...Models have been in better
alignment with the synoptic pattern in the past several runs. The
weather will be relatively benign through Saturday but winds on
Sunday are looking strong at this time.
The forecast area will be located on the backside of an upper level
ridge on Thursday, and the flow will increase from the southwest.
Meanwhile, an upper level low will deepen off the coast and travel
south. On Thursday night, the low will be off the northern CA coast
while a westerly flow increases over the northern half of WA. There
is a small chance (20 pct) of light snow over the mountains, but
most precipitation will be along the periphery of the closed low
well to the south. The flow will increase from the WNW on Friday,
and there are hints of weak disturbances embedded in the flow that
will enhance orographic precipitation over the mountains, but the
probability of snow remains around 20-40 pct. Eastern WA/OR will
remain under a northwest flow aloft over the weekend. Sunday could
be a windy day. The polar jet will lower south along the mid-
latitudes and a jet streak is progged to sit over WA state. Winds
aloft and at the surface will increase. It's hard to say just how
strong winds will be so far out, but the NBM 50th percentile is
advertising a large area over eastern WA and northeast OR with 30-40
kt wind gusts and 50-55 kts along the exposed ridges. There are
signs that the polar jet will dip a little more to the south on
Monday, creating a back door cold front. Confidence in this
scenario is not very high, as the box whisker plots of the NBM have
large spreads in the maximum temperatures during the mid-week and
there are model differences on the strength of the front. Wister/85
&&
.AVIATION...06z TAFs...Conditions are expected to primarily
remain VFR through the period, however an oncoming system may allow
for brief periods of light precip to fall at times during the day
Monday. Precip type would at first be rain, then snow after sunset.
Amounts are expected to be very light, but a stray shower could make
for localized MVFR conditions at times. Otherwise the main impact
from this system will be wind gusts, which are expected to pick up
around daybreak Monday, reaching 25-35 kts for most sites by the
afternoon. Gusty conditions could prevail into the overnight hours
tomorrow. Cigs will decrease through the day, becoming bkn-ovc less
than 10 kft for most sites by Monday evening. Evans/74
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 45 27 41 23 / 50 40 20 0
ALW 48 28 43 24 / 60 70 20 0
PSC 51 30 47 25 / 20 20 10 0
YKM 48 24 46 20 / 10 10 0 0
HRI 49 29 46 25 / 40 20 10 0
ELN 44 25 42 21 / 10 20 0 0
RDM 41 23 36 13 / 40 50 50 0
LGD 40 24 34 18 / 70 70 30 0
GCD 39 20 34 16 / 70 50 40 0
DLS 48 32 46 26 / 40 30 20 0
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Wind Advisory from 1 PM this afternoon to 1 AM PST Tuesday for
ORZ041-044-507-508-510.
Winter Storm Warning until 4 AM PST Tuesday for ORZ502.
Winter Storm Warning until 10 AM PST Tuesday for ORZ509.
WA...Wind Advisory from 1 PM this afternoon to 1 AM PST Tuesday for
WAZ024.
Winter Storm Warning until 4 AM PST Tuesday for WAZ030.
Winter Weather Advisory until 11 PM PST this evening for WAZ520.
&&
SHORT TERM...90
LONG TERM....85
AVIATION...74The national radar mosaic for the moment the first event began.
2 heavy snow. Local standard time, as filed.
The SNOTEL site HOPO3(Hogg Pass) measured 15 inches of snowfall over a 25 hour period ending at 0900 on Feb 14th.
The SNOTEL site MLKO3(Milk Shakes) recorded 18 inches over a 17 hour period ending at 0300 on Feb 14th, and the SNOTEL site HIRO3(High Ridge) recorded 12 inches in a 15 hour period ending 0300 Feb 14th.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Oregon in 2023Every state in 2023This day in weather historyWarnings in Oregon, February 2023
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: 1083569, 1083566.