A shortwave trough coupled with surface cold front swept across the forecast area on Feb. 25th, producing an initial surge in snowfall across the region with breezy to gusty winds developing behind the frontal passage.
Every event with a place to put it; 1 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.
A shortwave trough coupled with surface cold front swept across the forecast area on Feb. 25th, producing an initial surge in snowfall across the region with breezy to gusty winds developing behind the frontal passage. Behind this system, persistent northwest flow aloft reinforced by a series of shortwaves produced additional snowfall across the forecast area through the early afternoon of Feb. 27th.
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 24, 9:06 PM PST, 3 hours 54 minutes earlier.
Area Forecast Discussion
National Weather Service Pendleton OR
906 PM PST Wed Feb 24 2021
.UPDATE...Minor edits this morning as forecast remains on track.
Upgraded Winter Storm Watch to Warnings for North/South Blues,
Grande Ronde Valley and Wallowa Country from 15Z Thu to 18Z Sat.
Snow begins in WA Cascades overnight, spreading into OR Cascades
and eastern mountains early Thu morning as front slides southeast.
Could be a few rain/snow showers in the Basin, but biggest
impacts will be strong winds behind the frontal passage. Another
front/trough will slide further south into CWA and brings
continued snow the mountains with a better chance for John Day
Basin and the Ochoco-John Day Highlands, where snow amounts
approach warning criteria. Even if snow amounts are lower than
criteria, strong winds could lead to reduced vis in blowing snow.
&&
.AVIATION...06Z TAFs...Increasing mid and high level clouds
tonight becoming bkn-ovc 8-12kft. Chance of rain or snow showers
at or near the taf sites Thu morning with frontal passage.
Ceilings lowering to bkn-ovc 040-060. Could be brief MVFR CIGs.
Mountain snow will continue behind the frontal passage tomorrow
afternoon while taf sites dry out. Winds 5-15kt tonight
increasing to 20-30g30-40kt during by Thu afternoon.
&&
.PREV DISCUSSION... /issued 333 PM PST Wed Feb 24 2021/
SHORT TERM...Tonight through Saturday...A ridge of high pressure
over the region today will move off to the east overnight. This in
turn will allow a shortwave trough in the Gulf of Alaska to move
into southern British Columbia late tonight and Thursday pushing a
cold front across the Pacific Northwest. There will be some
increasing southerly winds mainly over Oregon tonight and then
switch to westerly following the frontal passage across the entire
forecast area. The winds on Thursday will be approaching advisory
levels and then expected to be a little stronger on Friday. Have
decided to issue a wind advisory from midday Thursday through
Friday evening for the Columbia Basin down to central Oregon.
There will be an initial shot of precipitation associated with the
frontal passage and then a cool and moist northwest flow will
develop behind the front with a couple of shortwaves passing through
this flow. This pattern will favor the Cascade crest region and the
eastern Oregon mountains with some significant snow accumulations
Thursday through Saturday. Winter Storm Warnings have been issued
for the Cascade crest and Winter Storm Watches are in effect for the
eastern Oregon mountains. Rest of the forecast area will mainly be
rain shadowed by the Cascade mountains resulting in very little to
just light precipitation.
Conditions will begin to improve Saturday as a ridge of high
pressure over the eastern Pacific begins to nudge inland.
Precipitation will taper off through the day over the mountains and
come to an end by Saturday night. Winds will also be significantly
less.
LONG TERM...Saturday through Wednesday. Storm exiting the region
on Saturday with cold northwesterly upslope flow into the Cascades
and Blues. Lingering snow showers through the day. Otherwise partly
to mostly cloudy skies and breezy. Upper ridge builds in Sunday with
partly cloudy skies and lighter winds. Models in good agreement
through the weekend then diverge significantly on Monday. Will lean
toward a blend of the Euro and Canadian with an upper trough moving
across the Pacific northwest. This will bring a chance of rain with
mountain snow likely and increased winds. Weak upper ridge and
westerly flow Tuesday and Wednesday. Partly cloudy with near normal
temperatures. 94
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 29 47 37 44 / 0 30 20 50
ALW 31 48 38 46 / 0 40 30 60
PSC 33 53 38 51 / 10 30 10 10
YKM 31 51 36 50 / 10 30 20 20
HRI 33 52 39 51 / 0 20 10 30
ELN 29 43 32 43 / 20 40 30 30
RDM 27 47 29 44 / 0 10 20 40
LGD 20 37 31 36 / 0 70 70 80
GCD 23 42 30 38 / 0 30 40 70
DLS 34 48 39 48 / 10 40 40 50
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Winter Storm Warning from 4 AM Thursday to 4 AM PST Saturday for
ORZ509.
Wind Advisory from 10 AM Thursday to 9 PM PST Friday for ORZ041-
044-505-507-508-510-511.
Winter Storm Warning from 7 AM Thursday to 10 AM PST Saturday
for ORZ049-050-502-503.
Wind Advisory from midnight tonight to 1 PM PST Thursday for
ORZ049.
WA...Wind Advisory from 10 AM Thursday to 9 PM PST Friday for WAZ024-
026>029-521.
Winter Storm Warning from 7 AM Thursday to 10 AM PST Saturday
for WAZ030.
Winter Storm Warning from 1 AM Thursday to 10 PM PST Friday for
WAZ520.
&&
UPDATE.......84
SHORT TERM...91
LONG TERM....94
AVIATION.....84The national radar mosaic for the moment the first event began.
2 heavy snow. Local standard time, as filed.
The Fish Lake Snotel 20 miles N of Roslyn, WA measured 20 inches of snowfall at 740pm PST on Feb. 26th. The Potato Hill Snotel 38 miles W of White Swan, WA measured 14 inches of snowfall at 743pm PST on Feb. 26th.
The Ski Bluewood alpine ski area in WA measured 15 inches of snowfall in a 24 hour period ending at 5am PST on Feb. 27th.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Washington in 2021Every state in 2021This day in weather historyWarnings in Washington, February 2021
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: 938516, 938515.