A deep Pacific low pressure system that passed to the northwest of the forecast area on Oct. 24th created a tight and strong surface pressure gradient across the eastern mountains of OR and far southeast WA as well as a strong 850mb jet across the region.
Every event with a place to put it; 2 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 deep Pacific low pressure system that passed to the northwest of the forecast area on Oct. 24th created a tight and strong surface pressure gradient across the eastern mountains of OR and far southeast WA as well as a strong 850mb jet across the region. This in turn led to strong winds mixing down into north facing foothill locations in eastern OR and WA.
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 Oct 24, 3:59 AM PST, 1 minute earlier.
Area Forecast Discussion
National Weather Service Pendleton OR
459 AM PDT Sun Oct 24 2021
updated the aviation discussion
.SHORT TERM...Today through Tuesday night...Powerful upper and
surface low off the WA coast will initially deepen today as it moves
eastward and then gradually fill as it moves onshore into SW BC
Monday evening. As this occurs a secondary trough will move into
California. The most impactful weather in the short term will occur
today. A 986 mb surface low will move across the Columbia Basin
which will act to enhance the sely pressure gradient across the Blue
Mountains. The HREF, HRRR, and experimental NBM 4.1 are all
indicating damaging wind gusts for the Blue Mountain Foothills and
nearby Blue Mountains as well as the Grande Ronde/Wallowa Valleys.
The NBM 4.1 has been consistent in showing winds of 70-80 mph right
along the base of the Blue Mountains and impacting communities along
Highway 11 in Umatilla County and near and east of Walla Walla in
Walla Walla County. Although the HREF and HRRR are not quite as
bullish they are indicating potential for 60-70 mph winds. The
Grande Ronde Valley and Wallowa County look to have more like 50
to 60 mph gusts but Joseph could see higher gusts due to
downsloping off the Wallowas. The Extreme Forecast Index (EFI) is
nearly maxed out for wind gust over the Northern Foothills and
Northern Blues in Oregon which provides an additional degree of
confidence in the forecast. With all this in mind will keep the
wind highlights in place for today. Areas of rain will spread
northeast across the forecast area today with .25 to locally.75
inch amounts possible in central Oregon and the Cascade east
slopes. Winds will decrease this evening and showers will move to
the eastern portion of the forecast area. Monday through Tuesday
the 500 mb heights will begin to rise and the region will be in NW
flow aloft. Most of the rain showers will be over the mountains.
There is some potential for stronger west winds Tuesday afternoon
and Tuesday night with a cold frontal passage. 78
.LONG TERM...Wednesday through Saturday. An intense low pressure
system over the ne pacific is forecast to spin a disturbance and
its associated warm front into WA/OR Wednesday with increasing
clouds and pcpn. Breezy southerly winds are also expected. Much of
the pcpn drifts north on Thursday followed by another round of
pcpn expected Friday. A cold front is also forecast to move
through the region and behind the front breezy to west winds are
possible across our region. Drier conditions are expected for next
weekend as a ridge of high pressure builds into the two state
area. Temperatures should be above normal until the cold front
passes through the region on Friday. The EOF/Var increases Friday
raising the uncertainty so will trend temps somewhat lower than
guidance. Otherwise the models come more into agreement with the
ridge of high pressure and drier conditions are expected next
weekend.
&&
.AVIATION...Windy conditions expected today across all taf sites
with wind gusts between 30 to 40 kts until 02z. Then between 25 to
35 kts thereafter. However taf sites kalw and kpdt may experience
wind gusts between 40 to 50 kts from 14z to 20z. In addition areas
of mvfr conditions can be expected as a storm system brings rain to
the area. Lcl ifr conditions may be approached in heavier showers.
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 62 42 60 40 / 70 70 20 20
ALW 63 46 63 44 / 70 70 20 30
PSC 65 43 64 44 / 80 80 10 20
YKM 57 37 57 37 / 90 50 30 40
HRI 66 42 63 44 / 80 80 10 20
ELN 54 36 54 37 / 90 60 30 40
RDM 60 33 55 36 / 90 50 20 40
LGD 55 41 56 37 / 80 70 30 30
GCD 58 42 57 37 / 90 70 20 10
DLS 62 42 60 46 / 90 40 50 60
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Wind Advisory until 5 PM PDT this afternoon for ORZ505-506-511.
High Wind Warning until 5 PM PDT this afternoon for ORZ049-050-
502-503-507-508.
WA...High Wind Warning until 5 PM PDT this afternoon for WAZ029-030.
&&
SHORT TERM...78
LONG TERM....97
AVIATION...97The national radar mosaic for the moment the first event began.
2 high wind. Local standard time, as filed.
The ASOS station KYKM measured a wind gust of 58mph at 1822 PDT.
The ASOS station KALW measured a 59 mph gust at 1603 PDT. The co-op observer K7KLA 4 miles ESE of Walla Walla measured a wind gust of 59 mpg at 0713 PDT. A report from the Walla Walla Union Bulletin newspaper indicated that a tree had blown over in a local cemetery and that strong winds led to 700 customers losing power in Walla Walla.
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, October 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: 991011, 991013.