A mesoscale low with embedded thunderstorms tracked northeast across the Blue Mountain foothills, producing strong wind gusts across portions of Umatilla, OR and Walla Walla, WA counties the afternoon of the 1st.
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The episode as NWS PDT wrote it up.
A mesoscale low with embedded thunderstorms tracked northeast across the Blue Mountain foothills, producing strong wind gusts across portions of Umatilla, OR and Walla Walla, WA counties the afternoon of the 1st.
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 Apr 1, 3:14 PM PST, 1 hour 56 minutes earlier. Its key messages:
Area Forecast Discussion
National Weather Service Pendleton OR
414 PM PDT Wed Apr 1 2026
.KEY MESSAGES...
1. Showers and isolated afternoon thunderstorms today
2. Mountain snowfall, Significant snow Oregon Cascades, moderate
snow Wa Cascades
*Winter Storm Warning and Advisories Issued*
3. Breezy to windy conditions today through Thursday
&&
.DISCUSSION...
Current radar showers showers steadily moving over the eastern
portion of the Basin with showers beginning to develop over the
Cascades. This mornings observation here in Pendleton recorded 0.03
inches of rain so far with other ground observations showing the
last three hours have seen 0.01 inches along the eastern mountains
and 0.06-0.09 through the Tri-Cities. Showers will continue to
linger through the day today with 70-90% of the NBM raw ensembles
showing 24 hour precipitation amounts nearing 0.15-0.25 inches by 11
PM. Along the leading edge of the incoming front, models show just
enough forcing to pop off a thunderstorm or two. HREF ensembles show
that 70% of the members are in agreement that there is 15-25%
probability of the southeast and eastern portion of the CWA will see
thunderstorms this afternoon and evening. The LREF ensembles showed
the region could see CAPE values as high at 250 J/kg with 60% some
confidence and also shear values nearing 25 to 30 kts and steepening
lapse rates. Not only are there the risks of thunderstorms, but
models also show the potential for outflow winds reaching 30-40 mph
with 50% confidence.
Models show a robust upper level low with a front working its way
onshore through the day today and into Thursday. This will continue
to bring the lingering showers mentioned earlier as well as mountain
snow. A Winter Storm Warning is in effect until 5 PM Thursday for
the east slopes of the OR Cascades for total snow accumulations
between 9 to 14 inches with 70-90% confidence. A Winter Weather
advisory is in effect for the east slopes of the WA Cascades through
11 AM Thursday for up to 7 inches of snow with 60-80% confidence.
NBM shows snow levels will drop to near 1500-2000 feet as the front
tracks eastwards allowing for light snow accumulations to occur
through the Ochoco-John Day Highlands and portions of central OR as
well as the Grande Ronde Valley overnight with 30-50% confidence.
Models show a tightening of the surface pressure gradients and in
house pressure gradient calculations have an 11 mb gradient that
will form across the region. Highest winds will occur Thursday with
60-80% confidence of winds reaching 30-35 mph gusts along the wind
prone areas and through the mountain gaps. Elsewhere will see breezy
conditions with 20-25 mph gusts with 60-80% confidence.
Lastly, models are in relatively firm agreement with the next
incoming system Friday. Clusters also show high confidence the the
upper level ridge moving in over the weekend. Dry and warmer
temperatures are expected peaking Sunday. 90
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
VFR conditions prevail this afternoon across the region.
However, as rain redevelops, there could be some local MVFR CIGS
especially if the rain is a bit heavier. For BDN and RDM some
light snow could bring MVFR toward morning as well. Otherwise,
any gusty winds this afternoon and early evening will decrease
over the next few hours. However, gusty winds in the 20 to 25 kt
range will develop in the late morning to early afternoon at
all sites on Thursday.
&&
.Preliminary Point Temps/PoPs...
PDT 34 50 32 59 / 100 60 10 0
ALW 37 50 37 59 / 100 60 20 0
PSC 38 58 35 63 / 90 30 0 0
YKM 31 56 32 61 / 60 20 0 0
HRI 36 55 34 62 / 90 30 0 0
ELN 32 49 32 57 / 80 30 0 0
RDM 26 47 22 61 / 70 40 0 0
LGD 32 45 29 58 / 100 80 40 0
GCD 29 43 26 57 / 90 80 20 0
DLS 36 55 35 64 / 70 30 0 0
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
WA...Winter Weather Advisory until 11 AM PDT Thursday for WAZ522.
OR...Winter Storm Warning until 5 PM PDT Thursday for ORZ509.
&&
DISCUSSION...90
AVIATION...77Special Weather Statement
National Weather Service Pendleton OR
440 PM PDT Wed Apr 1 2026
ORZ044-507-508-WAZ028-020015-
Foothills of the Northern Blue Mountains of Oregon OR-
Foothills of the Southern Blue Mountains of Oregon OR-
Lower Columbia Basin of Oregon OR-
Lower Columbia Basin of Washington WA-
440 PM PDT Wed Apr 1 2026
...STRONG THUNDERSTORMS WILL IMPACT NORTHEASTERN MORROW...
NORTHWESTERN UMATILLA AND SOUTHEASTERN BENTON COUNTIES THROUGH 515 PM
PDT...
At 440 PM PDT, Doppler radar was tracking strong thunderstorms along
a line extending from 10 miles south of Irrigon to 18 miles south of
Echo. Movement was northeast at 40 mph.
HAZARD...Wind gusts of 50 to 55 mph and pea size hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor hail damage to vegetation is
possible.
Locations impacted include...
Hermiston, Pendleton, Umatilla, Stanfield, Echo, Holdman, Rieth,
Plymouth, Cayuse, Mission, and northwestern Umatilla Reservation.
This includes the following highways...
Highway 11 between mile markers 1 and 8.
Highway 395 between mile markers 1 and 24, between mile markers 12
and 14, and between mile markers 1 and 12.
Interstate 82 between mile markers 115 and 131.
Interstate 84 between mile markers 174 and 223.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
These storms may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.
To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
office in Pendleton Oregon.
&&
LAT...LON 4559 11860 4553 11865 4542 11894 4552 11907
4549 11907 4545 11902 4540 11904 4537 11908
4546 11912 4547 11919 4544 11920 4543 11922
4573 11958 4618 11926 4564 11849
TIME...MOT...LOC 2340Z 216DEG 37KT 4574 11945 4547 11916
MAX HAIL SIZE...0.25 IN
MAX WIND GUST...55 MPH
BLSpecial Weather Statement
National Weather Service Pendleton OR
515 PM PDT Wed Apr 1 2026
ORZ044-507-WAZ028-029-020100-
Foothills of the Northern Blue Mountains of Oregon OR-
Lower Columbia Basin of Oregon OR-
Foothills of the Blue Mountains of Washington WA-
Lower Columbia Basin of Washington WA-
515 PM PDT Wed Apr 1 2026
...STRONG THUNDERSTORMS WILL IMPACT NORTHWESTERN UMATILLA...
SOUTHEASTERN BENTON AND SOUTHWESTERN WALLA WALLA COUNTIES THROUGH 600
PM PDT...
At 515 PM PDT, Doppler radar was tracking strong thunderstorms along
a line extending from near Mission to 8 miles west of Helix to near
Holdman to 10 miles east of Hermiston. Movement was northeast at 35
mph.
HAZARD...Wind gusts of 50 to 55 mph and pea size hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor hail damage to vegetation is
possible.
Locations impacted include...
Walla Walla, Hermiston, Pendleton, Milton-Freewater, Athena, Weston,
Adams, Helix, Umapine, Wallula, Holdman, Touchet, Mission,
northwestern Umatilla Reservation, and Lowden.
This includes the following highways...
Highway 11 between mile markers 1 and 34.
Highway 12 between mile markers 300 and 328.
Highway 395 mile marker 1 and near mile marker 6.
Interstate 84 between mile markers 210 and 217.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
These storms may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.
To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
office in Pendleton Oregon.
&&
LAT...LON 4591 11830 4613 11854 4619 11868 4620 11892
4583 11929 4582 11904 4577 11892 4558 11871
TIME...MOT...LOC 0015Z 214DEG 29KT 4572 11868 4586 11883 4590 11895
4590 11908
MAX HAIL SIZE...0.25 IN
MAX WIND GUST...55 MPH
BLSpecial Weather Statement
National Weather Service Pendleton OR
553 PM PDT Wed Apr 1 2026
ORZ502-507-WAZ028>030-020130-
Foothills of the Northern Blue Mountains of Oregon OR-
Northern Blue Mountains of Oregon OR-Northwest Blue Mountains WA-
Foothills of the Blue Mountains of Washington WA-
Lower Columbia Basin of Washington WA-
553 PM PDT Wed Apr 1 2026
...STRONG THUNDERSTORMS WILL IMPACT NORTHEASTERN UMATILLA...WALLA
WALLA...SOUTH CENTRAL FRANKLIN AND SOUTHWESTERN COLUMBIA COUNTIES
THROUGH 630 PM PDT...
At 553 PM PDT, Doppler radar was tracking strong thunderstorms along
a line extending from near Wallula to 7 miles northeast of Touchet to
near Walla Walla to 7 miles east of Weston. Movement was northeast at
40 mph.
HAZARD...Wind gusts of 50 to 55 mph and pea size hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor hail damage to vegetation is
possible.
Locations impacted include...
Walla Walla, College Place, Waitsburg, Prescott, Dixie, Huntsville,
Garrett, Snake River, Eureka, and Kooskooskie.
This includes the following highways...
Highway 11 between mile markers 33 and 35.
Highway 12 between mile markers 326 and 365.
Highway 204 near mile marker 9.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
These storms may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.
To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
office in Pendleton Oregon.
&&
LAT...LON 4647 11875 4644 11826 4633 11802 4614 11792
4578 11828 4595 11838 4608 11860 4612 11892
TIME...MOT...LOC 0053Z 215DEG 34KT 4614 11887 4612 11857 4599 11835
4585 11827
MAX HAIL SIZE...0.25 IN
MAX WIND GUST...55 MPH
BLThe Pendleton radar (KPDT), 75 km away, was scanning. The volume nearest the first event began at 01:12 UTC.
1 thunderstorm wind. Local standard time, as filed.
The Walla Walla county emergency manager reported a healthy tree had blown down from strong winds that moved through the area around 1820 PDT on the 1st.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Washington in 2026Every state in 2026This day in weather historyWarnings in Washington, April 2026
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: 1335088.