977
NOUS45 KBOI 280107 CCA
PNSBOI
IDZ012-ORZ064-281245-

Public Information Statement...Corrected
National Weather Service Boise ID
633 PM MDT Thu Jun 27 2024

...NWS Damage Survey for 6/26/24 Nyssa and Western Parma Severe Thunderstorm...

On June 26th at approximately 1:00 PM MDT, a cluster of storms
developed west of the Idaho-Oregon border near Nyssa, Oregon in
Malheur County. The strongest cell intensified rapidly as it
approached the border, and at 1:32 PM MDT a Severe Thunderstorm
Warning was issued for parts of Malheur, Canyon, and Payette
counties for 60 mph wind gusts and 1" diameter hail. At the time
of the warning, the storm was still intensifying. As the storm
approached the border and Nyssa, it developed a strong
reflectivity core and maintained that core as it moved through
Nyssa at around 1:54 pm. At 1:57 PM MDT, a microburst signature
began to appear on radar with divergent winds near the surface.

During the 6/27 survey, the damage was found to be consistent
with a wet microburst. The direction of downed trees, toppled
crops, and strewn debris was indicative of straightline winds from
the west and northwest caused by an outflow from the microburst.
The most extensive damage occured in areas south and east of the
storm, where the wind was coming out of the north and west. The
storm also caused minor flooding of roads and accumulated water of
at least 6 ft deep in the East Main Street railroad underpass.

This survey was focused on the area surrounding Nyssa, Oregon in
parts of Eastern Malheur County, Northwestern Canyon County, and
Southwestern Payette County. The storm continued northeast
impacting areas beyond the survey.

.Wind Damage...

Estimated Peak Wind:70-80 mph
Injuries:1
Fatalities: 0

Wind Summary: Maximum snapped tree diameters were estimated to be
in excess of 1 foot. Trees with larger trunk diameters were
toppled at the roots. Trees fell onto buildings and a car.
Barns/sheds exhibited stripped roofing, with metal roof sheets
being blown several hundred feet from their source. One large
warehouse had a wall ripped open, and surrounding piles of pallets
were scattered. Fields of crops were blown over, and a couple
onion fields had exposed heads. A small shed and camper were
overturned. Ten power poles were shattered at their bases, but at
the time of the survey they had been replaced. A house was
reported to have a window shattered, and the rapid increase in
pressure inside the house caused a crawlspace door to shoot
upwards and for trusses to be broken. One barn had its doors
ripped off by the wind. The injury was a broken arm caused by
blowing debris, believed to be a tree limb.


.Hail Damage...

Estimated Peak Diameter:1 inch
Injuries:               0
Fatalities:            0

Hail Summary: While most damage was caused by the wind, several
small branches were stripped from trees in the town of Nyssa where
most hail is expected to have fallen. At least one field of corn
was shredded by hailstones whereas most were just blown over.


.Flooding...

Injuries:               0
Fatalities:            0

Flooding Summary: Evidence of minor flooding was visible on many
roads in and around Nyssa and portions of Canyon County northwest
of Parma. Mud and gravel were covering a few roads. The railroad
underpass along E Main Street in Nyssa had a waterline that was at
least 6 ft above the lowest point of the underpass.

&&

NOTE:
The information in this statement is still preliminary and
subject to change pending final review of the events and
publication in NWS Storm Data.

$$