Southwest Riverton Struck By 74 mph Wind Gust on July 27

Damaging thunderstorm winds occurred in southwest Riverton late Monday afternoon.  The area most impacted centered around the Riverton Country Club where numerous trees were damaged by a recorded 74 mph wind gust.  The tree damage (see images below) was primarily centered around holes #1, #8, #9, #10, #11, and #17, covering the northwest section of the golf course.  The 74 mph recorded gust was nearly in the middle of the area of greatest damage.  Nearby wind gusts, approximately one mile west and one mile east of the damage area, were measured at 45 and 46 mph, respectively.  It appears that the enhanced damage area may have been caused as a a result of the storm beginning to collapse over this area.

The storm responsible for the damage began near Crowheart after 4:30 PM MDT.  The storm gathered strength as it encountered an earlier outflow boundary that was draped west-to-east across the Wind River Valley (see images below).  Shortly after 5:00 PM the storm took on characteristics indicative of a severe thunderstorm and a warning was issued at 5:08 PM.  The storm closely followed U.S. Highway 26 toward Riverton and produced more than one inch of rain near Kinnear along with very small hail.  One rancher claimed it was the hardest he had seen it rain in his 35 years at his location near Kinnear.  The storm eventually took aim on southwest Riverton after 5:30 PM.  Radar imagery, as seen below, showed winds of 60 to 64 mph between 5:44 and 5:52 PM just south of U.S. Highway 26.

Radar Imagery
Click Thumbnail Image for Larger View
(All images courtesy of NWS/NOAA)

4:44 PM MDT 0.5 degree Reflectivity 5:01 PM MDT 0.5 degree Reflectivity 5:10 PM MDT Composite Reflectivity 5:39 PM MDT 0.5 degree Reflectivity
WFO Riverton radar image
of 4:44 PM MDT 0.5 degree
Reflectivity. Note outflow
boundary moving south
across the northern Wind
River Basin.
WFO Riverton radar image
of 5:01 PM MDT 0.5 degree
Reflectivity.  By this time,
the outflow boundary has
interacted with the storm to
provide additional lift.
WFO Riverton radar image
of 5:10 PM MDT Composite
Reflectivity.  The storm had
blossomed in the past 10
minutes necessitating a
Severe Thunderstorm
warning.

WFO Riverton radar image
of 5:39 PM MDT 0.5 degree
Reflectivity.  At this time, the
leading edge of the outflow
wind is just reaching the NWS
office northwest of Riverton.

       
 5:39 PM MDT Composite Reflectivity  5:44 PM MDT 0.5 degree Velocity  5:52 PM MDT 0.5 degree Velocity  5:52 PM MDT Composite Reflectivity

WFO Riverton radar image
of 5:39 PM MDT Composite
Reflectivity.  Core of the
severe thunderstorm is
notably south of U.S.

Highway 26.

WFO Riverton radar image
of 5:44 PM MDT 0.5 degree
Reflectivity.  The area circled
in white denotes inbound
(toward the radar - northwest)
speeds of 60 mph.

WFO Riverton radar image
of 5:52 PM MDT 0.5 degree
Reflectivity.  The area circled
in white denotes outbound
(away from the radar -
northwest) speeds of 64 mph.
WFO Riverton radar image
of 5:52 PM MDT Composite
Reflectivity.  The core of the
storm is clearly impacting areas
southwest of downtown Riverton
at this time.

 

Damage Pictures
Click Thumbnail Image for Larger View
(All photos courtesy of NWS/NOAA)

Tree limbs up to 9 Inches in Diameter Laying on a Golf Cart Path A 40-foot spruce tree toppled near the #1 tee at the Riverton Country Club. Tree damage near the #11 tee at the Riverton Country Club. Tree damage between #11 and #17 fairways at the Riverton Country Club.
Tree limbs, some up to 9"
inches in diameter were
tossed to the ground near
Village Drive.
A 40-foot spruce tree was
toppled near the #1 tee
at the Riverton Country Club.
Tree damage, like this near
#11 tee, was strewn about
several holes on the
northwest section of the
Riverton Country Club.
Evidence of more tree
damage between the #11
and #17 fairways at the
Riverton Country Club.



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