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NOUS45 KCYS 122300

Public Information Statement
National Weather Service Cheyenne, WY
500 PM MDT Fri Jun 12 2020


A Quasi-Linear Convective System (QLCS) with an embedded supercell structure
developed across far SE Carbon County around 2:45pm on 6/6/2020, and moved
across western and northern portions of the Snowy Mountain Range. The overall
radar presentation of the co-located cyclonic rotation at the leading edge of
the reflectivity surge improved near 2:50-2:56pm per the radar scans from KCYS.
The first note of tree damage from the tornado occurred on Forest Service Road 115 
(FS115) that ran west of the main Forest Service Road 100 (FS100) at an elevation 
around 9200 feet. Sporadic softwood pine trees were uprooted along FS115 and fell to 
the N/NW direction. The survey team continued north on FS100, and additional tree 
branches and smaller pine trees were uprooted. Progressing farther north along FS100, 
tree damage became more widespread and severe with degree of damage indicators increasing 
as more snapped softwood pine trees were cataloged and noted. This portion of FS100 
decreases in elevation and into a narrow localized valley along Turpin Creek to the north 
and northwest. A vantage point at the south end of the valley, higher in elevation,
allowed for a landscape view towards the main tree damage path. This enhanced visual
perspective allowed the survey team to see east-northeast uprooted and bent
softwood pine trees. There were also snapped pine trees down the main center line of the 
damage path oriented to the north to north-northwest, and softwood pine trees to the east
of the main centerline, converging back to the west to northwest. It was noted the
greatest tree damage on the south to middle portions of the local Turpin Creek Valley. 
This damage was located along the west side of FS100, crossed FS100, with the greatest 
snapping to the East as one progressed farther north along FS100. This evidence indicated 
the tornado crossed FS100 in following the main snapping of tree damage along with the 
notable convergent pattern of tree fall. From the south side of the local Valley, tree damage
extended at least 100-200 yards west of the road, with a wider damage swath noted to the east 
of FS100 as one progressed farther north. The damage swath of uprooted and snapped
trees east of FS100 was approximately 200-300 yards from the road. The damage area
narrowed substantially and became indiscernible as the team progressed north towards
Bow River Campground near the intersection of FS100 and FS101. The end point was 
marked at the north end of a concentrated area of tree debris, small tree uprooting, and 
dislodged branches at an elevation around 9000 feet.

It should be noted that sporadic tree damage was also noted both southwest and northwest of
the main track and the concentrated damage area. Sporadic softwood pine uprooting was noted
along FS100 just north of HWY 130, but showed no conclusive evidence of a converging pattern. 
Likewise, FS105, FS120, and FS111 also had sporadic trees down, but once again, all trees fell
in a northerly direction. The uniform direction suggested straight-line winds were
the likely culprit of this tree damage. 


Rating:                 EF-1
Estimated peak wind:    105 MPH (Mostly 90-100 MPH)
Path length /Statute/:  1.21 miles
Path width /Maximum/:   600 yards
Fatalities:             None
Injuries:               None

Start date:             JUN 06 2020  
Start time:             2:51 PM MDT
Start location:         14 miles southwest of Arlington, WY
Start Lat/Lon:          41.4594 / -106.4015

End date:               JUN 06 2020
End time:               2:57 PM MDT
End location:           13 miles southwest of Arlington, WY
End_lat/lon:            41.4750 / -106.3982

EF Scale: The Enhanced Fujita Scale Classifies
Tornadoes into the following categories.

EF0...Weak......65 to 85 mph
EF1...Weak......86 to 110 mph
EF2...Strong....111 to 135 mph
EF3...Strong....136 to 165 mph
EF4...Violent...166 To 200 mph
EF5...Violent...>200 mph

The information in this statement is PRELIMINARY and subject to
change pending final review of the event and publication in
NWS Storm Data.