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Information on
the Winslow Tornado
Shortly before 1 PM MST on September 29th, 2004 a small
tornado touched down to the east of Winslow, AZ over open terrain for
about 15 minutes. This tornado was produced by a severe thunderstorm
that tracked just to the east of Winslow along Interstate 40. This
tornado was witnessed by many in and around the city of Winslow and
along Interstate 40. The images below have been provided as
a courtesy from the Arizona Department of Transportation,
and were taken at Milepost 262 on I-40.
This storm was closely tracked by forecasters at NWS Flagstaff with
the WSR-88D doppler radar.
Scans from the Blue Ridge WSR-88D of the 0.5 degree reflectivty
scan can be viewed here. The orange
and red areas are indicators of higher precipitation rates and possible hail.
A loop of the storm relative motion velocity data from the 0.5 degree slice
can be viewed here. The red
coloring shows storm relative velocities moving away
from the radar. The green colors indicate wind flow moving toward
the radar. In several of the images of this storm relative motion
velocity loop, a “Tornado Vortex Signature” is evident
(TVS). The TVS in this loop can be identified in the areas where a
40 KT outbound velocity are directly adjacent with a 40 KT inbound
velocity. A TVS indicates a strong circulation occurring within the
storm. TVS's usualy only span only 2 or 3 pixlels of an image, so a
sharp eye is needed by the forecaster to pick them out. Luckily, the
computer processing capabilities of the WSR-88D can aid forecasters
in this endeavour. Can you see where the TVS occurs in the loop?
The TVS on this imagery sequence prompted NWS forecasters at NWS
Flagstaff to issue this Tornado Warning.
Click each image to see a
larger view.
These radar images are from about the same time the above snapshots were taking along Interstate 40. (Click each image to enlarge)
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0.5 degree Reflectivity at 12:54 PM MST
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0.5 degree SRM at 12:54 PM MST
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