NSSL SWAT Case Study - 11 June 1997 Texas Panhandle

Several supercells occurred in the Texas Panhandle on this day.  Wheeler county was hardest hit when a mile wide F3 tornado tracked from just southeast of Kellerville across Interstate 40 to just southwest of Lela.  Softball size hail was observed in Shamrock from the core of this tornadic storm.  Other storms produced brief tornadoes and severe hail throughout the evening.

June 11 1997, presented an interesting lesson in tornado formation.  The Kellerville F3 tornado formed in classic, predictable fashion, beginning with broad mid-level rotation which built its way down to the storm base.  A strong rear flank downdraft ultimately brought the circulation to the ground, a mile wide and shrouded in precipitation.
Meanwhile, only some 20 miles to the south of Kellerville and not long after the dissipation of that tornado, the author of this page witnessed a smaller, more tube-like tornado nearest to Dozier.  The Dozier tornado developed from a much higher storm base, and well away from the precipitation.  The parent circulation did not extend to the mid levels of the storm, and it originated at the storm base before working its way up (opposite the Kellerville tornado).  These two tornadoes, having taken place in close proximity at nearly the same time illustrate how distinctly different mechanisms are at work in the development of tornadoes.  Researchers have their hands full attempting to identify those mechanisms.

Presented here are various WSR-88D radar images from the Amarillo, TX radar (KAMA).  Included in some of the images is output from NSSL's Mesocyclone Detection Algorithm (MDA). A yellow circle depicts a mesocyclone.  A red-in-yellow circle  indicates the mesocyclone extends to the lowest elevation scan of the radar (extists near or ar the base of the storm) where it is a more likely tornado threat.

Description:  There are several things to note from the F1 Tornado-Reflectivity scan.  At the time of the scan, the Dozier tornado was in progress and was associatied with the high-based mesocyclone #451.  The surface-based mesocyclone #278 would seem a more likely tornado candidate in the classic sense, but it produced only a brief tornado.  The Dozier tornado persisted for six minutes.

Also of note is mesocyclone #299.  This is what remained of the Kellerville tornado which lifted at 0032 UTC.  The development of the Dozier storm disrupted the southwesterly inflow into the Kellerville tornado.  Had this not taken place, the Kellerville tornado may very well have maintained itself.  As it stood, the Kellerville tornado tracked 9 miles over 46 minutes.

The Storm Relative Velocity Cross Section is interesting to compare with that of the Kellerville tornado (See previous discussion).  It is quite clear from these images that the Kellerville storm exhibited deep rotation whereas the Dozier tornado was quite shallow.
The entire parent storm of the Kellerville tornado was rotating (green-inbound velocities  meet  red-outbound velocities) up to about 28 thousand feet.  Rotation with the Dozier storm really can only be seen at storm base.  The bright green-inbound velocities at the bottom center of the inage represent strong storm outflow.  This outflow slopes downward until it is interupted by a thin column of red-outbound velocities.  This red column was the tornado.  Indeed, the tornado was visually observed to be forced westward by outflow at the ground.  Aloft, the tornado reached back toward the east, over the outflow.          

Description: Wellington endured severe storms for nearly three hours. When this line of storms bowed out in a comma shape, two tornadoes occured in the storm at the comma head.

Learn more about this event on Greg Stumpf's Page.
Learn more about this event on Kevin Scharfenberg's Page
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