Merging Supercells and Tornado
Tulia Texas 21 June 2004


During the last evening hours of June 21st a very severe supercell thunderstorm moved south out of Amarillo Texas along Interstate 27. The storm had a history of high winds, numerous brief tornadoes and hail over 4 inches in diameter. Lying in the path of this storm was a couple of small low precipitation supercell. Many times the merger of supercells can bring the onset of tornadic activity. In this particular situation the storm approaching from the north had a strong gust front with winds stronger than 60 MPH. The question was, can the small storms produce a tornado before the outflow winds from the north storm sweep under them, thus cutting off all inflow to the growing updrafts.


All images and text
© copyright Gene Moore


Approaching supercell along I-27 at mile marker 86. The lower dark clouds were very turbulent and responsible for spinning up numerous gustnados. One such funnel is shown in the frame and later spun up a large dust cloud, although not counted as real tornadoes, they do tend to scare those in their path. The menacing appearance kept spotters and chasers fixed on the north storm, it was also the source of all the current warnings.



North supercell dropping south from Amarillo begins to draw in material from small supercell over Tulia. Long streamers of cumulus poured into the outflow of the north storm. Although still daylight these towers were full of intracloud lightning.


Looking to the southeast with a wide angle captures a wall of rock hard updrafts streaming north-northeast into the approaching storm. Hey, these things were tall, but that wide angle lens makes them look little-bitty.



Lot's of rock hard convection feeding into a point to my east. I thought I should get over there but that nasty gust front was coming down from the north....decisions .....decisions.


Meanwhile to the south another small supercell is developing. This is so complicated, do I go south or east. Then looking east a multivortex dirt whirl developed heading northeast. I made a beeline for the next exit.



Oh rats, too late, very good tornado, better than it looks here. The area all around the funnel was rotating. I should have been about two miles east, but no road where I needed it.


Watching it fade behind a rotating rain curtain is no fun. Also, I got this new digital camera and in low light it's a pain to get set. The focus keep going somewhere it shouldn't be. Anyway, while I'm jacking with the camera the tornado is going somewhere else, leaving me behind. I finally got these shots.



This was the last storm of the day and it was beautiful with spectacular anvil to ground bolts on the south side. It was an outstanding updraft with boiling towers shearing into the anvil canopy. As I drove under the optical vault to my south I expect some large hail, but all I got was terrific inflow winds, really rocked the vehicle bad. After that I setfor the sunset while watching base rotate. It produced a shallow cone funnel and rotating dust cloud. I almost got another tornado, then the roaring gust front swept through from the north storm. It put and end to the rotation very quickly.


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