April 30, 2004 - Oklahoma - Texas


  
Chase Account by: Jonathan Garner
  
...First off, thanks to Jared Guyer for the great nowcasting he provided during this chase...

Brian Thalken, Jim Kaiser and myself left Lincoln at 6am. Our target was an area from Wichita Falls, TX south to Abilene, TX. We arrived in Oklahoma City by 12:30pm, and then made our way southwest toward Wichita Falls on I-44. At 1:45pm, we spotted a large cell developing to our south (we had just passed through Lawton, OK). This cell was moving east along the Red River...it had a huge back sheared anvil, and the updraft tower on the flank of the storm was rock hard. In addition, this developing storm was moving along an outflow boundary, which could be a potentially significant ingredient for tornadogenesis later in the day. At 2:05pm, we exited I-44 and went east on highway 70, which follows the north side of the Red River. The NWS had just issued a tornado warning for our cell, with spotter reports of funnels and a possible touchdown on the Texas side of the border. We were on the north side of the cell, so we would have to punch through the core in order to reach the tornado warned part of the storm...so, we turned south on highway 81, heading for the town of Ryan, OK. The heavy rain and small hail we occasionally encountered soon cleared off as we blasted south through the forward flank downdraft, and soon, we could spot a rain free base with an incredible shelf/wall cloud type feature towering above it.
This storm was strongly rotating, with large amounts of scud getting sucked into the wall cloud from the forward flank outflow boundary. We parked and observed this cell as it moved east toward the town of Ryan, OK, but we soon realized that we needed to retreate eastward ourselves as the rotating wall cloud was about to overtake our position. By 2:50-3pm, we had repositioned ourselves about 5 miles further east, just in time to observed the low-level mesocyclone really get its act together. It appeared that an RFD was beginning to descend around the area of low-level rotation, which caused that area of rotation to rapidly intensify. The wall cloud was being fed by a strong tail cloud/inflow band as it began to take on a circular appearance. The RFD expanded eastward and northward, and then wrapped around the center of strongest rotation back to our northwest. This storm was so close to producing a tornado, but then, as our nowcaster Jared Guyer soon informed us, another cell back to the west was beginning to merge with ours...effectively dumping its precipitation into our updraft and most likely killing the tornadic potential of our storm. After this cell became outflow dominant, we decided to target other storms further to the south, but by this time, too much lift in the presence of too little capping resulted in multiple updrafts in every direction and a low to mid-level cloud deck which decreased instability as well as visibility. The fist cell of the day was our window of opportunity, but it failed to produce...but the storm was still very exciting to watch and made the chase worth-while.