Tuesday, April 29, 2014

Analysis of the Tupelo Tornado on April 28, 2014

On April 28th, 2014, a supercell moving northeast across northern Mississippi became tornadic, and exhibited multiple signals of a large, violent tornado before it struck Tupelo, MS.

At approximately 2:44 PM Central Time/3:44 PM Eastern Time, radar indicated a supercell with a defined hook echo signature located in the immediate vicinity of Tupelo, as indicated above. This supercell was exhibiting a tornado debris signature (TDS) at the time it struck Tupelo, indicating that a tornado was already on the ground and doing damage. The already-dynamic environment, which later warranted a rare 'High Risk' of severe weather designation by the Storm Prediction Center, provided a sustaining mechanism for this tornadic supercell which eventually did strike Tupelo.

At approximately 2:54 PM Central Time, or 3:54 PM Eastern Time, the supercell had now moved past Tupelo. Radar imagery indicated a much more defined TDS, culminating into the appearance of a debris ball, in which a tornado is present and is throwing debris high up into the air, which then appears on radar. Note that the debris ball is significantly more defined at 3:54 PM in comparison to the previous radar scan at 3:44 PM. This development, combined with further analysis which detailed a more specific track, eventually led to the realization that this tornado had directly hit the city of Tupelo, Mississippi.

The correlation coefficient, a tool of dual-polarization radar, also indicated the presence of a debris ball. Using two methods of scanning from the radar tower, the radar is able to pick up the likelihood of a debris ball. When looking at a correlation coefficient (CC) chart above, one would want to observe values below 0.800 or so (seen as blues on this chart) to identify a potential debris ball. As this CC image from 3:54 PM ET shows, the debris ball is clearly evident in the white circle, seen as a deep blue dot. This nearly confirmed the possibility that this tornadic supercell had struck Tupelo, producing significant damage.

According to the governor of Mississippi, 131 homes and numerous businesses had been damaged in Tupelo as a result of this tornado. Dozens of injuries were reported as a result of this storm, but none were told as life-threatening.

Additional analyses of other tornadic supercells will be released in coming days.