The evolution of two tornadic supercells into an intense bow echo over southwest Nebraska and northwest Kansas

Convective storms can take on many different types of characteristics as they move in space and time across varying environments of moisture, wind, and temperature. From these basic environmental parameters, you have various derived parameters that are directly and indirectly derived from these variables. Such examples of derived parameters would be Convective Available Potential Energy (commonly known as CAPE) which is a measure of an air parcel's ability to rise on its own without the help of other forcing mechanisms at the surface or aloft. Temperatures, lapse rates, moisture flux, and wind shear/helicity would be examples of a few others. When changes occur with these parameters and variables over space and time, convective processes themselves can take on different modes as storms transverse across different environments.

This paper will document such an unusual event that occured over southwest Nebraska and northwest Kansas where thunderstorms developed in a supercellular enviroment over one portion of the Goodland, KS County Warning Area (CWA) containing tornadoes and large hail, then moved into a rapidly changing enviroment where higher moisture and low level southerly flow lead to higher instabilities and thus a change in storm type/structure with damaging straight-line winds, heavy rainfall and continued hail threat. This paper will present similarities to the 1994 Lahoma, OK event documented by Conway (NSSL). In addition, thermodynamic parameters, mesoscale/synoptic contributors,Goodland WSR-88D signatures of both the mesocyclonic and bow echo stages and resultant damage thereof will be discussed.