Mobile, phased-array, doppler radar observations of tornadoes at X band

Amobile, phased-arrayDoppler radar, theMobileWeather Radar, 2005 X-band, PhasedArray (MWR-05XP), has been used since 2007 to obtain data in supercells and tornadoes. Rapidly updating, volumetric data of tornadic vortex signatures (TVSs) associated with four tornadoes are used to investigate the time-height evolution of TVS intensity, position, and dissipation up through storm midlevels. Both TVS intensity and position were highly variable in time and height even during tornadomature phases. In one case, a TVS associated with a tornado dissipated aloft and a second TVS formed shortly thereafterwhile there was one continuousTVS near the ground. In a second case, the TVS associated with a long-lived, violent tornado merged with a second TVS (likely a second cyclonic tornado) causing the original TVS to strengthen. TVS dissipation occurred first at a height of;1.5 km AGL and then at progressively higher levels in two cases; TVS dissipation occurred last in the lowest 1km in three cases examined. Possible explanations are provided for the unsteady nature of TVS intensity and a conceptual model is presented for the initial dissipation of TVSs at ~1.5 km AGL.