Rapid-Scan DOW radar observations of tornadoes during VORTEX2

The rapid-scan Doppler on Wheels (DOW), a 6-beam, multi-frequency passive phased array radar, is capable of simultaneously collecting 6 levels of data in less than 10 seconds. A 2.5 m square slotted waveguide antenna produces a 0.8° beam. Range resolution as fine as 25 m is possible with short pulses and radar gating. This capability makes the rapid-scan DOW ideally suited to study rapidly evolving phenomena, such as tornado vortices. During the VORTEX2 2009 season, the rapid-scan DOW collected data during the 5 June 2009 Goshen County, WY tornado. The tornado passed within 400 m of the DOW. Over 30 minutes of continuous data were collected. Volumetric data were collected every 7 seconds, yielding over 250 volumes of tornado data with simultaneously fine-scale spatial and temporal resolution. The early stages immediately after genesis, intensification and demise of the tornado were documented from 2202 UTC to 2234 UTC. The rapid evolution of the structure and dynamics of the tornado are analyzed. Data from the rapid-scan DOW are interpreted in the context of traditionally produced dual-Doppler analyses from DOW6 and DOW7. Dual-Doppler analysis using the 7-second updates of the Rapid-Scan DOW and the 1 minute low level updates of the DOW7 will be presented. During the 2010 VORTEX2 season, data in several tornadoes were collected with the Rapid-Scan DOW, some in configurations which permit dual-Doppler analysis. Preliminary results from these analyses will be presented.