An anticyclonic tornado observed 10 May 2010 with CASA radar

The Center for Collaborative Adaptive Sensing of the Atmosphere (CASA) is a National Science Foundation Engineering Research Center funded with the objective to create low-power, low-cost, short-range (X-band) radars that can be deployed on cell-phone towers. Multiple CASA radars are deployed collectively, together comprising an integrated network with radars operating collaboratively and adaptively. A demonstration testbed of four CASA radars was deployed in Oklahoma in 2006, and since that time has operated each spring and fall during convective events. Each radar has a range of 40 km, a bandwidth of 1.8 degrees, dual-polarization capability, and rapid, adaptive sampling (update rate of 60 sec).

On 10 May 2010 an anticyclonic tornado formed within an anticyclonic supercell near the town of Bray, Oklahoma. The storm formed east of an approaching dryline, and among 31 documented tornadoes that afternoon and evening across central Oklahoma and Kansas, was one of several mesoanticyclones observed that day. The tornado moved northeastward through Stephens and Grady Counties for approximately 10 minutes. The total damage path was estimated at 6 miles long with a width of 700 yards; the NWS estimated the storm intensity as EF1. One-minute volume scans of the storm were collected by the KRSP CASA radar, and Level 2 Doppler and dual-polarization data were archived. Gate-to-gate shear of 50 ms-1 was observed with the vortex at 400 m AGL, and a clear hook was visible in the associated reflectivity. This event is believed to be among the best observed anticyclonic tornadoes recorded, particularly of this magnitude from an anticyclonic thunderstorm, and is compared to previous events in the literature.