Short Contribution Genesis of the Chickasha, Oklahoma, Tornado on 24 May 2011 as Observed by CASA Radar and Oklahoma Mesonet

On the afternoon of 24 May 2011, a dozen tornadoes formed across central Oklahoma that included one EF-5 and two EF-4 tornadoes. One of the EF-4 tornadoes developed in the city of Chickasha, Oklahoma, and was well sampled by a nearby Collaborative Adaptive Sensing of the Atmosphere (CASA) X-band radar. Located within 3 km range, the CASA radar obtained low-level (~100 m AGL), high-spatial (~100 m), hightemporal (60 s) sampling data at the time of tornadogenesis. In addition, an associated boundary was sampled by two Oklahoma Mesonet sites located within 5 km of tornadogenesis. Analyses of the radar imagery and surface data revealed that interaction of the boundary with the low-level mesocyclone may have contributed to tornado initiation. The coiling boundary and subsequent tornadogenesis were not sampled by the nearest WSR-88Ds (located 70 km and 119 km away). This event demonstrates how local, supplementary sensor networks, such as high-resolution radars and surface mesonets, can improve situational awareness and confidence for the operational forecaster during a hazardous weather scenario.