Mobile mesonet observations of an intense RFD and multiple RFD gust fronts in the May 23 Quinter, Kansas tornadic supercell during TWISTEX 2008

There are many unresolved issues regarding tornadogenesis in supercells. One question that has received recent attention in the research community is the role of the rear-flank downdraft (RFD) and rear-flank downdraft gust front (RFDGF) in tornadogenesis. Project TWISTEX 2008 (Tactical Weather Instrumented Sampling in/near Tornadoes Experiment) was a field experiment designed to collect near-surface data in and near tornadoes. One of the project objectives was to document the kinematic and thermodynamic environment in the vicinity of the RFDGF, and to try to determine the RFD/RFDGF's contribution to low-level mesocyclogenesis, tornadogenesis and tornado maintenance.

On 23 May 2008, three TWISTEX mobile mesonet teams intercepted a tornadic supercell south of Quinter, KS. Teams followed the storm north as it cycled, and collected high-resolution data across the RFDGF and within the RFD a few miles north of Quinter just prior to, and during the development of a mile-wide tornado. Of specific interest, the mesonet sampled a very strong internal RFD surge boundary that appeared temporally related to the formation of the large tornado.

A preliminary analysis of the data revealed several interesting features as the RFD passed over the mesonet array, including strong vortices along the internal RFD surge boundary, one of which passed directly over a mobile mesonet station. Wind speeds in excess of 90 kt were measured along the leading edge of the surge. Following the passage of the internal RDF surge boundary the temperature and dewpoint increased gradually to values differing only slightly from the storm inflow. An analysis of high resolution kinematic and thermodynamic data will be presented, and the implications for tornadogenesis will be discussed.