A Storm-Scale Analysis of the 29 May 2013 Tornado Event across East-Central New York
Observational data, as well as short range deterministic Rapid Refresh data suggested a significant severe weather outbreak would occur. Much of the impacted area had just entered a warm sector with a warm front just north of the Mohawk Valley and Greater Capital Region. Upstate NY and New England were situated near the right entrance region of a 250 hPa 85 kt jet streak with an approaching strong upper level short-wave for the afternoon. A moderate instability and high shear pre-convective environment was in place before the severe weather. Surface based convective available potential energy values ranged from 500 to 1500 J kg-1 with increasing effective bulk shear values of 35 to 50 kts. 0-1 km Storm-Relative Helicity values were in the 150-200 m2 s-2 range. The effective bulk shear values in the 0-6 km layer suggested the possibility of supercells with rotating updrafts capable of producing large hail and tornadoes.
This presentation will focus on a detailed radar analysis of the event, utilizing the new dual polarization data (differential reflectivity, correlation coefficient, and specific differential phase). The impressive tornadic debris signature will be shown with the correlation coefficient data showing debris detected up to 6200 ft AGL. Traditional base and derived WSR-88D radar products will also be shown in conjunction with the Dual-Pol data. The storm-scale analysis will focus on helpful forecast techniques, including applying results from a local rotational velocity (V)-shear study, to determine what caused the tornadoes and how the tornado warning process can be improved.