Discriminating between Tornadic and Non-Tornadic Supercells: A New Hodograph Technique

摘要: Thompson and Edwards (2000) first noted a prominent hodograph kink separating primarily speed shear from directional in the environments of some supercells producing significant tornadoes. Responding to this observation, we compared similar thermodynamic between Moore, Oklahoma tornado 3 May 1999 non-tornadic supercell thunderstorms occurring north Texas on 23 April 2003. The results suggest that certain characteristics could discriminate tornadic supercells. This combination features consisted strong (> 10 m s -1 ) nearly straight-line below 500 above ground level (AGL) storm-relative inflow orthogonal base segment at m, yielding almost purely streamwise inflow. We evaluated hypothesis by analyzing 67 severe convective events, 65 which were supercells, 1997-2004, dividing events into non-tornadic, weak-tornadic (F0-­F1), significant-tornadic (F2-­F5) storm classes. show improved discrimination classes for 10-­500 helicity bulk magnitude when 10-­1000 calculations same. Also, histograms critical angle (defined vector vector) revealed storms, particular tended be characterized angles near 90°, whereas storms not. Although are based relatively small sample, they careful consideration evolution low-level both time space relation motion can potentially valuable aid forecasting