OBSERVATIONS ON THE ORIGINS OF ROTATION - THE NEWCASTLE TORNADO DURING VORTEX 94

Observations of a strong (F3) tornado near Newcastle, Texas, on 29 May 1994 during the Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX) are presented. The visual characteristics and inte nsity of the tornado were revealed by a photogrammetric analysis of pi ctures taken by chase teams and by a detailed damage survey. The torna do developed from a low-level shear feature along the flanking line of a supercell. Vortex stretching of this feature to tornadic intensity occurred under the influence of an intense updraft from a rapidly grow ing storm along the flanking line. No apparent midlevel mesocyclone ac companied this tornado. In contrast, the supercell was characterized b y a well-defined mid- and low-level mesocyclone; however, no tornado w as observed by ground chase teams. The implications of these findings on the current understanding of tornadogenesis are discussed.