6.1
Tornadogenesis, maintenance, and demise in the Dimmitt, TX storm
Erik Rasmussen, CIMMS/Univ. of Oklahoma and NOAA/NSSL, Boulder, CO; and J. Straka
The most significant observations of the Dimmitt, TX tornadic storm of 2 June 1995 are examined in detail. Tornadogenesis proceeded through several stages. First, part of the bounding echo cap descended to the rear of the updraft, forming a ribbon-like echo appendage with an embedded reflectivity maximum. This reflectivity maximum was associated with a local downdraft, and a cyclonic-anticyclonic vortex pair straddled the downdraft/appendage feature. About 1500 m ahead of this elevated but descending vortex pair, a wave developed on the rear flank gust front, with large cyclonic vertical vorticity near the ground. The elevated cyclonic vortex became colocated with the gust front wave, while the anticyclonic member was drawn around the intensifying tornado cyclone. Tornado formation occurred as the gust front wave and developing tornado cyclone became completely occluded.
The angular momentum budget of the Dimmitt tornado as estimated from mobile Doppler radar, as well as the morphological features and evolution associated with various changes in the angular momentum field, will be documented in order to gain insight into the maintenance and demise of the tornado.
Session 6, Observations of mesocyclones and tornadogenesis
Thursday, 13 January 2000, 8:00 AM-10:00 AM
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