Wednesday, 5 November 2014
Capitol Ballroom AB (Madison Concourse Hotel)
A long-duration tornado outbreak evolved from the eastern Plains states to the Carolina coastal plain during the period of 27-29 April 2014. At least 75 tornadoes were reported over this period, with 34 direct tornado fatalities. The epicenter of this damaging tornado outbreak was over central and eastern Mississippi, northern and central Alabama, and southern middle Tennessee from the evening of 28 April to the predawn hours of 29 April, where over 50 tornadoes were recorded. Many of these tornadoes were strong to violent intensity (EF2-EF4 on the Enhanced Fujita Scale). Thirteen of these tornadoes occurred within a high-density observational array across the Tennessee Valley region of northern Alabama and southern middle Tennessee. The first tornado occurred at 2047 UTC, and the last tornado ended at 0826 UTC, with severe weather activity occurring nearly continuously throughout the 10.7 hour window. In this presentation, we review several important observations recorded during this outbreak. We show high-resolution data from the University of Alabama in Huntsville (UAH) Mobile Alabama X-band (MAX) dual-polarimetric radar of tornadogenesis of the first Tennessee Valley tornado of the outbreak in northwest Alabama, the first such active interception of a tornado in northern Alabama. Additionally, we discuss a series of interactions between the Coxey-Athens, AL, EF3 tornadic supercell and several quasi-linear reflectivity segments that have been observed with tornadogenesis events in the past were observed immediately prior to tornadogenesis. These interactions were observed immediately prior to rapid intensification of the tornado using the UAH Advanced Radar for Operational and Meteorological Research (ARMOR). Finally a transition of the near-storm environment and supercell characteristics during the afternoon-evening transition and potential terrain influences on several of the nighttime tornadoes in northeast Alabama will be discussed.
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