92nd American Meteorological Society Annual Meeting (January 22-26, 2012)

Wednesday, 25 January 2012: 8:30 AM
Radar Overview and Visual Documentation of the 27 April 2011 Tornadic Outbreak
Room 252/253 (New Orleans Convention Center )
Todd A. Murphy, University of Alabama in Huntsville, Huntsville, AL; and T. A. Coleman, R. A. Wade, and K. R. Knupp

A historic severe weather outbreak devastated much of the southeastern United States between 25 and 28 April 2011. Central and north Alabama were hit especially hard by tornadoes on 27 April, including nine that were rated as EF-4 and EF-5 on the Enhanced Fujita (EF) scale. These tornadoes occurred during three separate episodes of severe weather that day, an early morning quasi-linear convective system (QLCS) with an embedded mesoscale convective vortex (MCV), a mid-day QLCS, and finally a sequence of supercell thunderstorms in the late afternoon and early evening.

Multiple tornadoes from this event occurred within range of several radars located in or near Alabama, including WSR-88Ds and two UAHuntsville research radars, the Advanced Radar for Meteorological and Operational Research (ARMOR, C-band dual-polarimetric) and the Mobile Alabama X-band (MAX, dual-polarimetric) radar. The tornadic mid-day QLCS that traversed north Alabama was well sampled by the instrument suite on board the Mobile Integrated Profiling System (MIPS), including high temporal measurements (6 Hz) of a bounded weak echo region (BWER) and distinct horizontal rolls in a strong gust front by the vertically pointing X-Band Profiling Radar (XPR). Additionally, the tornadoes (primarily those in the afternoon) were extensively documented by the public in the form of photographs and video; these items are being collected and verified by personnel at UAHuntsville.

The intent of this presentation is to give a general overview of the events that occurred on 27 April in Alabama and bordering states, mainly focusing on radar imagery and the integrated measurements from MIPS. Some compiled statistics of where this event ranks compared to past events will be also be presented. Finally, the collected visual documentation will be shown alongside the associated radar data for comparisons. This combination of radar data and visual documentation from multiple tornadoes in such a high impact outbreak produced a highly unique dataset and allows for a very interesting analysis on this wide range of tornadic storms.

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