Wednesday, 13 October 2010
Grand Mesa Ballroom ABC (Hyatt Regency Tech Center)
The Polarimetric Radar for Innovations in Meteorology and Engineering (OU-PRIME) captured a rare dataset on 10 May 2010, obtaining high-resolution polarimetric radar measurements in multiple supercells and numerous tornadoes. One supercell moved east from Norman, Oklahoma producing at least four tornadoes, including one EF-3 and one EF-4 tornado. The life cycle of this supercell was characterized by interactions with a supercell to the north, which produced an EF-3 tornado. One striking observation of this dataset is the genesis and maintenance of strong tornadoes with two supercells in proximity and precipitation from the southern supercell falling into the inflow region of the northern supercell. The rear-flank downdraft (RFD) gust fronts of the northern and southern supercell remained separated initially, providing a sufficiently large region for inflow into both supercells.
Storm mergers and the interactions between the RFDs were important throughout the life cycle of the observed tornadoes. A weak convective storm entered the inflow region of the southern supercell just before the southern tornado dissipated. At about the same time, the RFD of the southern supercell filled with precipitation, and the RFD gust fronts of the northern and southern supercells merged. Consequently, the southern tornado dissipated while the northern tornado persisted because the surging RFD did not affect the northern supercell's inflow. During tornadogenesis of the final EF-3 tornado, two storm mergers occurred with the primary supercell. The relevance of the storm mergers will be discussed, emphasizing how the merger process aided or inhibited tornadogenesis.
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