Monday, 11 October 2010
Grand Mesa Ballroom ABC (Hyatt Regency Tech Center)
Landfalling tropical cyclones (TCs) are known to produce embedded supercells, some of which are tornadic. This study investigates the role of midlevel dry air intrusions and the sea-to-land transition on intensifying these embedded supercells. We hypothesize that storm-scale processes that lead to updraft rotation are enhanced in supercells that develop in and near dry air intrusions due to localized midlevel evaporational cooling in the typically moist TC environment and cloud erosion, which leads to increased surface insolation during the day. We also hypothesize that the sea-to-land transition is a crucial factor in TC supercell intensification due to the impacts of (1) a larger diurnal temperature variation, and (2) increased surface friction, which lengthens the hodograph in the TC's right-front quadrant. These hypotheses are tested using the Advanced Research WRF (WRF-ARW) model. In our quasi-idealized simulations, supercells form naturally in the rainbands of a credible TC. Our extended abstract and conference presentation will document a series of experiments testing the sensitivity of embedded TC supercells to an idealized midlevel dry air intrusion and to a variety of TC landfall scenarios.
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