Extended Abstract (1.1M)15A.6
Regions of intense convection in the core of minimal tropical cyclones
Daniel E. Lipper, University at Albany/SUNY, Albany, NY
Cloud to ground lightning flash data from the National Lightning Detection Network (NLDN) were used to pinpoint convective outbreaks in the hurricane core (r < 100km). ECMWF gridded analyses were used to calculate vertical wind shear values in the same storms. An attempt will be made to understand the processes responsible for prolonged convective episodes. Three tropical cyclones, Bob (1985), Earl (1998), and Harvey (1999) contained intense periods of convection in their core. At the time of these outbreaks, all three storms were of tropical storm status. The peak convective episodes exhibited a strong downshear preference. This large asymmetry is apparent when viewing the storms on satellite imagery. Harvey featured over 1,900 strikes confined to a relatively small area in a one hour period. The outbreak in Bob was more long-lasting, with over 200 strikes in eleven consecutive hours. The coexistence of rainfall rates of 30 to 55cm in 24 hours with this outbreak, definitely render it of operational significance.
In the talk, the conditions that favor intense convective cells in the core of tropical cyclones will be examined. The role of such outbreaks in tropical cyclone intensity change will be discussed.
Session 15A, Tropical Cyclone Observations and Structure IV (Parallel with Sessions 15B and 15D)
Thursday, 2 May 2002, 4:00 PM-5:30 PM
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