HR: 09:20h
AN: PP51A-05 INVITED     [Abstracts]
TI: Tropical Cyclogenesis and Motion in the Eastern North Pacific
AU: * Zehnder, J A
EM: zehnder@asu.edu
AF: Arizona State University, PO Box 873211, Tempe, AZ 85287-3211, United States
AB: The East Pacific, north of 10oN latitude and adjacent to the west coast of Mexico, experiences one of the highest rates of tropical cyclone formation in the world. These storms tend to develop rapidly and while most of them are relatively weak (category 3 or below), they pose a significant hazard in the coastal regions of Mexico and to shipping. Also, the rapid development requires an ability to forecast the genesis of the cyclones in addition to the track and intensity, in order to provide adequate lead times for warnings. Our current understanding states that easterly waves that develop over Africa and propagate into the region serve as the seedlings of the East Pacific tropical cyclones. There are a number of open questions such as the way the waves remain coherent in the presence of Rossby dispersion. Also, the mechanism through which the waves intensify into tropical cyclones in the preferred location must be identified. One possibility is that a modification of the waves by the orography of Mexico and Central America, along with contributions from the Inter-tropical Convergence Zone provides the mesoscale circulations that develop into tropical cyclones. This talk will describe mechanisms for generating the initial circulations that develop into tropical cyclones in the East Pacific, along with a discussion of the influence of the land mass on the track of the mature storms. The influence of the East Pacific tropical cyclones on the summer climate of North America will also be discussed. These storms act as sources of moisture for thunderstorm outbreaks in the low deserts of Arizona through a mechanism known as the Gulf Surge.
DE: 3332 Mesospheric dynamics
DE: 3364 Synoptic-scale meteorology
DE: 3374 Tropical meteorology
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Joint Assembly