ESRL/PSD Seminar Series

Abstract

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In recent years, research on tropical cyclone (TC) recurvature and extratropical transition (ET) has broadened to include investigation of the impact of TC recurvature and ET on the downstream large-scale flow pattern. Case studies and idealized modeling studies have illustrated that the outflow of a recurving TC impinging upon a midlatitude jet stream can excite and amplify a Rossby wave train. However, the factors that modulate the Rossby wave response to a recurving TC are not well known. Understanding the Rossby wave response to recurving TCs over the western North Pacific (WNP) is critical because (i) Rossby wave trains migrating from the Pacific are known precursors to large-scale flow reconfigurations and high-impact weather events over North America, and (ii) Rossby wave trains associated with recurving WNP TCs may contribute to reduced predictability over North America.

The aim of this study is to examine the factors that modulate the downstream flow response to recurving WNP TCs. Composite analyses will be used to illustrate the physical processes involved in the excitation and amplification of Rossby wave trains associated with recurving WNP TCs, as well as the characteristic impact of such wave trains on the large-scale flow pattern over North America. Additionally, a case study will be presented of a recent recurving WNP TC (Lupit, October 2009) that led to the onset of a high-amplitude trough, widespread heavy precipitation, and a period of reduced predictability over the U.S.

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