18th Conference on Weather and Forecasting, 14th Conference on Numerical Weather Prediction, and Ninth Conference on Mesoscale Processes

Thursday, 2 August 2001
Development of Tropical Cyclone Potential Intensification Index
Gabriel S. Rothman, Plymouth State College, Plymouth, NH
This paper proposes a new forecasting scheme for tropical cyclone potential intensification through the use of an index. This index is somewhat similar to the application of the moisture and stability indicies used in the current conventions of thunderstorm forecasting. The main objective of this endeavor is to obtain a useable formula that will provide forecast guidance on tropical cyclone intensification. In this scheme, values of negatively and positively contributing parameters to tropical cyclone intensification downstream from the center of circulation would be directly formulated together to obtain a result. The result would be classified within a designated range that would indicate the disturbance's potential intensification based upon it's present environment. The parameters used in this formula would be representative of the conditions at the ocean's surface and the atmosphere above. Since the values for negatively contributing parameters would be subtracted and values for positively contributing parameters would be added in the formula, the value of the result will be directly proportional to the potential for intensification of the tropical disturbance being examined. The following formula is a preliminary example of a possible Tropical Cyclone Potential Intensification Index (TCPII):

TCPII=Sea Surface Temperature + 1000mb Ambient Relative Humidity + 500mb Ambient Relative Humidity - Tropopause Pressure Height - Absolute(200mb Wind Speed - 850mb Wind Speed) - Absolute(200mb Wind Direction - 850mb Wind Direction)

This index is based on an analysis of all Atlantic tropical cyclones from 1980 to 2000. Consideration of Pacific and Indian Ocean systems will be included if time permits.

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