Poster Session P2B.15 A Technique for Anticipating Initial Rapid Increases in Intensity in Tropical Cyclones, Using 37 gHz Microwave Imagery

Thursday, 1 May 2008
Palms ABCD (Wyndham Orlando Resort)
Margaret E. Kieper, Independent Consultant, Burnsville, MN

Handout (745.5 kB)

An alternative approach is proposed for aiding in forecasting significant rapid increases in intensity (>=25 kt / 24 hr) that commence when tropical cyclone intensity is initially in the 50-70 kt range: a focus on rainband structure in the core region of the tropical cyclone, preceding the development of deep convection, as observed in the higher-resolution 37 gHz microwave imagery. Specific features, visible as shallow convective rainbands, are shown to be present at the initiation of a period of rapid increase in intensity. During this period, successive microwave images reveal patterns identifying a continually-improving trend in structural organization. Conversely, tropical cyclones that lack these initial rainband patterns in the microwave imagery to begin with, or display the initial patterns, but fail to maintain a trend of improved organization, do not undergo rapid increases in intensity. Different trends are shown to each correlate with a specific range of intensity change. A forecast methodology is developed based on identification of these patterns in a comprehensive review of the 37 gHz microwave imagery of the 2003-2007 NATL hurricane seasons. This forecast methodology is evaluated, and correlated with the SHIPS RI Index for this set of named storms.
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