87th AMS Annual Meeting

Monday, 15 January 2007
2004 Hurricane Danielle Tropical Cyclogenesis Forecasting Study Using the NCAR Advanced Research WRF Model
212B (Henry B. Gonzalez Convention Center)
Nelsie A. Ramos, Howard University, Washington, DC; and G. S. Jenkins
Poster PDF (386.8 kB)
One outstanding forecast issue by forecasters is that the genesis of a tropical storm is not well predicted. The importance in the study of the genesis process lie in that most of the hurricanes in the Atlantic Ocean develop from cyclones that build up off the west coast of Africa. A study made by Thorncroft and Hodges (2000) shows that a notable positive correlation exist between the African easterly waves (AEW) activity and Atlantic tropical cyclone activity. The 2004 Atlantic hurricane season showed proof of this correlation with eleven of sixteen tropical systems being developed from AEWs. Because of their relevance further understanding of the nature of AEWs is desired, including their initiation, growth, and interaction with convective systems.

Hurricane Danielle is one of the 2004 hurricane season systems that developed from an AEW and the purpose of this study is to examine its genesis through the Weather Research and Forecasting (WRF) model. The ability of WRF model to anticipate the tropical cyclone formation is analyzed at 4.5 days and 2.5 days forecast periods prior to development into tropical depression (TD). Results of the two simulations forecast periods are compared and evaluated in terms of the WRF integration length, domain size, and cumulus parameterizations used. In addition to the model output data, NCEP re-analysis, Meteosat-7 IR satellite images, TRMM precipitation data, and resources from the National Hurricane Center archive are used to study the factors that governed the progress of the AEW that later intensify into Hurricane Danielle.

For simplicity, the cyclogenesis analysis is divided in four phases that are: EW while inland, EW coming off the African coast (EW2), TD and tropical storm (TS). Outcome obtained by the 2.5 days forecast period ahead of the TD stage shows the WRF model ability capturing the genesis process.

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