HR: 0830h
AN: A41D-02    [Abstracts]
TI: On the Utility of a Modest Physics-Based High-Resolution WRF Ensemble for Hurricane Prediction: Hurricane Ivan as an Example
AU: * Tilley, J S
EM: tilley@rwic.und.edu
AF: Regional Weather Information Center, University of North Dakota P.O. Box 9007, Grand Forks, ND 58202-9007 United States
AU: Bower, K A
EM: katrina.naber@und.nodak.edu
AF: Regional Weather Information Center, University of North Dakota P.O. Box 9007, Grand Forks, ND 58202-9007 United States
AU: Kumar, S S
EM: sanatcumar@yahoo.com
AF: Regional Weather Information Center, University of North Dakota P.O. Box 9007, Grand Forks, ND 58202-9007 United States
AU: Kucera, P A
EM: pkucera@aero.und.edu
AF: Regional Weather Information Center, University of North Dakota P.O. Box 9007, Grand Forks, ND 58202-9007 United States
AU: Askelson, M A
EM: askelson@aero.und.edu
AF: Regional Weather Information Center, University of North Dakota P.O. Box 9007, Grand Forks, ND 58202-9007 United States
AB: The remarkable 2004 Atlantic hurricane season featured six "major" hurricanes (according to the Saffir-Simpson (SS) intensity scale), four of which directly impacted the state of Florida (Charley, Frances, Ivan, Jeanne) within a six-week period. Of these, Hurricane Ivan distinguished itself with impressive statistics in terms of lifespan (22 days), maximum intensity (SS category 5), damage (est. 13 billion dollars) and U.S. deaths (26). A variety of tools are currently available to forecasters at the National Oceanographic and Atmospheric Administration's (NOAA) Tropical Prediction Center (TPC), including several deterministic and statistical models as well as the Florida State University superensemble (e.g., Shin and Krishnamurti, 2003a,b). Often a blend of solutions from the various packages is utilized, though in other cases the TPC forecasters will follow the solution from a preferred model based on recent performance for the tropical cyclone of interest. Given that the NOAA National Centers for Environmental Prediction (NCEP) continue to move towards an operational environment where a relatively modest ensemble (roughly 6 members), constructed from within the Weather Research and Forecasting (WRF) framework, will figure prominently in the near future (DiMego 2004), a timely question to ask is whether the performance of such an ensemble for tropical systems will add value to the tool box now available to TPC forecasters. While a fully robust answer to this question demands a period of extensive testing under operational conditions, individual case studies can provide significant insights into some aspects of the expected performance of such a modeling system. Therefore, in this presentation we will present early results and limited performance metrics for such a case study, focusing on the 30-hour period beginning with Hurricane Ivan's entrance into the Gulf of Mexico. We note that while our 7-member ensemble consists entirely of WRF model members, in line with NCEP's planned approach, for this case study we limit the ensemble diversity to WRF physics schemes while utilizing higher resolution (2.5 km) for each member. As such, we hope to gain insight into the utility of such ensembles, at such resolution, for prediction of the meso-beta to meso-gamma structure and evolution of tropical cyclones, particularly strong systems such as Ivan.
DE: 3314 Convective processes
DE: 3337 Numerical modeling and data assimilation
DE: 3354 Precipitation (1854)
DE: 3374 Tropical meteorology
DE: 3394 Instruments and techniques
SC: Atmospheric Sciences [A]
MN: 2005 Joint Assembly