WRF Simulation of the genesis of Hurricane Javier (2004) in the Eastern Pacific

NASA is preparing for the Tropical Cloud Systems and Processes (TCSP) field experiment in July 2005, a joint effort with NOAA to study tropical cloud systems and tropical cyclone genesis in the Eastern Pacific. A major thrust of the TCSP program is the improvement of the understanding and prediction of tropical cyclone genesis, intensity, motion, rainfall potential, and landfall impacts using remote sensing and in-situ data, as well as numerical modeling, particularly as they relate to the three phases of water. The Eastern Pacific has the highest frequency of genesis events per unit area of any region worldwide. African easterly waves, mesoscale convective systems (MCSs), and orographic effects are thought to play roles in the genesis of tropical cyclones there. The general consensus is that tropical depressions form in association with one or more mid-level, mesoscale cyclonic vortices that are generated within the stratiform region of the MCS precursors. To create the warm core tropical depression vortex, however, the midlevel cyclonic circulation must somehow extend down to the surface and the tangential winds must attain sufficient strength (~10 m s-1) to enable the wind-induced surface heat exchange (WISHE) to increase the potential energy of the boundary layer air. To investigate the roles of the different possible mechanisms involved in the genesis of tropical cyclones in the Eastern Pacific, we use the WRF model to simulate the genesis of Hurricane Javier (2004).

The WRF model reproduces with reasonable accuracy the events leading to the genesis of Javier. Several different components appear to be involved: 1) convection along the ITCZ, 2) an MCS north of the ITCZ and a subsequent squall line, and 3) gap flow across the Isthmus of Tehuantepec. Many of these features are confirmed through GOES and Quikscat satellite data. The presentation will provide a more in-depth examination of these components and their roles in the genesis of Javier.