Extended Abstract (244K)8D.3
Investigating convective elements in a high resolution simulation of Hurricane Opal(1995)
Glen Romine, University of Illinois, Urbana, IL; and R. Wilhelmson
Landfalling hurricanes are frequently accompanied by localized severe weather, which may extend well outward from the cyclone center. The public generally recognizes the threat of severe weather near the center of the cyclone, but is less aware of the fact that severe weather can occur well away. In fact, the actual threat of localized severe weather is often maximized at a distance of 200-400 km from the eye in outer hurricane rainbands, where shear and buoyancy are favorable for the generation of tornado producing storms. Recent high-resolution simulations within the modeling community are now providing novel insight into the role of convective scale processes in hurricane organization and evolution. Using mesoscale models at cloud-scale horizontal resolutions, it is now possible to resolve individual convective elements within their parent cyclone environment. This study examines a high-resolution (1.1 km) simulation of Hurricane Opal (1995) carried out using the MM5 with an emphasis on probing the convective scale processes associated with outer rainband convection in addition to examining the larger scale circulation and organization. The simulated hurricane achieves an intensity and track that is very similar to what was observed. The asymmetry of Hurricane Opal is well captured in the simulation, as is the explosive deepening rate. Convective elements exhibiting analogous behavior to tropical cyclone mini-supercells are found to preferentially track along ascending branches of boundary layer vortices, which in turn appear enhanced by convectively induced vertical motions. Preliminary results from the high resolution simulations will be presented.
Supplementary URL: http://pampa.ncsa.uiuc.edu/~romine/opal.html
Session 8D, Tropical Cyclone Simulation: Dynamics II (Parallel with Sessions 8A, 8B, and 8D)
Wednesday, 1 May 2002, 8:30 AM-10:30 AM
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