Extended Abstract (372K)5.1A
The along-shore variability of tropical cyclone landfalls
Douglas A. Stewart, Environmental Dynamics Research, Inc., Lantana, FL
The number of Atlantic tropical storms and hurricanes making landfall on the U.S. coast or passing within 100 nm of the coast averaged nearly seven per year over the past 152 years. The frequency of hits and near misses varies over decadal time scales and spatially along the coast. Quantifying the risk associated with U.S. tropical cyclone impacts currently relies on climatological storm statistics derived from some 1000 storms along a 3000 nm coastline. Since the number of storms influencing any particular coastal location is quite small, storm statistics for such a location are derived from storms affecting coastal regions as far as 250 nm away. It is not clear whether this data pooling masks any real along-shore variability of storm landfalls and close approaches, or to what extent the variability seen in the statistics is an artifact of the limited sample size.
In this study, storm track and intensity data from the HURDAT data base are combined with NCAR/NCEP reanalysis data to investigate the use of daily resolved steering flow and vertical shear estimates to help explain the temporal and spatial variability of land-falling tropical cyclones along the coast. The frequency of occurrences of onshore steering flow and vertical shear intensity along the coast are examined to address this concern. Results suggest that a combination of steering flow and vertical wind shear climatology explain much of the along-shore variability of land-falling storms. Statistics of the steering and shear flow are used to synthesize a large sample of storm landfalls to compare with the historical record.
Session 5, Regional Climate Models and Observations (Parallel with Session J8) (Room 609/610)
Wednesday, 14 January 2004, 1:30 PM-2:30 PM, Room 609/610
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