P1.28
The highly asymmetric structure of Hurricane Earl (1998) near landfall
Mark A. Croxford, Univ. of Hawaii, Honolulu, HI; and M. L. Black
Tropical cyclones (TC) sometimes interact with mid-latitude troughs resulting in a "hybrid" structure not typical of a classic TC. This may cause the storm to have an extremely asymmetric wind field and have a satellite signature which can lead to an underestimate of the storm's intensity. One such TC, Hurricane Earl, made landfall near Panama City, FL as a category one system at 0600 UTC 3 September 1998. Dvorak estimates of Earl's intensity peaked in the 25 m/s range yet the minimum surface level pressure reached 985 mb, supporting a much higher wind speed than the satellite-based estimate. Observations from a NOAA P-3 research flight and Air Force reconnaissance missions showed a highly asymmetric wind field with wind speeds greater than hurricane force confined to a large rainband ~150 km east of the center. Radar observations from the NOAA aircraft also indicated an asymmetric structure with convection limited to rainbands north and east of the eye. A quasi-eyewall was also observed but flight-level (~3 km) winds indicated that the wind center was actually within the high-reflectivity region of the northern eyewall. This is suggestive of a sheared and tilted vortex with possible baroclinic influences. A combination of data from USAF reconnaissance sorties and A NOAA research flight, including airborne radar and GPS dropwindsondes are used to investigate the thermodynamic and kinematic fields of Hurricane Earl near landfall. A discussion of the hybrid structure of this TC will be presented.
Poster Session 1, Lunch Poster Session (Lunch provided at Convention Center with sponsorship from Aerosonde Robotic Aircraft Pty Ltd, Hawthorn, Vic., Australia)
Wednesday, 24 May 2000, 12:00 PM-1:45 PM
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