An Extreme Event in the Eyewall of Hurricane Felix on 2 September 2007

During a routine penetration into Hurricane Felix late on 2 September 2007, NOAA42 encountered extreme turbulence and graupel, flight-level horizontal wind gusts of over 83ms(-1), and vertical wind speeds varying from 10 ms (1) downward to 31ms (1) upward and back to nearly 7ms (1) downward within 1 min. This led the plane to rise nearly 300m and then return to its original level within that time. Though a drop-windsonde was released during this event, the radars and data systems on board the aircraft were rendered inoperable, limiting the amount of data obtained. The feature observed during the flight is shown to be similar to that encountered during flights into Hurricanes Hugo (1989) and Patricia (2015), and by a dropwindsonde released into amisovortex in Hurricane Isabel (2003). This paper describes a unique dataset of a small-scale feature that appears to be prevalent in very intense tropical cyclones, providing new evidence for eye-eyewall mixing processes that may be related to intensity change.

http://dx.doi.org/10.1175/mwr-d-16-0364.1

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