Stages of Development
from disturbance to hurricane
As surface pressures continue to drop, a tropical storm becomes a hurricane when sustained wind speeds exceed 64 knots. A pronounced rotation develops around the central core as spiral rain bands rotate around the eye of the storm. The heaviest precipitation and strongest winds are associated with the eye wall.

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Credits and Acknowledgments for WW2010.
Department of Atmospheric Sciences (DAS) at
the University of Illinois at Urbana-Champaign.