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StormTrack has moved: http://thestormtrack.com/

May 19, 2005

A note about tropical system strength

I just wanted to warn everyone not to pay too much attention to the wind speeds as a measure of the strength of a storm. Especially in hurricanes, wind speeds can be deceptive. Eye wall replacement cycles can cause winds to fluctuate without seeing any real change in the strength of a storm. Eyewalls can undergo replacement cycles multiple times a day. When an eyewall replaces, you will see an initial shrinking of the eye. With this shrinking of the eye, wind speeds will increase due to the conservation of angular momentum (much like a figure skater pulling in her arms). After this the eye will greatly expand and winds will drop accordingly. However, the central pressure should not change as significantly. The real judge of the strength of a hurricane is the central pressure. As the minimum central pressure drops (the system deepens), you will see a increase in the intensity of the storm. It is worth while to note that in the last 24 hours the central pressure of Hurricane Adrian has dropped about 20 mb.

For comparison, normal pressure at sea level is 1013.25mb, Hurricane Andrew was 922mb when he made landfall in Miami, and the lowest recorded pressure was in Typhoon "Tip" in Japan. The pressure dropped to 870 mb.
Tracking God's Fury:
Tropical Storm Maria
Tropical Storm Nate
Hurricane Ophelia
  • None
  • --
    Ask Bryan:
    What steers hurricanes?
    What is eyewall replacement?
    Jordan Golson
    Bryan Woods