Bill track 2009
Below are the wind center fixes and the track made from them
for Bill. The fixes were determined during post-processing using
methods developed by Dr. Hugh Willoughby and represent the center of
the tropical cyclone's wind field. Some fixes may be excluded, usually
due to closeness to or incompatibility with other fixes. On occasion,
interpolated points were included to make the track reasonable. The
reference altitude and source aircraft of the fix are also given, since
for weak or sheared systems the wind center may not be aligned vertically.
Following the fixes are the start and end times of inbound and outbound
legs of the aircraft, used to make horizontal profiles of the storm.
The centers are connected into a continuous track by using a series of
spline curves with varying degrees of curvature. The latitude and
longitude positions were output every two minutes to make the track
Please note that this track is NOT the same as the NHC Best Track.
That can be found here.
This track is to be used with wind and sonde data for flights into
this storm, but caution should be used when using this track with
other data, such as radar. The wind field track is not the most
conservative measure of storm position, and may include many small
wobbles due to trochoidal motion of the wind center.
Willoughby, H.E., and M. B. Chelmow, 1982, "Objective determination of
hurricane tracks from aircraft observations", Mon. Wea. Rev.,
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Last updated: April 8, 2010