Figure 1

Figure 2

Figure 3

Figure 4

A plot of minimum central pressure vs. day/time shows the life cycle of Floyd (Figure 1). One interesting feature before rapid intensification took place was a pressure drop followed by a rise that took place between 03 UTC and 21 UTC on September 11 (Julian Day 254). The IR image from 03 UTC (Figure 2) shows the beginning of an eye and indicates a more intense system compared to the later time of 1615 UTC (Figure 3) which doesn't show the eye as well. The eye appears again by 21:15 UTC (Figure 4). 

Onset Loop

IR Loop

The hurricane began to intensify rapidly around 23 UTC on September 11. The following Onset Loop is centered around the onset time of rapid intensification.  Rapid intensification is defined as 42 mb/day by Holliday and Thompson (1979), except in the  Atlantic basin where Kaplan and DeMaria (1999) found it to be around 28 mb/day.  Hurricane  Floyd was approximately 38 mb/day, well within the criteria for rapid intensification in the  Atlantic basin.Note the deep convection (coldest cloud top temperatures) developing near the center of the circulation as well as warm cloud top temperatures in the center of the circulation indicative of the eye. At approximately the midpoint of rapid intensification (near 19 UTC) the IR loop shows a well developed eye with deep convection all the way around it. Note this loop has higher temporal resolution since an RSO (Rapid Scan Operations) had been called on GOES-8 during this period. The increased temporal resolution shows better continuity. 
 

IR Loop

Visible Imagery

During the time of maximum intensity (minimum central pressure between 921-923 mb) on September 23 the IR loop shows the classic features associated with a major hurricane, the warm well defined eye with a circular and symmetric cold ring and divergence at storm top. The visible imagery for later in the day shows these same features. Note the winds are cyclonic and directed away from the center of circulation at the inner core region, near the center, and at the cloud top outflow. Further away from the center of the hurricane the flow becomes more and more anticyclonic.