The maximum intensity for each storm (where the potential vorticity was greatest) has been used to align all the storms before averaging was done to produce the composite data in this database. The offset then refers to the number of hours before or after the maximum intensity. Hence an offset of -12 hours is the average of all storms 12 hours before they reached their maximum intensity.

To select an offset, please either click on the figure below or on the buttons on the left.

Offset components
-60 -48 -36 -24 -12 0 12 24 36 48 60
-60hr -48hr -36hr -24hr -12hr 0hr 12hr 24hr 36hr 48hr 60hr