Sea surface temperatures can be important variables regarding the likelihood for strengthening or weakening of a tropical system.  Conditions aloft are generally more important.  A tendency toward divergence aloft is likely to increase the strength of a hurricane and a tendency toward convergence aloft is likely to decrease the strength of a hurricane.  Gustav appears to be one of those typical noteworthy storms being influenced significantly by the warm temperature (and higher evaporation rates) at the surface.  The chart below shows heat potential for yesterday (Saturday, August 30).  I added the labeling and I drew the current location (which is nothing more than a guess on my part).

Hurricanes are very unstable.  Vertical motion is imperative to the maintenance of the system.  Though tap water in a sauce pan is stable when you first put in on the stove top, heating it from below tends to make it unstable.  The extreme case of boiling (by heating from below) provides us an example of violent instability.  Clouds are the markers in our otherwise transparent air (I’m ignoring visible pollution here) and the cumuliform varieties show us some of the vertical action occurring – akin to a slow motion rendition of the water boiling in the saucepan.

Conversely, cooling the air (or cooling the water in the saucepan) from below tends toward stability.  No one, wanting to get water up to a boil would put the saucepan on top of a block of ice.

Let us all hope that when Gustav moves over the relatively cooler water that is becomes “less unstable” and weakens significantly.  THE PROBLEM FOR ME IS THIS:  The color coding in such charts is misleading for some because the blues leave one with the impression that the water is cold.  It is not “cold.”  The second chart in this posting gives you a clearer impression of the actual temperatures yesterday.

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