VITAMINS FOR GUSTAV

Tropical Storm Gustav weakend after moving over the southern tip of Haiti Tuesday as a hurricane . Although its winds have dropped to 60 mph it is expected to strengthen once it gets into the Gulf of Mexico.

Intensity forecasts are tricky to predict; much harder than track forecasts, but looking at the sea surface temperature along the forecast path can give clues as to how much the cyclone may strengthen. The SST typically needs to be at least 79 to 80 degrees or warmer for a strengthening tropical cyclone. But more importantly is the depth of the warm water below the surface. Deep warm subsurface water makes it difficult for colder water to upwell or rise to the surface. A cyclone evaporates warm water and extracts the heat to power the intense winds. The graphic above shows the Potential Heat Potential of the Atlantic Basin. This summarizes the depth of warm water and how it could impact the potential fueling of a cyclone. Its like a storm taking vitamins when it moves over an area of red or orange. I have overlayed the NHC track over the current Potential heat map. See how the NHC is strengthening Gustav to a category 3 hurricane once it passes over the red areas. You can see daily updates to this map at http://www.aoml.noaa.gov/phod/cyclone/data/at.html

A storm should intensify when the OHC exceeds 60 joules per kilogram. You can see the legend and pinpoint areas above 60 Kj/cm. Ivan was an example of a hurricane that intensified as it passed south of Cuba. It set a record as a cat 4 for 8 days.