Hurricane Dean and Supertyphoon Sepat

There's a weak and disorganized tropical storm named Erin in the Gulf of Mexico and about to hit Texas -- but that's probably going to be more a rain than a wind event. I think most eyes are now focused on our first hurricane of the season -- Dean -- which was just upgraded this morning.

The forecasters are already being blunt about Dean's potential to be a very bad storm, perhaps even something along the lines of Hurricane Ivan. From a recent forecast discussion:

BASED ON WHAT WE THINK WE KNOW ABOUT INTENSITY CHANGE ... THERE DO NOT SEEM TO BE TOO MANY INHIBITING FACTORS TO A FUTURE INTENSIFICATION OF DEAN. GLOBAL MODELS UNANIMOUSLY DEVELOP A LARGE UPPER-LEVEL ANTICYCLONE NEAR THE CENTER OF THE HURRICANE AS THE SYSTEM TRAVELS INTO THE CARIBBEAN SEA. IN COMBINATION WITH VERY DEEP WARM WATERS ... THIS PATTERN WOULD FAVOR THE DEVELOPMENT OF A POWERFUL HURRICANE.

Here's the latest track for Dean, now showing a hurricane warning for the Lesser Antilles.

We simply have to assume that Dean is going to strengthen once it gets into the Caribbean. The storm might even intensify rapidly given the heat content of the ocean in this area. An important question thus becomes land interaction: One thing that will keep this storm weaker is if its particular track has it hitting lots of islands. If Dean remains very well organized and gets into the Gulf of Mexico, where there is also high ocean heat content, things could get scary indeed. Already, we have to expect that at least some pain will be felt in the Caribbean because of Dean.

The next National Hurricane Center advisories on Dean will come out at 11 am ET and 5 pm ET. I know that I, for one, will be checking in right on time. Already, I think it's fair to say that this storm is going to provide us with much more drama than the entire 2006 Atlantic hurricane season.

And if the Atlantic just got its first hurricane, the Pacific just got its strongest storm yet this year, Category 5 Supertyphoon Sepat, which is currently off the eastern coast of the Philippines and headed towards Taiwan and China. Sepat has maximum sustained winds upwards of 160 miles per hour and some estimates suggest the pressure has dropped below 900 millibars in the center of the storm. Indeed, the automated Advanced Dvorak Technique shows Sepat intensifying still further at the moment, and has the storm considerably stronger than the official forecast from the Navy's Joint Typhoon Warning Center.

Check out this scary image of Sepat, showing a tight cloudless eye that almost looks like a perfect puncture wound.

Yesterday at my blog The Intersection, I used Sepat to illustrate hurricane maximum potential intensity (or MPI) theory. In essence, MPI theory provides an equation capable of calculating a speed limit for any given hurricane in a particular region or climate. As I noted, Sepat is currently in a part of the world where many very intense hurricanes form and where the "potential intensity" is often extremely high. In fact, according to potential intensity calculations, Sepat has not yet achieved its theoretical peak (though it's not too far off, either).

Very few hurricanes achieve their maximum potential intensity, but some do. For this reason, maximum potential intensity theory is a leading reason for believing that global warming should cause the average hurricane to strengthen. Climate change is expected to increase the maximum potential intensity, period. And if it does so, then those storms that achieve their maximum potential will be achieving a higher one than before. By these lights, as global warming sets in we ought to see hurricane intensity records breaking across the globe -- and in fact, we have. Most recently, June's Cyclone Gonu was the strongest hurricane ever recorded in the Arabian Sea.

For more on hurricanes, global warming, and maximum potential intensity theory, see the work of MIT's Kerry Emanuel. It's a fascinating idea to explore -- between now and the next advisory on Hurricane Dean.