Rita has actually been passing through the cooler parts of the Gulf so far, north of Cuba. The water gets warmer and the wind shear is minuscule. I don't get the forecast for weakening. Yes, the waters get shallower, but they get warmer! It's not the shallowness that ultimately matters. It's the total heat that the hurricane has to work with.
Bingo....
I don't think the weakening issue has much to do with water temps, it has to do with wind patterns. It is all way above me head. In any event, there is uncertainty there too. Right now the storm is over a warm spot on your map. It is about to go over that blue spot on your map. I have no idea if that will matter.
Someone tried to hand this off to me today, too! Strange conjecture going on out there.