Models Shifting East

Haiti has inflicted quite a toll on Gustav over the last 24 hours or so, and in fact, Gustav is now a tropical storm with winds of 60 mph. The center of Gustav is now back over the warm water, but it will have to separate itself from Haiti before significant strengthening can resume. This should begin tomorrow morning.

Over the course of the last few runs, all of the dynamical guidance has shifted its tracks of Gustrav to the right, including the far left European and UKMET. However, I'm still not jumping on board with the NHC and the majority of the global models that move Gustav east of 90 degree West. A strong ridge is building over Gustav and should move the storm off to the west and, at times, WNW over the next 2-3 days. The models begin to diverge significantly in this time frame with some turning Gustav to the northwest as the ridge breaks down, and others keep the ridge strong and continue moving Gustav to the WNW.

My thoughts haven't changed much from yesterday, and I still am favoring the scenario of the ridge remaining stronger as suggested by the European, UKMET, Canadian, and Japanese models. The ridge should begin to weaken slightly by Labor Day and will then turn Gustav more to the northwest. Texas is still my landfall idea and particularly the upper Texas Coast from Galveston to the Sabine River.

My thoughts on the intensity have changed a little, mostly with regard to the short-term period. It appears that Haiti may have disrupted the core somewhat, and I think this will limit rapid intensification for the next 24-36 hours. After this period, Gustav is expected to be in an environment conducive to strengthening. High ocenic heat content and a moist ambient environment will all contribute to Gustav modestly strengthening. However, it appears that the only factor that may limit a rapid intensification phase before Friday evening would be moderate wind shear (15-20 knots). After Friday evening, wind shear is forecast to weaken below 5 knots. Therefore, the stage should be set by Saturday for Gustav to undergo rapid intensification, and it's quite possible it could be a Category 4 hurricane as it moves into the southern Gulf of Mexico Saturday evening.

While the thermodynamic state of the ocean isn't quite as favorable in the central and western Gulf as it is the northwest Caribbean, it is still capable of supporting a Category 5 hurricane. With low wind shear, moist air, and a high oceanic heat content in the Gulf, I think that Gustav will attain Category 5 status as some point. Also, eye wall replacement cycles will dictate fluctuations in intensity when Gustav does get that strong. As Gustav approaches the U.S. mainland, an increase in wind shear could limit strengthening and probably weaken it some. Regardless, I still feel that Gustav will be a Category 4 hurricane at landfall.

I'll have another update tomorrow unless something significant changes.