Tropical Storm Hanna

Quick Gustav update: Recent recon found 973.4 mb at the center. That's another 2 mb down from the last pass, a drop of 18 mb since this morning when it came off of Jamaica.

Tropical Storm Hanna:

The storm is currently asymmetric, with most of the convection on the eastern side of the storm. A upper-level low has been present to the west of Hanna, creating strong shear on the western side of the system. A substantial burst of convection occurred in Hanna, causing the center of circulation to relocate in this location. However, the shear from the upper-level low has taken a toll even on this burst of convection and the center of circulation is now exposed. An additional burst of convection has occurred in the last hour or so, but it was not as intense as the last burst. The shear will have to reduce for additional development. The red circle indicates the exposed center.

And this upper-level low will weaken as it moves westward away from Hanna, leading to a more conducive environment for development soon. Hanna will be located over warm sea surface temperatures, decent tropical cyclone heat potential waters, in a region of low shear, and under an upper-level anti-cyclone. All of these variables should allow Hanna to develop over the next two days or so into a hurricane. Hanna's environment is not quite as good as Gustav's, so rapid development is less likely.

The ridge that has been currently holding Hanna to the south, keeping her moving westerly will weaken allowing Hanna to move more northwesterly over the next two days. The ridge will restrengthen by the end of day 2 or on day 3, pushing Hanna back southwestward. This is a very unusual path for a tropical cyclone in the tropical Atlantic, so to have so many models picking up on it, it makes it seem like it is likely. The storm will push towards the Bahamas during the next week, likely stalling in the Bahamas or near Cuba. This is when things get tricky. Many of the models pull the storm back north as a trough digs off the eastern coast, others push it through into the Caribbean, and others push it through the Florida Straights into the Gulf of Mexico. At this point it is too difficult to tell what Hanna will do. A strong storm should feel the trough pretty easily, and I am starting to think it will most likely move back to the north. I am thinking eastern Florida and the entire east coast could be at risk from this storm. I do not currently think the Katrina/Rita type track is likely.

The strength is actually a bit easier right now in my opinion. We should see a Cat 1 hurricane in two days pushing towards the Bahamas. It is possible a Cat 2 storm develops if the storm pushes far enough south towards Cuba. From this point, the storm should stall and then pull back northwards as a trough moves towards the system, increasing shear. The storm will likely decrease in strength slightly to a weaker hurricane or strong tropical storm. This will then move up the eastern seaboard. However, this is 5-7 days out, so the models could change substantially over this week.