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Tropical Cyclone Ana
Advisory 1
1:50 PM EDT
Saturday August 15, 2009
Ana remains a weak tropical cyclone
After advisories being reinitiated on Tropical Depression #2 at 12:30 AM EDT this morning, our first named storm of the season was declared at 5 AM EDT. Since then, convection has been waning around the system as Ana has encountered shear and dry air, with the shear being caused by a ULL to the north of Ana. These factors should inhibit strengthening of Ana for the next 24-36 hours. Ana should have better conditions to strengthen following that time frame.
As of the 11 AM EDT advisory issued by the National Hurricane Center, Ana is a weak tropical storm. I was about to call Ana a depression in my unofficial advisory, but a recent burst of convection on the eastern side of the storm, as well as its organization, have convinced me to keep it as a tropical storm. However, I believe it will be downgraded to a TD before the shear is done with it over the next 24 hours.
Because of the lack of convection over the center of Ana due to the shear and dry air, it is easier to tell its current position and movement. Currently, I believe the center of Ana to be around 14.4N and 48.6W. Overall, Ana is moving west at about 16 MPH, although it seems to have been moving just north of due west over the past couple of hours. Whether or not this is a temporary movement or a more permanent one remains to be seen.
Both the intensity and track forecasts are problematic, as they both are effected by the other, and they are also effected by how long the shear and dry air continues to affect Ana. The weaker Ana stays overall, the more south and west its track will be, and it would move through the northern Caribbean, and be affected by the mountainous terrains of Hispaniola and Cuba, which would keep it weak. If Ana recovers from the shear and dry air and strengthens quickly, it can take a more northern path, and affect the Bahamas and Florida. Currently, I believe Ana will follow the first scenario, and affect the northern Caribbean as a weak system. However, things can change very quickly, and I urge all the northern Caribbean islands, the Bahamas, and Florida to watch this system, as anything can happen in the tropics. The Lesser Antilles will be the first to be effected by Ana, and a tropical storm watch could be issued for the area later today.
The computer models are split across the northern Caribbean, and are disagreeing on where to take Ana. The 12Z CMC and GFS models both take Ana, or its remainments, across the Caribbean islands. The 12Z NOGAPS takes Ana through the Florida straits, over the Cuba. The 12Z BAM models are split all across the northern Caribbean. The 12Z GFDL is the southern outlier, taking Ana below Hispaniola and below most of Cuba. These computer models will continue to change over the coming days as the effects of the shear and dry air on Ana become clearer.
INITIAL 35 KT
12HR 30 KT
24HR 35 KT
36HR 40 KT
48HR 45 KT
72HR 45 KT
96HR 45 KT
120HR 45 KT
