TD 9 has formed and will threaten the Caribbean, US

Invest 94L fired enough deep convection during the overnight hours to be considered a tropical depression, therefore, the National Hurricane Center has upgraded Invest 94L to Tropical Depression #9. TD 9 seems to be tracking a little south of due west at a forward speed of 18 to 19 mph. This system is currently located to the south of a west-southwest to east-northeast oriented high pressure system and this should keep TD 9 on a general westward track for the rest of this week. This track will bring TD 9 directly over the island of Dominica on Wednesday afternoon as a 50 to 60 mph tropical storm.

Once in the Caribbean, the track of TD 9/Isaac will be influenced by that high pressure ridge. Most of the forecast guidance show a track across the northern Caribbean, however, I think this may be too far of a north track, especially considering the depression’s current slightly south of due west track. Even the latest GFS model, which takes this system across central Cuba and then rakes all of Florida’s east coast before landfalling in eastern Georgia, seems a little too far north.

So, I’m leaning closer to the European model guidance track which takes TD 9/Isaac right across the islands of Guadeloupe and Dominica late Wednesday and then just south of Puerto Rico on Thursday. From there, the European model guidance forecasts that this system will miss Hispaniola and then track very close to the north coast of Jamaica on Sunday.

Beyond Sunday, the European model guidance forecasts a track that takes Isaac-to-be across western Cuba next Tuesday and then northward towards western Florida and the Florida Panhandle by next Thursday as possibly a hurricane.

So, all residents and vacationers in the Leeward Islands, Virgin Islands and Puerto Rico should prepare for tropical storm conditions. Those of you further west across Jamaica, the Cayman Islands and Cuba should closely monitor the progress of TD 9/Isaac. It is looking more and more likely that this system will be a hurricane when it tracks very close to Jamaica on Sunday.

Finally, all residents and vacationers across the Florida Peninsula and the Florida Panhandle need to keep very close tabs on the forecast track of this system. Go over your hurricane preparedness kits today and make sure you know what to do should Isaac come knocking on Florida’s door later next week.

~ Rob Lightbrown, Crown Weather Services