Daily Archives: Sunday, August 21st, 2011

Tropical Storm Irene Forms….likely FL/US threat

Busy evening in the weather today.  I’ve been watching a number of tropical waves and disturbances over the last week or so.  Two of these formed, one was Harvey, and the other is Irene.  Harvey was a 65 mph tropical storm that has moved inland over Belize and will be dissipated overnight or early tomorrow.  The bigger story today is that Tropical Storm Irene has formed.

Hurricane Hunters went through the invest at the time and found winds of 50 mph and loosely closed cyclonic center.  This was enough to warrant the upgrade straight to a moderate tropical storm.  Below is the 11pm NHC information including warnings and watches:

  • Maximum sustained wind speed: 50 mph
  • Movement: W at 22 mph
  • Location: 15.3N 59.9W or 95 mi E of Dominica
  • Minimum pressure: 1006 mb
  • Tropical Storm Warnings: Puerto Rico, USVI, St. Maarten, Dominica, Barbuda, St. Kitts, Antigua, Anguilla, Nevis, Montserrat, and the BVI
  • Tropical Storm Watches: Southern coast of the Dominican Republic
Tropical storm warnings mean that tropical storm conditions with winds between 40 and 74 mph are occurring or will occur within 36 hours. Tropical storm watches mean that tropical storm conditions could occur within 48 hours.
My overnight concern is that of the eastern islands of the Caribbean where tropical storm force winds will be occurring in just a few hours.  Rain bands have already been pushing through this area and will continue for the next 24 hours or so.  Tropical Storm Irene is a very large system in nature, and it will take time to pass particular locations.  This will allow for large amounts of rainfall especially on the most mountainous islands.
Irene has a pretty good chance of intensifying faster than the normal tropical system because of nearly ideal conditions.  Throughout the life of Irene conditions will be generally very favorable for intensification. The only obstacles in the way are Hispaniola, Cuba, and …. Florida.  The 10,000 to 15,000 ft mountains of Hispaniola are generally the biggest obstacle of any tropical cyclone in the world in terms of islands, but in this case Irene may be just far enough south to miss most of these islands.
Irene’s forecast is a very difficult forecast with many puzzle pieces that will make up the outcome of Irene. During the next few days Irene will be driven west-northwestward by the strong Bermuda high pressure.  There is a weak upper level trough that may enter the picture as Irene gets close to Hispaniola, which may allow for a short term turn to the northwest and a gain in latitude as the trough passes by and until the Bermuda high builds back in. As the high builds back in, depending on both the strength of the high and that of Irene, Irene will turn back toward the west or west-northwest.
After that time, the models are in very good agreement that Irene will pass over either central or western Cuba where it will be caught by a stronger trough of low pressure which will cause a northern turn in the Florida straights or the Gulf of Mexico.  Where this crucial turn occurs will dictate what effects the state of Florida will get.
My best guess:  Irene stays south of Hispaniola entirely and enters the passage between Cuba and Jamaica before turning back towards the west.  From here Irene will cross Cuba as a hurricane and enter the southeastern Gulf.  Given the current models, I am thinking that Irene will likely make landfall anywhere from south Florida to the Alabama coastline. I will continue to watch this situation as I can.  Below is the current NHC forecast:
Personal Note:  Over the next few days I will be finishing my shadow at Bay News 9, taking the GRE, visiting with my sisters who are coming in from Afghanistan and New York, and moving to Tallahassee. I will be extremely busy during this time so blog posts will continue to be hit and miss.  I will be making updates at twitter at http://www.twitter.com/JonathanBelles as I can.  I will make more frequent updates after my move on Wednesday.


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