6:30 PM EDT Update 24 August 2012
Isaac is now an upper-end Tropical Storm with a well-defined center of circulation and solid banding features. In fact, within just the past few hours, there is a hint of a weak eye trying to form.

In the near term, the greatest forecast challenges for Isaac have to do with how much land interaction he is going to have, and how much of it is going to be mountainous. It is expected that the cyclone will quickly pass over western Haiti and eastern Cuba, with little serious deterioration to its core, allowing Isaac to then ride along the northern coast of Cuba, slowly restrengthening.

The above is made even a little more complicated by the fact that Isaac has been trending stronger, and heading a little more north than expected, likely in response to being much better organized this afternoon.

NHC's latest forecast is truly threading the needle, and it would not be surprising to see meaningful changes, up or down, east or west, to it, as the cyclone makes its way through this region, which basically means that everyone within and just outside the "Cone of Uncertainty" should be taking necessary precautions by this time.

Keep in mind that Isaac has tropical storm winds extending up to 185 miles from the center. This is a relatively large tropical cyclone, and a Tropical Storm Warning is now up for Andros Island, with Tropical Storm Watches up for the northwestern Bahamas, and all of the Florida Keys, the Florida east coast south of Jupiter Inlet, the Florida west coast south of Bonita Beach, Florida Bay and Lake Okeechobee. These are in addition to the watches and warnings immediately in Isaac's path.
Ciel

11 AM EDT Update 24 August 2012
Soon after the morning post, things started to turn around with Isaac, and it is now beginning to strengthen.

7:15AM EDT Update 24 August 2012
Today is 20 years to the day hurricane Andrew hit south Florida. For pure wind damage, no storm since has come close, only Katrina caused more damaged (mostly due to storm surge).

Isaac this morning has not improved much overnight, and the trend of a weak stop with some energy moving west and the center being pulled north appears to be going to continue to keep it weak at least most of today.

Because much of the energy is to the south of the reported center, Jamaica now has a Tropical Storm watch up.

Without a definitive center the actual path of Isaac will be difficult to determine, even today. Luckily, if it remains weak and disorganized, other than rain, the wind threat likely wouldn't be so great for the islands it is approaching.

On the other hand, based on recon data, the elongated axis, or "center", appears to be stair-stepping toward alignment, and as usual, if this manages to align and stack up vertically, there isn't much to prevent strengthening. It seems much more close to being stacked (or even may already be so, which would indicate a strengthening storm as it approaches the islands, which is not so good)

Bottom line, today is the day where Isaac could get its act together, and the future track hopefully will become more clear, but it hasn't done it so far this morning, although there are more signs that it may. Still, the dropsonde data indicates the surface center is north of where the flight level center is, thus the NHC's advisory position being on the north side.

11PM EDT Update 23 August 2012
There was a good good shift west with the 11PM advisory in the long term, and places it in the Central Gulf, but interestingly in the near term it shifted right (toward the keys).

There will likely be more adjustments to the track, thankfully intensity is kept low due to how weak Isaac is now, and the land interaction forecast, up until it gets into the Gulf, where it is forecast to reach hurricane strength.

Tomorrow will likely be a critical day in determining the future path of Isaac.

Those along Florida, the Gulf coast in particular, in the northern gulf, Alabama, Mississippi, and Louisiana, need to watch Isaac closely tomorrow and over the weekend. Based on the forecast, the Florida Keys are likely to have tropical storm watches issued sometime tomorrow.

There is very high uncertainty in the forecast beyond 3 days out.

"Split" systems are notoriously mind numbing to track, many times they fall apart, rarely do they come together, however the water temps are very much in favor of it bucking the odds tomorrow afternoon especially (then or probably never if it crosses Haiti)

11AM EDT Update 23 August 2012
TD#10 was upgraded to Tropical Storm Joyce, not affecting mainland land, but could approach Bermuda.

Isaac's track has not changed much, and the spread is still fairly much the same. All of Florida and the Gulf will need to watch. Isaac may be weak right now, but it is a very large system, and impacts will be felt a good distance from wherever the center passes. A large system is more capable of driving storm surge along the coast as well.

Strength wise, conditions are very good for intensification when, and if, it gets its act together.

7AM EDT Update 23 August 2012
Tropical Storm Isaac remains a large but disorganized Tropical Storm this morning, as recon failed to find an organized center overnight, and wind speed is down to 40mph. It seems to be still suffering from competing centers.

Today is a day of transition and not much will change with the future track, tomorrow becomes more interesting based on how close and how much time the system spends over Hispaniola. Conditions are expected to improve tomorrow, and Hurricane Warnings are up for Hispaniola, mainly in the southwestern part, and all of Haiti.

In the short term, jogs and center relocation will make getting a handle on the future track difficult, but the general pattern of the NHC's track seems good.

TD#10 will likely be upgraded to a Tropical Storm later today, and Bermuda is in the long range cone.

8PM EDT Update 22 August 2012
Tropical Storm Isaac is now in the Eastern Caribbean, and still moving westward around 21mph.

Isaac has remained relatively weak and disorganized today, as the center appears to not have solidified around a single vortex.

Tomorrow conditions may be more favorable for development.

Hurricane Warnings are now up for the Dominican Republic and Hurricane Watches are now up for Haiti. Eastern Cuba may see watches/warnings tomorrow.

The NOAA Gulfstream jet did not fly today, but will tomorrow, so model runs starting Friday should be a bit better. initialized.

Anywhere in the cone should keep track of what Isaac is doing. Hopefully by the time it nears Hispaniola a better trend (west, east, current) can be found for future movement.

Noaa Hurricane Research Division Flight twitter

9:15 AM EDT Update 22 August 2012
96L is likely to become TD#10 today, this storm will likely stay out to sea.

7:00 AM EDT Update 22 August 2012

Tropical Storm Issac is currently about 280 miles east of the Lesser Antilles this morning, and moving westward around 18 miles per hour. It will likely cross the northeastern Caribbean islands this afternoon, and be in the northeastern Caribbean, the forecast takes it to hurricane status by the time it is south of Puerto Rico. Because of the proximity to Puerto Rico at the time, and it being in the cone, Hurricane Watches are now up for Puerto Rico and the US Vrigin Islands. The closest approach to Puerto Rico should be around Tomorrow Afternoon.

Beyond that, it is forecast to approach the island of Hispaniola, still as a hurricane, so Hurricane watches have been raised for the Dominican Republic. Saturday morning is when it should be near Hispaniola.

The forecast then takes it briefly across the western part of Haiti, and eastern Cuba, approaching the Bahamas and potentially Florida after that. Central and South Florida is in the cone as of this morning, but so is Jamaica, and the Northern Bahamas. It remains prudent to watch beyond the Hurricane Watch areas, but much could change that far out. Still, based on the official Hurricane track, if Isaac were to approach South Florida, conditions would deteriorate late Sunday Afternoon and Evening and landfall would likely be Monday morning is when it would be near South Florida, if it were to approach there as a borderline cat 1/2 hurricane.

Intensity forecasts are usually off and the strength of the system could be weak or strong based on exactly how much land interaction occurs with Hispaniola. Many systems have been torn up by the mountains there, never to fully recover.

Last year, another I storm, Irene was also forecast toward Florida at this point (See the forecast history for Irene (2011)), this one is in a similar spot, but conditions around it are different from last year. This is brought up to show that the forecast can change, and to keep watching it over the next few days, by the time it nears Hispaniola there should be a better idea of the eventual track of the system. You should have already prepared for hurricane season much earlier this year.

In short, those in the watch area need to prepare for a possible hurricane (PR/VI and Hispaniola), and those in the Bahamas, Cuba, and Florida need to keep tabs on this system especially as it nears Hispaniola.

The models will shift west and east over time, even the Gulf of Mexico to Carolinas cannot be ruled out, anywhere in the cone should be watching the system very closely.

4:30 PM EDT Update 21 August 2012
Based on recon reports and the best track update, TD#9 is to be upgraded shortly to Tropical Storm Isaac.

Original Update

Invest 94L has acquired sufficient convective organization to be classified as a tropical depression, and advisories have begun on Tropical Depression Nine.

Because of the forward speed, Tropical Storm Warnings have been raised for the Lesser Antilles islands of Dominica, Guadeloupe, Desirade, Les Saintes, Marie Galante, St. Martin, St. Kitts, Nevis, Antigua, Montserrat, Anguilla, and Barbuda.

Tropical Storm Watches are up for Saba, St. Eustatius, Saba, St. Eustatus, along with the British and US Virgin Islands. Puerto Rico, Veques, and Culebra.

TD9 has a solid structure with which to build on, and is now efficiently fending off dry air entrainment. Consequently, further development is likely, and Nine will probably become Tropical Storm Isaac later this morning, or afternoon.

The forecast is for a hurricane to be in the eastern Caribbean on Thursday, and moving still fairly quickly to the west, potentially interacting with the Dominican republic or Haiti on Friday, and possible moving near Cuba Saturday into Sunday. Beyond that is lounge discussion, anywhere in the cone should watch the progress of this system very closely. This storm is in a similar position and setup to Irene from last year, so in reality, if it survives the northern Caribbean islands, those in the US from south Florida on up the coast may want to keep track of it. Puerto Rico and the US VI are in the Tropical Storm watch area.

Invests 95L & 96L continue slowly organizing. With 95L just south of Texas, and at least a 30% chance of becoming a tropical depression or storm within the next 48 hours, this is the most concerning of the two. 96L is following on the heels of Nine, but is several days away from becoming any potential threat to land masses.

Discussion on (now) TD 9 has been lively in the Forecast Lounge .

Flhurricane French Antilles Radar Recording of Isaac approach - Alternate View

Long Term RBTOP Satellite Float of Isaac (2012) -- Alternate style

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