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Norcross: The tropics are busy left, right and center in the Atlantic

Sept. 11 Atlantic Overview.
Sept. 11 Atlantic Overview. (National Hurricane Center)

There are two disturbances near Florida and two more on the other side of the Atlantic that could develop. Of that group, Disturbance #3 is the one of most interest to South Florida.

In between, Tropical Storms Paulette and Rene are both forecast to strengthen with Paulette reaching hurricane strength and threatening Bermuda.

Disturbance #1 is weak and disorganized, but has a slight chance of developing into a tropical depression when it reaches the western Gulf in a couple of days. There is no indication at this point it would get very strong.

Disturbance #2 is a large and impressive-looking area of disturbed weather moving across the Bahamas. It appears to be getting organized. The disturbance will move across the Florida peninsula later today and tomorrow bringing a strong surge of tropical moisture. Rainfall could be quite heavy in some areas.

Satellite image of Disturbance #1 and #2.
Satellite image of Disturbance #1 and #2. (CIRA/RAMMB)

It could become a tropical depression over or near the Florida peninsula or the Keys later today or tomorrow, as the upper-level winds slowly become more conducive for the system to organize. The system will have to be watched as it tracks toward the northern Gulf coast over the weekend into early next week.

In the central Atlantic, Tropical Storm Paulette is dealing with hostile upper-level winds, which are disrupting its circulation. A more supportive atmosphere is ahead, however, so Paulette is forecast to be a well-developed hurricane when it is in the vicinity of Bermuda early next week.

Some computer forecast models predict that Paulette will track west of Bermuda, and some to the east. That difference may affect the track of Disturbance #3 down the road.

Tropical Storm Rene is also part of the equation that could affect Disturbance #3. Rene is sputtering and moving slowly to the north. It’s going to run into blocking high pressure soon, however, and likely drift around for a while during the first part of the week. The computer forecast models indicate that dry air and hostile winds will take a toll and weaken Rene as it flounders in the middle of the ocean. But how much it will weaken and how fast is an open question.

That brings us to Disturbance #3, which in over the far eastern Atlantic. It’s a fairly large and elongated system, which makes it harder to forecast since we’re never sure where the circulation is going to consolidate.

Sept. 11 satellite image of the tropics.
Sept. 11 satellite image of the tropics. (CIRA/RAMMB)

It’s not clear if the broad system will split into two parts with one part speeding off to the west, or where it will consolidate. That’s important because the forward speed of the final circulation center is important to its final destination.

In addition, the strength of Rene and to some degree the location of Paulette may play a role in Disturbance #3′s track as well.

Rene and Paulette represent weak spots in the blocking high pressure system to the north. The stronger Rene is and the farther east Paulette is, the weaker the block. If Disturbance #3 moves quickly or stays fairly weak, it may skip by the opportunity to turn north. If it gets strong sooner, moves more slowly, and/or Rene stays fairly strong, the path north should be available.

This all boils down to an unforecastable set of moving parts. If the system stays on a southern track, it will end up in a location we don’t like with a lot of land areas ahead of it.

If it were to reach the islands, it would be there about Wednesday or Thursday of next week on the current schedule, so we’ll be watching this system for a good while. If it’s the next system to develop into a tropical storm, it will be named Sally.

Disturbance #4 is right on #3′s heels. In the slower #3 scenario, the two systems might interact causing additional forecast challenges. In any case, it appears reasonably likely to develop as well. The following name on the list would be Teddy.

We’re one day past the peak of the hurricane season – the day we are most likely to have a named storm active somewhere in the Atlantic, the Caribbean, or the Gulf of Mexico. But the National Weather Service in Miami did an interesting calculation. It turns out that a bit more than 60% of the South Florida landfalls have happened after this date. That’s because we’re more likely to have a hurricane in October in South Florida than in other parts of the Atlantic.

The bottom line is, we’re not on the downhill slope yet. We have to stay vigilant.


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