For the past few weeks, I’ve been discussing an upcoming pattern shift that would lead to tropical cyclone development in the Caribbean Sea between the 20th and 30th of September vs. the far eastern Atlantic (Danielle, Earl, Fiona, Gaston, Igor, Julia and Lisa). Long-range models were quite supportive of this idea from early in September. As of today, it looks like those long-range models are going to be right.
We’ve been following a tropical wave across the Atlantic for the past week. This wave, which we have identified as Tropical Disturbance 51, is now located in the eastern Caribbean Sea. On a side note, this wave appears to be the same one which spawned Hurricane Igor last week. Sometimes tropical waves can spawn several storms. Tropical Disturbance 51 appears to be getting better organized by the hour. A reconnaissance plane is scheduled to investigate it on Wednesday. I’m not sure if it will be strong enough to get upgraded to a tropical depression by then, but I think it may well be a depression or even a tropical storm by Thursday afternoon.
Although there was considerable disagreement among the various global models (U.S, Canadian and European) over the weekend as far as the potential track of the system, these models are coming into better agreement today. Such model agreement gives a forecaster more confidence in his or her forecast, but model agreement does not mean that the models are correct. In this case, the models indicate a general west to west-northwest track, taking the center near eastern Honduras on Saturday then northwestward toward the eastern Yucatan Peninsula on Sunday. That’s where the major uncertainty begins.
All of today’s runs bring the center near the eastern Yucatan Peninsula north of Belize on Sunday then move it very slowly northward for the next 2-3 days. By Wednesday, a cold front moving southward across the northern Gulf could pick up the storm and take it northeastward, possibly toward the Florida Peninsula, though the American model takes it across Cuba and south of the Florida Peninsula.
Where will it really go? That’s something I’m not at all sure of - yet. Any time steering currents get so weak such that a storm stalls makes for a very difficult forecast. The forecast track and setup sort of reminds me of Wilma in 2005. Wilma formed in the south-central Caribbean and tracked toward the northeast Yucatan Peninsula where it stalled for several days before being picked up by an approaching front and accelerating off to the northeast across south Florida. But the forecast also reminds me of another quite major hurricane from 1998 - Hurricane Mitch.
Initially, Mitch was forecast to get picked up by an approaching front and track northward into the Gulf. However, the front turned out being too weak and Mitch tracked westward into Nicaragua where it killed 10,000-20,000 people due to torrential rains. For now, my vote would be for the Wilma scenario, with a possible threat to Florida toward the middle to end of next week. That’s a long way out, though, to have much confidence.
One thing that does appear to be likely is that any storm moving into the northwest Caribbean will encounter extremely high oceanic heat content. The northwestern Caribbean Sea is dominated by a pocket of very warm water that is also quite deep. There is plenty enough energy there to support a Category 5 hurricane, not that any of the models is currently forecasting such intensity. But if the storm develops and stays over water, I think that there is certainly the potential that it could become a large and quite powerful Category 4-5 hurricane in the northwest Caribbean this weekend or early next week.
Beyond next week, I’m seeing signals which indicate additional development across the Caribbean Sea as we move into October. I don’t think that the 2010 hurricane season is going to be winding down until late October or November.