All the main global models have come on board forecasting the development of the 17th storm of the 2010 hurricane season in the southwest Caribbean next week. The southwest Caribbean is the place where late-season development typically occurs, so this is something to be expected, particularly during a strong La Nina season. Our best 2010 analog season, 1998, featured Category 5 Hurricane Mitch developing in the southwest Caribbean on the 22nd of October. Mitch killed over 20,000 people in Central America and southern Mexico. And in 2005, another analog for 2010, Hurricane Wilma, the strongest hurricane in Atlantic Basin history, formed in the southwest Caribbean on October 15th.
With such model support for development, I think we may well see a storm develop to the east of Nicaragua around next Tuesday, October 19th. Question is, where will it go? I can tell you where it isn’t likely to go - the northwest or north-central Gulf of Mexico. Persistent and rather strong mid and upper-level westerly wind flow across the central to northern Gulf of Mexico would steer any tropical cyclone moving out of the northwest Caribbean Sea almost immediately to the northeast toward south Florida or the Bahamas. And that may well be the fate of this potential storm.
Long-range models predict a rather deep trof and associated cold front across the eastern U.S. toward the end of next week. Such a feature would mean that steering currents could pick up anything developing in the western Caribbean and carry it northwest toward central to western Cuba by next Friday or Saturday. With the trof/front in place across the southeastern U.S., the storm could track to the north-northeast or northeast, possibly threatening southern Florida and/or the Bahamas before racing northward and out to sea. I think that this might be the most likely track of the storm should it develop. But there is another possibility - it could be blocked by high pressure building in behind the cold front to the north and shoved westward into Central America and/or southern Mexico, as was Hurricane Mitch in 1998.
As for its potential intensity, conditions aloft look quite favorable for strengthening next week. And with oceanic heat content quite high across the western and northwest Caribbean, any storm developing in the region next week could easily become a major Category 3 or 4 hurricane. I’d say possibly a Category 5, but I’m a bit wary of the fact that conditions across the region have been a little unfriendly toward development for some reason that we don’t understand this season.
Residents of the western Caribbean islands, South Florida and the Bahamas should pay close attention to the tropics over the coming days, as your season is not likely over just yet.