Tropical Storm Gamma next week?

The tropics remain quiet today. Strong westerly winds blowing across the Caribbean are creating up to 80 knots of shear, making tropical storm development very unlikely for the next two or three days. However, all of the models are forecasting that these strong winds will relax and shear values will drop dramatically across the central Caribbean by Tuesday. The persistent area of low pressure and storminess that has affected the ocean areas between Panama and Nicaragua the past three weeks will expand. The GFS, NOGAPS, and UKMET models all indicate that a tropical storm may form in the south central Caribbean by the middle of next week.


Figure 1. GFS model forecast seven days from now, showing a tropical storm with copious rainfall (bright green colors) forming in the south-central Caribbean Sea.

It is highly uncertain what land areas might be at risk if such a development does occur. The three main possibilities would be:

1) A track like Hurricane Beta into Nicaragua.

2) A track like Hurricane Michelle in 2001, which struck southern Cuba then passed northeastwards through the Bahamas.

3) A track like "Wrong-Way Lenny" of 1999, the only hurricane ever recorded that took an extended west-to-east path through the Caribbean.

Anything that works its way far enough north is going to get picked up and quickly recurved northeastward by one of the many troughs of low pressure migrating across North America. This means that except for a low threat to South Florida, the U.S. would not be at risk. Additionally, given that there has only ever been one storm knicknamed "Wrong-Way", the eastern Caribbean would probably not be at risk, either. I'll be able to spend my vacation in Puerto Rico next week at the beach, instead of taking shelter at the Internet Cafe and writing blog entries. The primary area at risk would be Nicaragua, Honduras, Cuba, Hispanolia, Jamaica, and the Cayman Islands.

I'll be back with an update tomorrow morning. Remember that the computer models are rather poor at forecasting tropical storm development, and nothing at all may develop next week. But given that this is the Hurricane Season of 2005, I'd give at least 50/50 odds we'll see a Tropical Storm Gamma by late next week in the central Caribbean.

Jeff Masters