Caribbean disturbance still unimpressive

The tropical disturbance in the central Caribbean sea, south of Jamiaca, is still small and disorganized, and will not become a tropical depression today. The reconnaissance airplane scheduled to visit the area today will probably be cancelled. The disturbance has no surface circulation, surface pressures are not falling significantly, and there is about 10 knots of shear over it--which is marginal for tropical storm development. However, the largest burst of deep convection we've seen yet with this system began at about 4am EDT this morning, and the disturbance now has an expanding area of thunderstorms with cold tops that may signify the beginnings of an attempt to organize into a tropical depression. The disturbance has slowed its forward motion to about 10 mph to the west-northwest. This motion is forecast to slow down even further over the next three days, which will keep the system in the western Caribbean through Friday, and favor development.

I expect that we won't see a depression until late Wednesday, when the upper-level wind shear is forecast to relax significantly. I still give this disturbance a 70% chance of becoming a tropical storm by Friday, when it should be in the western Caribbean near Cuba or the Yucatan Peninsula. The global computer models do not develop this system into a tropical storm, and are not much help in forecasting what will happen. The GFS model predicts that the system will cross the Yucatan Peninsula into the southwest Gulf of Mexico early next week, but this forecast is too far in the future to give much credence to.


Figure 1. Early run of the BAMM model takes the Caribbean disturbance into the Yucatan Peninsula. It appears that the BAMM model got initialized with the disturbance too far to the south, so the projected track shown here is probably too far to the south.

Africa westward
The ITCZ is active in the region extending from the African coast westwards for 1000 miles. Some of the global computer models are forecasting that a tropical storm will develop along this area later this week.

Gulf of Mexico
A cluster of thunderstorms accosiated with the tail end of the cold front that pulled Rita northeast across the U.S. is over the northern Gulf of Mexico. Strong upper levels winds are producing 30 knots of shear over this region and should prevent any development for at least the next two days.

Alaska and Hawaii
We don't talk much about these states in my tropical blog, but Nome, Alaska had a huge mid-latitude cyclone hit them Friday. The storm brought sustained tropical storm force winds gusting to 52 mph, a 10-foot storm surge, and a pressure of 972 mb! This was in essence a Category 1 hurricane, as far as the storm surge and pressure go. Thanks to wunderphotographer Destiny, who brought this newspaper article to my attention.

Hawaii has its second tropical system of the season to be concerned with. Hawaii dodged major Hurricane Jova last week, andTropical Storm Kenneth is expected to pass within 100 miles of the Islands by the end of the week. Kenneth should only be a tropical depression by then, and bring a few extra rain showers to the islands.

Jeff Masters