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Caribbean disturbance struggling

By: Dr. Jeff Masters, 1:02 PM GMT on September 28, 2005

The tropical disturbance in the central Caribbean sea, south of Jamaica, is struggling this morning. The amount of deep convection has decreased considerably since yesterday afternoon, and appears in small irregular patches around the weak circulation center. A reconnaissance airplane was scheduled to visit the area today but was cancelled. However, the convection has made a bit of a comeback since 2am EDT when there was almost none. The environment for development still seems fair to good. Wind shear over the disturbance remains in the 5 - 10 knot range, which is in the slightly to moderately favorable range for tropical storm development. This wind shear is forecast to decrease the next two days, and I still expect we will see this system become Tropical Depression 19 by Friday.

The disturbance has speeded up its forward motion to about 13 mph to the west-northwest. This motion is forecast to slow down over the next few days, which will keep the system in the western Caribbean through Friday night. The BAMM and GFS models both forecast that the system will then cross the Yucatan Peninsula and enter the southwest Gulf of Mexico. This seems reasonable, given the strong ridge of high pressure developing over the Gulf of Mexico.


Figure 1. Early run of the BAMM model takes the Caribbean disturbance into the Yucatan Peninsula. The GFDL model didn't do too well--it takes the disturbance the wrong way!

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. There are currently no suspect areas to focus on, though.

Hawaii and Baja
Hawaii is watching Tropical Storm Kenneth, which is expected to pass though the Islands Friday and Saturday. Kenneth should only be a tropical depression by then, but may bring heavy rains and the threat of flash flooding to the islands. Tropical depressions that have passed though the islands in previous years have caused serious flooding problems.

The Baja Peninsula is watching newly-formed Tropical Depression 15E, which may threaten the Baja Peninsula as a tropical storm by Sunday.

Jeff Masters

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.