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Two Caribbean disturbances to watch

By: Dr. Jeff Masters, 2:14 PM GMT on October 14, 2007

A persistent low pressure system extending from the Central American nations of Guatemala, El Salvador, and Belize northeastward over Jamaica, the Cayman Islands, Cuba, Haiti, and the Bahamas continues to dump heavy rain over much of the region. Heavy rains of at least five inches in northern Haiti triggered floods that killed at least 47 people Friday and left over 20,000 homeless. The flooding was worst in Cabaret, Haiti, near the north coast. No new rains fell Saturday, and further flooding is not expected. Heavy rain will continue to affect central and western Cuba today.

Connected to this deadly rain-making low pressure system is the large "sleeping giant" low pressure system that has been spinning over the Yucatan region the past week. This low continues to spin in the extreme southwest corner of the Western Caribbean, where Belize, Guatemala, and Honduras meet. Last night's QuikSCAT pass showed an elongated, poorly formed circulation, which will make development into a tropical depression today unlikely. None of the models develop the system. It is forecast to move northwest over the Yucatan Peninsula on Monday, emerging into the Gulf of Mexico on Tuesday. At that point, a trough of low pressure may be able to pull it towards a landfall near the Texas/Mexico border by Thursday. The trough may not be strong enough to turn the storm northwards, though, and it may come ashore in Mainland Mexico near Veracruz.

Even if the sleeping giant does not intensify into a tropical depression, this low could be a dangerous storm for Central America, bringing heavy rains of up to five inches to Belize, Guatemala, northwest Honduras, and Mexico's Yucatan over the the next three days. These heavy rains may also affect the Pacific coast regions of El Salvador, Mexico, and Guatemala, as the counter-clockwise flow of air around the low sucks in air from the Pacific Ocean.

Figure 1. Satellite estimated rainfall for the 24 hours ending at 2 am EDT Sunday.

New Caribbean disturbance
A tropical wave (98L) in the southern Caribbean is headed west towards Nicaragua and Honduras. This morning's QuikSCAT pass showed a fairly well-formed circulation. The system is under about 25 knots of wind shear, so any development today will be slow. Shear is expected to drop to 15 knots by Monday morning, which may allow for a better chance of development.

I'll have an update Monday.

Jeff Masters

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