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Matthew dissipates; new Western Caribbean disturbance organizing

By: Dr. Jeff Masters, 5:28 PM GMT on September 26, 2010

Tropical Storm Matthew has dissipated over the high mountains of Mexico, in the same region where Hurricane Karl came ashore. Matthew's remains will dump very heavy rains over a region that doesn't need it, and flash flooding and mudslide will be a concern over this region of Mexico for the next two days. Guatemala was fortunate--Matthew did dump some heavy rain of up to six inches over the country, but the storm unexpectedly moved well beyond the country, and heavy rains have avoided both Guatemala and Belize today. Venezuela was not so lucky, and heavy rains from Matthew are being blamed for the deaths of seven people in Caracas.


Figure 1. Afternoon satellite image of the Western Caribbean and Central America, showing the remains of Matthew over Mexico, and a large area of disturbed weather beginning to develop over the entire region.

Lisa
Tropical Depression Lisa is being torn apart by wind shear, and will likely not exist by Monday morning.

A wet week for the Western Caribbean
A large region of disturbed weather is developing over the Western Caribbean and Central America today. These sorts of large low pressure systems are very dangerous for Central America and the Western Caribbean, even if they do not spawn a tropical storm. In October 2007, a large low I dubbed "the sleeping giant" spent a week spinning over the region, dumping very heavy rains over all of Central America and the countries bordering the Western Caribbean. Rains from this system triggered flooding that killed 45 people in Haiti, damaged thousands of homes in Cuba, and caused heavy rains in Guatemala, El Salvador, Belize, Mexico, Jamaica, the Cayman Islands, and the Bahamas. The models predict a similar type of storm may evolve over the region over the next few days, and heavy thunderstorms from this disturbance are already affecting the Pacific coasts of Nicaragua, El Salvador, Coast Rica, and Honduras. Heavy rains will likely spread to Jamaica, Cuba, Southwest Haiti, and the Cayman Islands on Monday. These rains may be as great as 3 - 6 inches per day, and will be capable of causing dangerous flooding and mudslides. The models continue to have a poor consensus on the future evolution of this area of disturbed weather. The ECMWF model predicts that by late in the week, the low will get drawn north-northeastwards over Cuba and into South Florida and the Bahamas, and may not develop into a tropical storm. At the other extreme is the GFS model, which predicts that the low will spawn a series of two or three tropical storms over the next ten days, with each of these storms moving northwards across Cuba, South Florida, and the Bahamas. The first of these storms would organize on Monday, moving over South Florida by Wednesday, and would likely be at strongest a 50-mph tropical storm. The Hurricane Hunters are on call to investigate anything that might develop over the Western Caribbean on Monday afternoon. NHC is giving a 10% chance that something might develop in the Western Caribbean by Wednesday.

I'll have an update Monday morning.

Jeff Masters

Hurricane

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