TROPICAL STORM ETA FORECAST TO BECOME A HURRICANE IN THE CARIBBEAN – BIG LONG-RANGE QUESTION MARKS

The Tropical Disturbance we’ve been following through the Caribbean gained enough organization to be designated Tropical Depression Twenty-Nine late yesterday and then quickly strengthened into Tropical Storm Eta last night. This officially ties 2005 for the most storms of at least tropical-storm strength. But this year, we reached that milestone almost 2 months earlier than in that mega year that included Hurricanes Katrina, Rita, and Wilma.

The atmospheric environment in the Caribbean is fairly supportive of tropical development and the seawater there is still very warm, so the National Hurricane Center is forecasting Eta to steadily intensify and become a hurricane in a day or two when it arrives near the coast of Nicaragua and Honduras.

Hurricane Watches are in effect for coastal sections of those countries with landfall expected late Tuesday or early Wednesday.

The forecasts for rain over the mountainous areas are ominous – up to 30 inches. Some of the deadliest hurricanes in history – like Hurricane Mitch in 1998 – produced intense rainfall over those countries due to massive landslides cascading down the mountains. Heavier rain falls at high elevations, the wet earth gives way, and it falls in an avalanche of mud and debris. Hopefully they can somehow prepare.

The big question for us is, what happens after landfall.

The official National Hurricane Center forecast steers Eta into the mountains of Central America where it weakens or dies out. That appears to be the highest probability outcome. But even that might not end the story.

By Thursday or Friday, most of the computer forecast models predict a low-pressure system will organize in the western Caribbean near the Honduras coast. Because it shows up in so many models, we have to be cognizant of that possibility.

Eta is being driven west by high-pressure sprawled across the western Atlantic. And now, the strong high-pressure system behind the robust cold front that will push through South Florida tonight will add to the main high and likely push Eta into Central America where it will weaken or die out.

The atmospheric environment over the western Caribbean will continue to be supportive of tropical development, however. So it’s possible a new system will form in the same general vicinity, but over the water, perhaps including some of Eta’s spin.

Whether it would be Eta-reborn or a different system is impossible to say. If the second system develops, the National Hurricane Center would track Eta’s low-level circulation to determine if it survived its interaction with the Central American mountains or not.

If it did not, and the new system gained winds of 40+ mph, it would be called Tropical Storm Theta. If they could track the original circulation and it simply restrengthened, it would still be Eta.

None of this is very far in the future, if it happens. We might see hints late Thursday or Friday if a new system is going to develop.

An annoying factor in all this is that a big dip in the jet stream is coming along late in the week that will want to pull whatever’s in the western Caribbean north. Whether that’s just tropical moisture, or it’s an organized system, is impossible to predict. We’ll be watching developments closely late in the week and over next weekend.

For now, get out and vote in the nice weather. There’s nothing to do but monitor the situation, and think about our friends in Central America. Sadly, it’s mostly poor folks that live in mudslide zones, and they often lack the resources to move very far.