Developing Tropical System Headed for Caribbean

By Michael D. Lemonick

UPDATE, 5 P.M. EASTERN STANDARD TIME

The National Hurricane Center has just upgraded Tropical Depression 5, renaming it Tropical Storm Ernesto. It's now the fifth named storm of the current season. The upgrade was based on new observations of tropical-storm-force winds by an Air Force Reserve Hurricane Hunter aircraft. The projected track into the Caribbean remains unchanged so far.

ORIGINAL STORY

For now it’s known only as Tropical Depression 5, or TD5 — an organized group of thunderstorms, located several hundred miles northwest of South America and making its way due west, toward the Windward Islands that mark the boundaries of the Caribbean Sea. Within 48 hours, however, TD5 could tighten to become Tropical Storm Ernesto, the fifth named storm of the season. If sustained winds eventually shoot above 74 mph, we’ll be talking about Hurricane Ernesto, and it could spell big trouble for parts of the Caribbean several days from now. However, there are lots of uncertainties in the forecast.

Enhanced infrared satellite view of the Tropical Atlantic, showing the small tropical depression near the bottom center of the image.
Credit: NOAA

Whether Ernesto develops depends on the weather conditions surrounding TD5. According to the latest report by Weather Channel senior meteorologist Stu Ostro, the tropical depression is now struggling for survival against an influx of dry air and atmospheric wind shear. “During its formation,” Ostro wrote, “TD 5 had been in favorable atmospheric conditions, underneath relatively weak upper level winds, and avoiding most of the dry air and wind shear that's been around over the Atlantic during the past several weeks, but it is now having more trouble avoiding those hostile conditions.” In plain English, that means TD5 could degenerate into a more or less ordinary tropical wave, which would bring gusty squalls to the Windward Islands, but nothing very damaging.

Either way, wind and heavy rain should hit the Lesser Antilles, which includes Barbados, Trinidad and Martinique, by Friday. After that, said research meteorologist Brian McNoldy on his Tropical Atlantic Update blog, “As far as the track forecast goes, there's a bit of spread in the models, but they generally agree on a trek across the Caribbean, so Hispaniola, Jamaica, Cuba, etc. should be watching this VERY closely.”

Hurricane experts will also be watching the Atlantic vigilantly for the next tropical depression, since August and September are typically the busiest months for Atlantic tropical storms and hurricanes.

As of Thursday, the U.S. had not been struck by a major hurricane – Category 3 or above with sustained winds of 111 mph or greater—in a record 2,475 days. The last major hurricane to make landfall in the U.S. was Hurricane Wilma in October 2005, which struck Southwest Florida.