Storm Erika's Next Two Days Decides U.S. East Coast Threat

  • Storm will need to survive pass over Hispaniola's mountains
  • Forecasts unclear on Erika's future beyond next two days

Tropical Storm Erika will approach the Dominican Republic on the Caribbean island of Hispaniola Friday and whether it survives will determine if it will threaten the U.S. East Coast.

Erika, 145 miles (230 kilometers) southeast of San Juan, Puerto Rico, had top winds of 45 miles per hour and was forecast to reach Puerto Rico late Thursday, the U.S. National Hurricane Center said in an 8 p.m. New York time advisory. It will then cross Hispaniola, where it will run into mountains and wind shear.

Mountains can rip storms apart, as can the varying wind speeds at different altitudes typical of wind shear environments.

“Beyond that time, the shear is forecast to relax somewhat, and this could allow for intensification, assuming that the cyclone is not too disrupted by the mountainous land mass of Hispaniola,” Richard Pasch, a senior hurricane specialist at the Miami-based center, said in a forecast analysis.

Erika, the fifth storm of the six-month Atlantic season, is being blamed for four deaths on the Caribbean island of Dominica, the Associated Press reported. As much as 12 inches (30 centimeters) of rain fell there, Pasch said.

Uncertain Threat

The inability to know what shape Erika will be in after a forecast brush with Hispaniola has made it hard to determine whether it’ll pose a threat to the U.S.

“There is unusually high uncertainty in the forecast intensity, especially at days 3 to 5,” Pasch wrote.

The current forecast calls for Erika to be a Category 1 hurricane on the five-step Saffir-Simpson scale by Tuesday.

There is also a chance that Erika won’t survive the trip at all, said Dan Kottlowski, a meteorologist at AccuWeather Inc. in State College, Pennsylvania.

“Very few storms of this caliber survive interaction with Hispaniola like this,” Kottlowski said by telephone. “This is a very complex situation.”

If Erika survives its trek across the Caribbean, no one should take it lightly, Joe Bastardi of WeatherBell Analytics LLC said in a note to clients Thursday. In El Nino years, such as this one, there have been numerous examples of ragged storms breaking through wind shear and menacing the East Coast.

El Nino

During El Ninos, a warming in the equatorial Pacific, wind shear rises in the parts of the Atlantic that can keep storms from forming or tear them apart. Bastardi said conditions close to the U.S. can often become favorable, allowing strong storms to form there.

“There are examples of El Nino season storms busting troughs, and when they do, look out,” Bastardi said.

Wednesday, Florida’s Division of Emergency Management said it’s preparing for a brush with Erika and told residents to review their own plans on what to do if a storm strikes. The state was last hit by a hurricane in 2005.

More immediately, tropical storm warnings and watches cover parts of many islands including the Bahamas, Puerto Rico and the U.S. and British Virgin Islands. Erika may bring 4 to 8 inches of rain across the area, with some isolated locations getting up to 12 inches.

Drought Conditions

Puerto Rico is in the grips of drought, with about 87 percent of the island abnormally dry or worse, according to the U.S. Drought Monitor in Lincoln, Nebraska. A flash flood watch had been posted for both Puerto Rico and the U.S. Virgin Islands.

“Localized flash flooding and land slides are possible in areas of high intensity tropical downpours,” the National Weather Service said.

In the Pacific, Hurricane Ignacio may become a Category 3 storm by Friday, the hurricane center said. It is forecast to pass north of the Hawaiian islands Tuesday and is currently located about 1,055 miles east-southeast of Hilo, Hawaii.

Farther to its east, Tropical Storm Jimena, far from any landmass, is forecast to grow into a major hurricane by Sunday.

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