Tropical Storm Sandy grew into a hurricane just south of Jamaica as the odds increased for a brush with the U.S. East Coast next week.
Sandy was about 30 miles (48 kilometers) south of Kingston with top winds of 80 miles per hour, according to an 2 p.m. New York time advisory from the U.S. National Hurricane Center. It is a Category 1 hurricane, the weakest on the five-step Saffir- Simpson scale.
“Conditions appear favorable for additional intensification until the cyclone moves near or over eastern Jamaica,” Michael Brennan, a senior hurricane specialist at the center, said in an analysis.
Winds on Jamaica will build through the day and as much as 6 to 12 inches (15 to 30 centimeters) of rain might fall, which may trigger landslides and flooding, according to the Meteorological Service of Jamaica. As much as 20 inches may fall in isolated areas of Cuba, Haiti and the Dominican Republic.
Sandy is expected to strike Cuba later today and then the Bahamas, and has the potential to bring tropical storm conditions to southern Florida, including Miami. The system may threaten the U.S. East Coast next week and eventually go ashore in New England as a burst of cold air also enters the region.
Commodity Weather Group LLC President Matt Rogers said he gives Sandy about a 55 percent chance of hitting somewhere in the six New England states, which include Connecticut and Massachusetts. Other meteorologists in his office have greater doubts about such a track, he said.
“This is a really tricky situation,” Rogers said in an e- mail interview from Bethesda, Maryland.
The storm has the potential to bring snow to the Appalachians from New England south to the Mid-Atlantic states, because cold air may mix with the moisture coming off the ocean as Sandy arrives, Rogers said. Cities on the coast, including New York, Philadelphia and Boston, wouldn’t see snow in this scenario, he said.
The hurricane center’s official storm track only extends to Oct. 29 and shows Sandy edging to the northeast into the Atlantic.
The difficulty for forecasters is that they have to predict what upper-level air features are going to come into play in about a week’s time, said Paul Walker, an expert senior meteorologist at AccuWeather Inc. in State College, Pennsylvania.
In one scenario, Sandy is pulled into the East Coast by weather systems over the U.S., Walker said. In an alternative, U.S. weather patterns push the storm away from the coast.
“It is still too early to tell,” Walker said. “The upper-air features aren’t quite clear on how this storm will behave.”
The Massachusetts Emergency Management Agency said residents should monitor the storm’s progress.
Hurricane warnings are in effect for Jamaica and eastern Cuba, meaning “preparations to protect life and property should be rushed to completion,” the NHC said.
A hurricane watch was issued for Haiti and the northwestern and central Bahamas, where winds and heavy rain are expected in about 36 hours. A tropical storm watch is in place for the southeastern Bahamas and southern Florida and the Florida Keys.
A watch means storm conditions are possible in about two days. Sandy’s hurricane-strength winds of at least 74 mph extend 25 miles from its center while its tropical storm strength reaches 140 miles.
Walker said wind and rain may reach southern Florida starting tomorrow. As much as 3 inches of rain may fall in Florida.
In addition to Sandy, Tropical Storm Tony has formed in the central Atlantic, making 2012 the third year in a row that 19 storms have developed. That ties 2012 for the third-most active season, with 2010, 2011, 1995 and 1887.
Tony is expected to remain far from land.
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