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MIAMI, Oct 12 (Reuters) - Tropical Storm Nana, the 14th of the Atlantic hurricane season, formed on Sunday in the Atlantic Ocean east of the Caribbean islands, the U.S. National Hurricane Center said.

It said the storm was likely to be short-lived as it curved west-northwest over open waters in the Atlantic over the next day or two, well away from the small and vulnerable islands of the Caribbean and from the U.S. mainland.

At 5 p.m. EDT (2100 GMT), Nana was centered 925 miles (1,485 km) west of the Cape Verde Islands with top sustained winds of 40 mph (65 kph), the Miami-based hurricane center said.

It said the storm was expected to weaken to a tropical depression late on Sunday or Monday and had only a "bleak" prospect of longer-term survival.

The six-month hurricane season, which runs from June 1 to Nov. 30, has been a busy one although it has lapsed into a recent lull.

Of the 14 tropical storms that have formed to date, six have become hurricanes. The long-term Atlantic season averages are about 10 tropical storms and six hurricanes.

It has also been a deadly and damaging season.

More than 800 people were killed in Haiti, mostly by floods, as the impoverished Caribbean nation was swamped by Fay, Gustav, Hanna and Ike in a month.

Gustav and Ike disrupted U.S. oil and natural gas production in the Gulf of Mexico before slamming ashore in Louisiana and Texas, respectively. (Reporting by Tom Brown; Editing by Philip Barbara)

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