(Adds detail on forecast track and quote from National Hurricane Center)
MIAMI, Aug 24 (Reuters) - Tropical Storm Cristobal formed near the southeastern Bahamas on Sunday and is moving to the northwest with winds near 45 miles per hour (72 km per hour), the U.S. National Hurricane Center said.
Centered about 40 miles (64 km) north of Mayaguana Island Cristobal was moving at almost nine mph (14 kph) and could strengthen into a hurricane over the next four days, it reported.
"The pressure has dropped, which indicates the storm is getting stronger, said Chris Landsea, a meteorologist at the National Hurricane Center in Miami. "It's still not very well formed."
Cristobal is the third named storm of the Atlantic hurricane season and is forecast to turn in a more northerly direction later Sunday and Monday, taking it over the central Bahamas.
Longer-range forecasts show it gradually strengthening while staying well offshore as it turns to the northeast, skirting the North Carolina coast on Thursday and Friday before spinning away over the Atlantic.
"Folks in the southeast U.S., the Carolinas in particular, need to monitor this," said Landsea.
Cristobal drenched parts of Haiti and the Dominican Republic on Saturday, and also provided some relief to drought conditions in Puerto Rico, replenishing key water resources for the capital San Juan.
Forecasters in August downgraded their outlook for the 2014 Atlantic hurricane season, predicting below-normal activity with seven to 12 named storms, and no more than two expected to reach major hurricane status.
A major hurricane is considered to be Category 3 or above with winds hitting at least 111 mph (178 kph).
So far this year two hurricanes - Arthur and Bertha - have developed in the Atlantic. Only Arthur, a Category 2 storm, made landfall, on North Carolina's Outer Banks in early July.
Cooler-than-average temperatures in the tropical Atlantic Ocean are making it difficult for larger storms to develop, the forecasters say. (Reporting by Zachary Fagenson in Miami and Eric Beech in Washington.; Editing by David Adams, Andrew Roche and Lynne O'Donnell)