MIAMI, (Reuters) – Tropical Storm Erika weakened as  it edged over the Leeward Islands of the northeast Caribbean yesterday but it threatened to douse them with heavy rainfall,  the U.S. National Hurricane Center said.The fifth tropical storm of the 2009 Atlantic hurricane  season had sustained winds of 40 miles per hour (65 km per  hour), down from 50 miles per hour (80 km per hour) when it  formed in the Atlantic on Tuesday.

Strong winds in the upper atmosphere were stifling the  poorly organized storm. Forecasters expected Erika to weaken to  a tropical depression, with winds below 39 miles per hour (63  km per hour), today.