 In response to the formation of Irene, tropical storm warnings were issued for all of the Leeward Islands and Puerto Rico.Also in the Lesser Antilles, the storm's approach prompted authorities in the U.S. Virgin Islands to close off air- and seaports, as well as to open public shelters.As Irene was forecast to make landfall on Hispaniola, a tropical storm watch was initially issued for the south coast of the Dominican Republic, though it was upgraded to a hurricane warning on August 21, after strengthening was forecast.