By Dave Sherwood and Nelson Acosta ARTEMISA, Cuba (Reuters) -Cuban authorities said they had begun restoring power to the eastern half of the island on Thursday, a day after Hurricane Rafael knocked out the country's electrical grid,

The hurricane center cautioned there is "larger-than-normal uncertainty regarding Rafael's intensity later in the forecast period."

The National Hurricane Center said Hurricane Rafael grew into a major Category 3 storm Wednesday and made landfall in Cuba on its way into the Gulf of Mexico, while the Florida Keys remained under a tropical storm warning.