Tropical Storm Emily brushed past Puerto Rico and headed Wednesday toward the Dominican Republic and Haiti, where more than 630,000 people are still without shelter after last year’s earthquake.

A “steady shield of rain” should reach the island of Hispaniola shared by the Dominican Republic and Haiti around noon Wednesday and the rainfall should worsen by late afternoon, said John Dlu-goen-ski, senior meteorologist with Accuweather.com.

“The biggest threat to lives is probably the flooding,” Dlu-goen-ski said.

But it appears the worst of the storm will largely spare Haitian capital, where most of the quake victims are sheltered.

Michel Davison of the U.S. National Oceanic and Atmospheric Administration said parts of the Dominican Republic could see up to 20 inches (50 centimeters) of rain over the next 36 hours. Up to 10 inches (25 centimeters) is expected in rural Haiti and up to 6 inches (15 centimeters) in the capital.

Civil defense officials and the military in the Dominican Republic have already begun moving people out of high-risk zones ahead of the storm. Haitian authorities urged people to conserve food and safeguard their belongings.

In Haiti’s capital of Port-au-Prince, Jislaine Jean-Julien, a 37-year-old street merchant displaced by the January 2010 earthquake, said she was praying the storm would pass her flimsy tent without knocking it over.

“For now, God is the only savior for me,” Jean-Julien said at the edge of a crowded encampment facing the quake-destroyed National Palace. “I would go some place else if I could but I have no place else to go.”

Haitian emergency authorities set aside a fleet of 22 large white buses in the event they needed to evacuate people from flooded areas. Emergency workers would then bus the people to dozens of schools, churches and other buildings that will serve as shelters.

“We’re working day and night to be able to respond quickly in case we have any disasters,” said Marie Alta Jean-Baptiste, director of Haiti’s Civil Protection Agency.

Emergency workers, both Haitian and foreign, also sent out text messages to cell phone users, alerting them to the approaching storm and to take precautions such as staying with friends or relatives if that were an option.