Florida governor Rick Scott declared a state of emergency on Friday as forecasters predicted Tropical Storm Erika would make landfall in Miami, perhaps as early as Monday.

Scott warned that the windstorm posed "a severe threat to the entire state" and ordered the activation of the National Guard and other emergency teams.

Erika has already left several people and dead on the Caribbean island of Dominica. The small mountainous territory was lashed by heavy winds and rain on Thursday, and Erika is due to hit the Dominican Republic on Friday.

"The latest trajectory models indicate that the Dominican Republic will see a direct hit from Erika," according to Gloria Ceballos, director of the National Meteorological Office.

The Miami-based National Hurricane Center warned of "life-threatening flash floods and mudslides" for the north of Haiti. The Caribbean island of Hispaniola, just southeast of Cuba, is shared by Haiti and the Dominican Republic.

Forecasters say Erika is unusually hard to predict, due to disruption from wind patterns and its behavior over land.

Dominica damage

America's CBS News quoted an official in Dominica as saying the death toll had reached 20, with several people still missing after mudslides destroyed dozens of homes.

Most of the island of Dominica remained without power or water on Friday, officials said. Overflowing rivers and landslides washed away several roads and bridges.

The airport was also closed due to flooding. Rescue teams said they were still unable to reach some areas in the southeast.

Fears that Erika could turn into a full-force hurricane as it approached Florida were played down by US meteorologists on Friday.

They said the Miami area could still be struck by 97-kilometer-per-hour (60-mph) winds and warned residents that the storm could regain strength after it crossed the Bahamas. If it does become a hurricane, it would be the first to hit Florida in a decade.

Gov. Scott urged residents to follow news reports, adding that the situation was changing by the hour. He said that the storm could travel "up the spine of Florida" into next week.

In Puerto Rico, around 200,000 people remained without power, but Erika spared the island any significant damage as it made landfall on Friday.

mm/jm (AP, dpa, Reuters, CBS News)