Deadly Tropical Storm Erika weakened as it drenched Haiti and the Dominican Republic early Saturday, but Florida officials still want residents to be prepared.

Despite uncertainty over the storm’s path and intensity, Florida Gov. Rick Scott declared an of emergency on Friday for the entire state.

The westward trend of disorganized #Erika continues. Over 24” rain reported in the D.R. http://t.co/asztfhpaLO pic.twitter.com/ygUcnenVWW — The Weather Channel (@weatherchannel) August 29, 2015

At least 20 people were killed in the aftermath of the storm as it passed over the Carribean island country of Dominica on Friday, its prime minister said, describing extent of the devastation as “monumental.”

In an address to the nation, Prime Minister Roosevelt Skerrit said many others are still missing. More than a foot of rain fell in less than 12 hours as the storm hit Wednesday. Torrents of water flowed through streets and swept away cars.

“This is a period of national tragedy,” he said.

The center of Tropical Storm Erika is “still very poorly organized,” the Weather Channel said Saturday, but tropical storm warnings continue in Haiti, the Turks and Caicos, and the central and southeast Bahamas.

Officials in Florida said residents should prepare by filling vehicles’ gas tanks, stockpiling a few days’ of food and water, and determining whether they live in an evacuation zone. The storm has the potential to rake Florida’s west coast with heavy rains starting late Sunday or early Monday.

Chris Landsea, a meteorologist with the National Hurricane Center, says Erika is an “extremely disorganized storm,” which is making it difficult for forecasters to track. A hurricane is stronger, better formed and has an eyewall. Hurricanes also have a more regular motion pattern, unlike tropical storms, which can be large blobs of weather.

“For track prediction, it’s actually easier to track a strong hurricane than a sloppy tropical storm like Erika,” Landsea said.

This story originally appeared on NBCNews.com