ST. PETERSBURG, Fla. — The National Hurricane Center said Friday that Tropical Storm Erika is forecast to weaken into a tropical depression.

In their 5 p.m. announcement, meteorologists said they expect Erika to be downgraded to a depression Saturday. There’s even a possibility that the storm could dissipate to a trough of low pressure during or after its passage over Hispaniola.

Officials say there’s “a significant chance” that no watches or warnings for Florida will be required over the weekend.

Still, the storm has the potential to rake Florida’s west coast with heavy rains starting late Sunday or early Monday. Although the storm’s path and intensity are a bit uncertain, Florida Gov. Rick Scott declared a state of emergency on Friday for the entire state. Officials say 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.

Meteorologists at the National Hurricane Center in Miami say several factors come into play over the next 24 hours that will determine whether Erika is little more than a rainstorm for the Sunshine State.

Chris Landsea, a meteorologist with the National Hurricane Center, said Tropical Storm Erika is an extremely disorganized storm, so it is difficult for forecasters to track. A hurricane is stronger and better formed, and has an eye wall. 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.

Ocean water in the Pacific is actually affecting Erika in the Caribbean. Meteorologists say the weather pattern of warm ocean water weakens storms in the Atlantic. El Nino is one reason behind a quiet hurricane season overall this year.

Erika is “fighting for its life right now,” said MIT meteorology professor Kerry Emanuel. He said there’s a small possibility that Erika could intensify but called that unlikely. That’s because strong winds aloft are weakening the storm – called wind shear – and that’s typical for years with an El Nino, like the current one.

Given how weak the storm is and how dry Puerto Rico and parts of Florida have been, “it could be a net benefit,” Emanuel said.

Erika is forecast to pass near, or over, the tall mountains of the Dominican Republic. It could easily break apart over that terrain, forecasters say.

Because this storm is so difficult to forecast, it’s unclear where, or whether, it will make landfall in Florida. Meteorologists say the potential for heavy rainfall, flooding, rip currents and storm watches/warnings will emerge over the weekend as the system moves closer to the U.S.

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