Now, Florida faces more flooding as Tropical Storm Nicole is poised to hit the East Coast and move up the state.

But North Carolina State University researchers say federal flood maps underestimate the risks of flooding in Florida and other states. And that can lead many homeowners to ignore buying flood insurance — a decision that many people might be regretting as they try to clean up water-damaged homes after Ian.

"Following Ian, and many other major hurricanes, we have observed serious flood damage beyond the boundaries of the 100-year floodplain," Georgina Sanchez, a research associate at the university's Center for Geospatial Analytics, said in a prepared statement. "This suggests that there are communities across the nation susceptible to damage that our current flood management policies don't consider."

Residents who have mortgages on properties in federally designated flood zones are required to buy flood insurance, which is mostly purchased through the National Flood Insurance Program. But most Floridians don't have flood insurance, exacerbating problems from Ian, which made landfall Sept. 28 as a Category 4 storm in Lee and Charlotte counties before crossing the state.

CoreLogic, a property-information and analytics firm, estimated in early October that Floridians could have more than $10 billion in uninsured flood losses from Ian. Standard homeowners' policies don't cover flood damage.

Forecasters are predicting heavy rainfall and storm surge from Nicole, which was upgraded Tuesday morning to a tropical storm and could make landfall in Florida as a hurricane. The National Hurricane Center issued a hurricane warning Tuesday from Boca Raton to the border of Flagler and Volusia counties.

An advisory from the center also warned about flooding outside of coastal areas as the storm moves through Florida into Georgia.

"Flash and urban flooding will be likely, along with possible renewed river rises on the St. Johns River, across the Florida peninsula on Wednesday and Thursday," the advisory said.

The North Carolina State research published in February used artificial intelligence to predict where flood damage is likely to happen. Among other things, researchers found a "high probability" of flood damage for more than 1.01 million square miles across the country. That is substantially more territory than 221,000 square miles included in FEMA maps of the 100-year floodplain, according to the university.

"FEMA's designation of high-risk flood zones can mislead communities about their actual risk and encourage development that borders the floodplain, resulting in greater damages when flood events exceed design levels," Sanchez said in a statement.

FEMA is required to review communities' flood maps every five years and decide whether to change them, according to a monthly report submitted in September to Congress. Areas in the 100-year floodplain are defined as having a 1 percent chance of flooding in a given year.

But the information released last week by North Carolina State said "FEMA's flood maps underestimate the risk of flooding by failing to account for intense rainfall events and sea level rise. These conditions are becoming more common as climate change accelerates, increasing the likelihood and seriousness of flooding."

As of August, Florida had about 1.64 million policies in the National Flood Insurance Program, the most of any state, data posted on the FEMA website shows. The program had received more than 44,000 claims from Ian as of Sunday and paid out $351 million to policyholders.