Forecasters believe Ian will spend days dumping rain on Florida after making landfall as a hurricane, which could cause widespread flooding and damage.
The storm is expected to slow to a crawl as it approaches land, resulting in extended rainfall of up to 2 feet in some areas, with localized flooding.
According to the National Hurricane Center’s forecast on Tuesday, the storm will move slowly through the state from Wednesday to Friday.
According to Anthony Reyes of the National Weather Service in Miami, Ian is expected to affect the entire state, with areas in its direct path expected to see widespread damage and winds of well over 100 mph. Furthermore, coastal areas along the Gulf of Mexico are more vulnerable to storm surge flooding.
According to the National Hurricane Center, parts of Central Florida could receive 12-16 inches of rain, with up to 2 feet possible in isolated areas. Other parts of the state may receive 6 to 8 inches of snow, with isolated areas receiving up to a foot.
Some areas on the state’s western coast, such as Charlotte Harbor, should expect 8-12 feet of storm surge, according to the center.
“There will be catastrophic flooding and life-threatening storm surge in some areas,” Gov. Ron DeSantis said Tuesday.
Ian is expected to make landfall in Florida between Tampa and Fort Myers, then move through Central Florida as it weakens. When it hits, it will already be moving at 5 mph, implying that its path through the state will be slow.
“When these kinds of systems slow down, it allows for a longer period of time for the same locations to receive rain,” Reyes explained. “This increases the possibility of localized flooding.”
According to Reyes, the concentrated metro areas in the storm’s path are especially vulnerable. Flash flooding and urban flooding are expected in central and northern Florida, southern Georgia, and coastal South Carolina this week.
Tens of thousands of stormwater ponds, which are built in developed areas to collect and store stormwater runoff, are part of Florida’s flood management system.
A “buffer” may help reduce flooding impacts in residential and commercial areas where stormwater ponds are common, according to Eban Bean, an assistant professor in the University of Florida’s Department of Agricultural and Biological Engineering.
“While they won’t be able to catch all of this stormwater volume, they will help by slowly releasing that water downstream rather than letting it all come at once whenever the rain is at its heaviest,” Bean explained.
Even so, the stormwater ponds were not designed to handle the amount of rainwater expected with Ian, and the extra volume will most likely cause flooding that will last until the mitigation systems drain it out. However, communities in Ian’s path that have stormwater ponds, such as Lakewood Ranch, which has over 300, may fare better than those that do not.
The National Weather Service in Miami warned that structural damage caused by hurricane-force winds in some areas of the state could render some residential buildings “uninhabitable” for weeks or even months.
Because of Florida’s relatively flat topography, water may take several days to drain completely, according to Bean. Bean added that recovery is also dependent on subsequent weather activity; if other tropical systems form, it could take much longer.
“This will be a test of our (stormwater management) system,” Bean explained.