CoreLogic has released preliminary data showing that 808,321 single-family and multifamily homes along the Florida Gulf Coast with a reconstruction cost value (RCV) of approximately $238.4 billion are at potential risk of storm surge damage from Hurricane Idalia (these figures were assessed assuming Hurricane Idalia made landfall as a Category 3 hurricane, based on the National Hurricane Center’s August 29th forecast).
As of Wednesday morning, according to the National Hurricane Center, when the storm finally made landfall, Hurricane Idalia had maximum sustained winds of 90 miles per hour, with stronger gusts, downgrading it to a Category 1 hurricane, as the center of the storm crossed into southern Georgia.
As of noon EST Wednesday, CNN reports that a flash flood emergency was issued for the Florida Counties of Brooks and Lowndes, including Valdosta, until 12:45 p.m. ET. Between three to six inches of rain have fallen already from Hurricane Idalia, and additional amounts of one to two inches are expected Wednesday afternoon and evening.
CNN also reports that water levels on the Steinhatchee River, in the town of Steinchatchee in Florida’s Big Bend region, near where Hurricane Idalia made landfall, rose more than nine feet in nearly two hours on Wednesday morning.
The National Weather Service expects extensive and intense rainfall across northern Florida, as well as coastal George and the Carolinas. A moderate (at least 40% chance) flash flood risk is possible through Friday, Sept. 1, especially in urban environments such as Jacksonville, Florida; Savannah, Georgia; Charleston, South Carolina; and Wilmington, North Carolina. A slight flash flood risk (at least 15% chance) extends as far inland as Chattanooga, Tennessee; and Atlanta.
Surge depths are forecasted to reach eight- to 12-feet above ground surface from the Aucilla River in the Apalachee Bay to the Chassahowitzka River in Florida’s Citrus County. Storm surge depths of four- to seven-feet above ground surface are possible in the Tampa Bay–St. Petersburg area.
“Due to the sparsely populated forecasted impact area, there will likely be a lower insured loss ceiling from Idalia, compared to last year’s Hurricane Ian,” said Jon Schneyer, Director of Catastrophe Response, CoreLogic. “Even so, systems that make landfall along the Gulf Coast are likely to generate a more substantial storm surge than equivalent storms that hit the Atlantic Coast. As such, Hurricane Idalia is expected to bring hurricane-force winds, catastrophic storm surge of up to 15 feet, and widespread inland flooding across Florida and the southeastern U.S.”
CoreLogic estimates that last October’s Hurricane Ian brought damage and loss totals from total flood and wind losses between $41 billion and $70 billion. The estimate includes wind loss, re-evaluated insured and uninsured storm surge loss and newly calculated inland flood loss for residential and commercial properties. Hurricane Ian, to date, is the costliest Florida storm since Hurricane Andrew made landfall in 1992.
The chart is a breakdown of the residential single family and multi-family homes at risk of storm surge damage in Florida, and as Hurricane Idalia approaches Florida, its path is anticipated to become more certain, and the below metropolitan areas at risk will narrow:
The table above indicates a subset of the total 808,321 buildings. A damaged structure may not sustain 100% loss up to the full RCV. The RCV figures presented above represent the cost of completely rebuilding the existing residential structure. The RCV amount includes the costs of materials, equipment, and labor, but does not include the value of the land or lot.
Hurricane-driven storm surge can cause significant property damage when high winds and low-pressure cause water to amass inside the storm, releasing a powerful rush over land when the hurricane moves onshore.