FOX Weather Hurricane Specialist Bryan Norcross says Tropical Storm Debby appears bound for the Big Bend region of Florida, but the future becomes cloudier after landfall.
Given Florida’s distinctive coastline, its topography makes it particularly vulnerable to storm surge flooding during hurricanes and other significant storm systems.
Storm surge refers to the increase in water levels directly attributed to the cyclone, excluding additional contributions from rainfall or wave size, which can further elevate the surge even more.
Due to the threats posed by Debby, a Storm Surge Warning has been issued from roughly the Apalachicola River to north of the Tampa metro area.
(FOX Weather)
It is within this zone that the National Hurricane Center expects the worst of the tidal flooding to occur.
Forecast models indicate there could be a storm surge rise of 4 to 7 feet for communities around Horseshoe Beach and Cedar Key.
The shape of the coast and the shallow shelf waters allow water to funnel in during even the weakest of storms, making the area one of the most surge-prone regions in the country.
Storm Surge map for the Panhandle and Big Bend of Florida
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If the forecast holds, the surge will be significant but not exceed the values observed during Hurricane Idalia less than a year ago.
Idalia made landfall along Florida’s Big Bend as a Category 3 cyclone and produced a storm surge of 7-12 feet.
In many locations, the values were the highest levels seen since the Storm of the Century in 1993.
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Birds float in the flooded water near the Steinhatchee Marina in Steinhatchee, Florida, on August 30, 2023, after Hurricane Idalia made landfall. (Photo by CHANDAN KHANNA / AFP) (Photo by CHANDAN KHANNA/AFP via Getty Images) (Photo by CHANDAN KHANNA/AFP via Getty Images)
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Flooding from Idalia in Charlotte County in southwest Florida. (Charlotte County Emergency Management / Facebook)
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Flooding in Hernando Beach, Florida from Idalia. August 30, 2023. (Hernando County Sheriff’s Office / Facebook)
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Flooding in Hernando Beach, Florida from Idalia. August 30, 2023. (Hernando County Sheriff’s Office / Facebook)
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A flooded street is seen near the Steinhatchee marina, Florida on August 30, 2023, after Hurricane Idalia made landfall. (CHANDAN KHANNA/AFP)
NOAA forecasters said the hurricane’s surge could have been 3 to 4 feet higher if Idalia had moved onshore during a period of high tide.
Features such as the low and high tide cycles and the status of the Moon can impact how water levels rise.
Due to Earth’s rotation, coastal communities experience two high tides and two low tides every 25 hours, which can mean a difference of upwards of around four feet for coastal communities such as Ceder Key.
A new moon cycle, like the one currently underway, contributes to a water rise, but it is less significant when compared to the King Tides that occur during supermoons.
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NOAA says storm surge is often the greatest threat to life and property during hurricanes and accounts for nearly half of the deaths associated with the landfall of a tropical cyclone.
In 2022, Hurricane Ian made landfall in Southwest Florida, causing at least 156 fatalities along its path of destruction.
According to NOAA data, nearly 60% of those who died in the hurricane drowned, with many in the storm surge zone.
Fortunately, ahead of Debby, areas heavily impacted by Ian and significant population centers such as Tampa and Fort Myers are expecting a storm surge of 4’ or less.
Storm surge map during Debby for Central and South Florida
(FOX Weather)
The combination of heavy rainfall at high tide can lead to additional flooding that surge warnings and watches do not account for.
Communities facing this threat would be placed under what is known as a Flash Flood Warning, which would remain in effect until water levels recede.