Dirty work: How Hurricane Idalia sent 200 miles of storm surge down the west coast of Florida
When Hurricane Idalia collided with the rural Big Bend region of Florida at 7:45 a.m. on Aug. 30, it heaved nearly 10 feet of storm surge into the two nearest coastal towns, Steinhatchee and Cedar Key.
Ninety miles south of landfall, in Crystal River, the surge was so bad that authorities had to take an airboat to tour the town’s streets.
And even 150 miles away, the storm pushed more than 4 feet of surge into Tampa Bay. One man paddled a pool floaty over what was once a promenade. Navin Singh, of Tampa Bay Storm Chasers, watched water crest a 6-foot seawall, flooding volleyball courts and streets. It was the largest surge Tampa had seen since the 1921, when, according to the National Oceanic and Atmospheric Administration, the Tampa Bay/Tarpon Springs Hurricane brought 11 feet of storm surge to the city.
Idalia’s surge was able to reach Naples, some 250 miles south as the crow flies from landfall, flooding streets and construction sites.
Here’s a look at the factors that allow a relatively compact storm such as Idalia to send surge down nearly the entire west coast of Florida, and the strokes of luck that kept the damage from being worse.
Surge and the dirty side
Hurricanes in the northern hemisphere all rotate counterclockwise, explained Brian Haus, director of the SUSTAIN Laboratory at the University of Miami. Haus and his team use a massive water tank to simulate and study storm and ocean interactions.
As a storm moves forward, its right-hand side is more destructive, and is known colloquially as the “dirty” side. Surge, therefore, is far worse on the right-hand side of a storm. Idalia’s landfall in the Big Bend region put everything south of that point on the dirty side.
The closest town to landfall on the dirty side of Idalia was Steinhatchee, 15 miles south, which saw just over 9 feet of surge, according to the Suwannee River Water Management District.