Storm surge: Hurricane Ian’s most powerful impact

Storm surge flooding out portions of Downtown Fort Myers. The surge from Ian traveled 15 miles inland to flood the downtown area. (Photo by Joe Raedle/Getty Images) (Getty Images)

JACKSONVILLE, Fla. – As the push to survey storm damage in Southwest Florida continues, it is becoming clear what was Ian’s most powerful and deadly characteristic -- storm surge.

Hurricane Ian was able to create an incredible storm surge, which covered the barrier islands of Southwest Florida in several feet of water and pushed all the way into Downtown Fort Myers.

Storm surge is the number one concern among meteorologists during hurricanes because of its power and deadly consequences.

What is storm surge?

Example of storm surge moving onto land.

Storm surge is when water from the ocean or a bay lifts onto land during a tropical system.

The surge is a result of the high winds, low barometric pressure and surf that a tropical system creates.

The best way to think about storm surge is water in the bathtub.

When you push on water in a tub, the water will eventually splash onto the edges of the bathtub. If you push even harder, water will eventually spill over onto the floor.

The exact same thing happens with storm surge -- just on a much larger level.

Storm surge can cover landmasses with several feet of water. Early indications are parts of barrier islands in Southwest Florida saw between 8-15 feet of surge.

The surge is also dangerous because it is moving water.

This water has unbelievable power, which can rip trees from the ground and even lift homes.

Storm surge hits in two ways -- incoming surge and outgoing surge.

The surge rapidly increases as the hurricane approaches an area. This is the incoming storm surge.

Once the hurricane lifts away from an area, winds quickly shift and the surge rapidly retreats out to the sea. This is outgoing storm surge.

This outgoing surge can take huge objects, like boats and homes, and displace them miles away. It can even deposit them into the bottom of the sea.

This is why in parts of Fort Myers Beach, the debris from homes is missing -- it’s likely sitting at the bottom of the Gulf.

Why was the surge so bad with Ian?

Ian was the worst-case scenario for storm surge in Southwest Florida.

Storm surge is a product of the approach of a storm, the depth of the sea, and the geography of the area.

Ian’s track was almost the worst-case scenario for Southwest Florida.

Storm surge is also the worst on the right-front quadrant of the storm.

This is the quadrant that crossed over Southwest Florida as Ian made landfall.

The right-front quadrant allows strong winds to pile up water ahead of and during landfall. This makes the storm surge very large and will often overflow onto land.

Southwest Florida is highly susceptible to surge due to the shallow Gulf of Mexico off the Southwest Florida coast. A much deeper body of water, like the Atlantic Ocean, can absorb some of the storm surge as it approaches land.

Unfortunately for Southwest Florida, water displaced by the storm has nowhere to go but inland.

Likely the biggest reason for the extreme surge is the geography of the area.

Southwest Florida is remarkably flat, with a minimal increase in elevation. This allows the surge to plow into inland areas.

The area also has a significant river in the Caloosahatchee. The surge was able to push up the river and flood out much of Downtown Fort Myers. The downtown area is about 15 miles inland from the Gulf.

Can it happen here?

Possible storm surge in the Jacksonville area from a Cat 1 storm

Storm surge can happen anywhere along a body of water that is prone to tropical systems, including in our region.

Northeast Florida and Southeast Georgia do have some advantages to mitigate storm surge.

Being on the Atlantic, the water off our coast is significantly deeper than the Gulf side of Southwest Florida. This deeper water allows the Atlantic to partially absorb the incoming storm surge.

Another advantage is our terrain.

While Northeast Florida and Southeast Georgia are relatively flat, there are some minor elevation increases that will protect the higher ground from storm surge.

Unfortunately, like Southwest Florida, we also have a large river in the St. Johns, which storm surge would almost certainly be able to push into.

This would create significant flooding along the river and in some of the area tributaries. This has happened in the past with previous hurricanes.

You can learn more about storm surge and its impacts on your community on this interactive National Hurricane Center website: https://experience.arcgis.com/experience/203f772571cb48b1b8b50fdcc3272e2c

We will talk more about Ian’s impact and why the storm was so bad in the coming days and weeks.


About the Author:

David Heckard is The Weather Authority's Assistant Chief Meteorologist.