Shallow water means high storm surge from Helene

NASHVILLE, Tenn. (WKRN) — The storm surge forecast for the Big Bend area of Florida is for up to 20 feet of water that would push inland out of the Gulf of Mexico. That would come from what is expected to be Category 4 Hurricane Helene.

As the storm comes ashore south of Tallahassee on Thursday evening, southwest winds of 130 miles per hour, with gusts up to 160 miles per hour, are expected to push directly ashore around the south side.

However, there is another factor at play in the high storm surge: a shallow water coastal shelf.

When shallow water extends far out to sea, the storm surge is allowed to push more easily towards the land, with the water having nowhere else to go but inland.

If the water is deep just offshore, it has more places to go than straight inland. Some of the water could even “tuck underneath” and return back out to sea below the surface.

This would result in a lower storm surge (though still life-threatening) than along a shallow-water coastline. Many Middle Tennesseans have visited those areas and have seen that deep blue water color just about 100 yards or so offshore, where the depth drops off 30 to 50 feet very quickly.

The Big Bend area of Florida and most of the west coast of Florida has shallow water extending far offshore. Though still dangerous, the storm surge along the beaches there would be lower than a shallow water coastline.

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