I just finished reading a thriller called Presidential Deal by Les Standiford, and in it, he has the hero and heroine stranded on one of those tiny nameless Bahamian cays during a hurricane, and he has the hurricane’s storm surge come up over the island like a tsunami, a fast-moving wall of water that sweeps away everything in its path on the island, except for the big blocks of stone in the abandoned quarry where the hero and heroine have taken refuge (as for why there’s an abandoned quarry on a tiny nameless Bahamian cay, I have no idea). And the tiny nameless Bahamian cay was described as being barely 20 feet above sea level, so we’re talking at least a 20 to 30-foot high wave.
Anyway…
My understanding has always been that the storm surge is just a fast-moving tidal flow of incoming sea water, a “bulge” of water, a really high tide that comes in in a really big hurry, not that it’s a tsunami-like devastating “wave” that sweeps things away.
Anybody out there ever actually witnessed a storm surge?
I have. I grew up in South Florida and went thru umpty-ump hurricanes. You are correct, a hurricane storm surge is a significant increase in the tidal swells, and can cause flooding inland, but is NOT like a tsunami.
Remember the lessons of Christmas 2004: A tsunami doesn’t always look like a tsunami.
Not 100 percent on the terms, but I think the surge more closely approximates a tidal “bore.” IOW, there’s a gradual rise in the entire sea–sometimes up to 30 feet–with fairly big waves sometimes riding atop this elevated sea level.
Yeah. The storm surge related to a hurricane is nothing like that. As a hurricane moves across the ocean, its winds and pressure effects act to build up an area of sea water that is higher than mean sea level. It’s basically a hill in the ocean that moves at roughly the same speed as the hurricane, AFAIK. As the hurricane approaches land, it carries this hill along with it onto land. Hurricanes move fairly slowly, and the buildup of the water along the coast is (relatively) gradual, so it’s nothing that you would have to run from, and certainly nothing like in that story.
BTW, last year when (then-)TS Frances blew through here, she brought a storm surge with her. You can see the results here, in this gallery. You can see from the photographs that this was gradual, because the rising sea did not damage the trees and bushes. The only damage to the buildings was from the flooding, not any sort of violent wave activity. What happened here is that the storm pushed the water from Tampa Bay up into the Hillsborough River, which flows through downtown Tampa before emptying into the bay itself. The water level in the bay was higher than that of the river, so the river was basically dammed by the storm surge and rose over its banks, adding even more water to the 4 - 8 ft surge which Frances was bringing ashore. In addition, you can see in some of the pictures that there are waves washing over the bridges – that’s because the wave activity on top of this hill of water stays basically the same as it does on a normal sea. The waves are just forming higher than usual.
The night before was really something. Thanks to the winds and the shape of the bay in certain areas, you could see the seafloor for about 100 yards out along Bayshore Blvd, which is built along a sea wall. Ordinarily, there’s really no beach there at all, much less one 300 ft wide. But again, that was a gradual recess of the waters and a gradual return overnight and into the next day.
Oh, and from my understanding of tidal bores, it’s not really anything like that either, at least around here. All the pictures of tidal bores I could find showed a little water wall moving up a river. It’s not even like a wall at all. It’s more like a tide that just keeps coming in.
How did he see anything through the tons of rain in the air, much less the wave caps that were being blown around by the wind? Visibility in the one hurricane that I weathered was at one quarter mile or less (admittedly, I was miles inland.)
A storm surge is made of water piled up by the winds that blow towards the low pressure of the eye. It has a gradual slope, not the steep face of a breaker or rogue wave. Of course, there will be a lot of heavy seas atop the storm tide.
Also, a storm surge of 30 feet would be the result of an off-the-chart category 5 hurricane. Category 5s start at winds of 155 mph and storm surge greater than 18 feet. In a storm with a 30 foot surge, the water would be among your final concerns. The greatest immediate concern would be the 200 mph winds turning everything outside into a deadly missile.
Yes, and I have pictures. If you didn’t know the regular water level in the area, you’d not even notice that it’s happening until it starts lapping at the coastal roadbeds. It’s not a wave; it’s more like a tidal inflow.
