Storm Surge/ Wave Height Question

jd10135 · 08-31-2008, 07:48 PM

Sea level is at elevation 0. At normal high tide maybe its at about elevation +1. At low tide, maybe its at about elevation -1. Storm surge in Destin is predicted to be 3 feet. I take it that this means it will rise to 3 feet above normal high and low tides. So if it hits at low tide, the sea level will rise to about elevation +2. If it hits at high tide, the sea level will rise to about elevation +4. Is this true?

Simultaneous to the storm surge of 3 feet, I read that seas will be 25 feet.

Does this mean that, where the depth to the bottom of the seafloor is deep enough to accomodate the 25 foot waves without themcollapsing ont themselves, the peak of the waves will rise to elevation 12.5 and that the nadir of the waves will be at elevation-12.5?

What will keep the 25 foot waves from hitting the shore and creating a surge much higher than the predicted 3 feet, and how do you translate the surge into an actual elevation.

Why I ask: A friend owns a condo on Holiday Isle, whose parking level is at elevation +7. The marine forecast calls for 25 foot seas in the "near coastal" waters. The predicted storm surge is 3 feet. Assuming the seas do in fact get to 25 feet, and the storm surge is in fact 3 feet, will the parking level at elevation +7 remain dry?

Thanks fellow nerds...

weatherman · 08-31-2008, 08:31 PM

http://www.nhc.noaa.gov/psurgegraphics_at2.shtml

I dont think you have anything to worry about.

jd10135 · 08-31-2008, 08:36 PM

I'm not worried, I just wonder how all the math works out.

weatherman · 08-31-2008, 08:45 PM

Well, you are sort of comparing apples to oranges. Storm surge and wave heights are two different animals. Waves break at the beach, storm surge doesnt. Storm surge adds more water for the waves to break on if you will. Waves eat at the beach where storm surge goes over the beach. A 25 footer will still break at the beach, albeit I dont want to be standing there when it does, at least here anyway. Just look at Hawaii, they have monster waves everyday. Good conversation piece though, especially over a few frosties....

Pier#r · 08-31-2008, 09:12 PM

I believe your question is quite valid. If for no other reason, as sea level rises (either with the tide or to a much larger extent the storm surge) taller waves can break closer to the beach as the water is then deeper over the offshore bar where waves would ordinarily expend most of their energy (break).

Eventually the water piled up by training waves (sets) can push farther up the beachand overwash the dunes. This is a more localized phenomenon that can exceed the general storm surge heights. Still it is unlikely to occur except when accompanied by incoming astronomical tides ofenough magnitude to aid the water in moving up onto the coast.

For this storm in Destin most of the storm surge will come from the large swells and onshore winds piling and holding more water against the shore. Likelythe cummulativeeffects will still not be near enough to flood the shoreside homes built to codes. Maybe some parking lots and stuff like that.

Hope this helps and all are safe!

Maps · 09-01-2008, 10:05 AM

The surge has been getting deeper the past 3 hours. I'm on Hoffman bayou (north side of gulf Breeze). The water was just under the deck boards @ 0600 and now it's over the top.

weatherman · 09-01-2008, 10:16 AM

Any crabs in that trap?

08-31-2008, 07:48 PM	#1
jd10135 Junior Member Cigar Minnow Join Date: Nov 2007 Posts: 9	Storm Surge/ Wave Height Question Sea level is at elevation 0. At normal high tide maybe its at about elevation +1. At low tide, maybe its at about elevation -1. Storm surge in Destin is predicted to be 3 feet. I take it that this means it will rise to 3 feet above normal high and low tides. So if it hits at low tide, the sea level will rise to about elevation +2. If it hits at high tide, the sea level will rise to about elevation +4. Is this true? Simultaneous to the storm surge of 3 feet, I read that seas will be 25 feet. Does this mean that, where the depth to the bottom of the seafloor is deep enough to accomodate the 25 foot waves without themcollapsing ont themselves, the peak of the waves will rise to elevation 12.5 and that the nadir of the waves will be at elevation-12.5? What will keep the 25 foot waves from hitting the shore and creating a surge much higher than the predicted 3 feet, and how do you translate the surge into an actual elevation. Why I ask: A friend owns a condo on Holiday Isle, whose parking level is at elevation +7. The marine forecast calls for 25 foot seas in the "near coastal" waters. The predicted storm surge is 3 feet. Assuming the seas do in fact get to 25 feet, and the storm surge is in fact 3 feet, will the parking level at elevation +7 remain dry? Thanks fellow nerds...

08-31-2008, 08:31 PM	#2
weatherman Senior Member Grouper Join Date: Oct 2007 Posts: 915	RE: Storm Surge/ Wave Height Question http://www.nhc.noaa.gov/psurgegraphics_at2.shtml I dont think you have anything to worry about. __________________ Owner, Gulf Coast Outfitters, LLC Duck/Turkey/Hog Hunting Guide Services Pistol/Carbine Instruction Survival Instruction Tactical/Hunting Gear http://www.gcoonline.com/ Like us on Facebook http://www.facebook.com/GulfCoastOutfitters http://twitter.com/GCOonline

08-31-2008, 08:36 PM	#3
jd10135 Junior Member Cigar Minnow Join Date: Nov 2007 Posts: 9	RE: Storm Surge/ Wave Height Question I'm not worried, I just wonder how all the math works out.

08-31-2008, 08:45 PM	#4
weatherman Senior Member Grouper Join Date: Oct 2007 Posts: 915	RE: Storm Surge/ Wave Height Question Well, you are sort of comparing apples to oranges. Storm surge and wave heights are two different animals. Waves break at the beach, storm surge doesnt. Storm surge adds more water for the waves to break on if you will. Waves eat at the beach where storm surge goes over the beach. A 25 footer will still break at the beach, albeit I dont want to be standing there when it does, at least here anyway. Just look at Hawaii, they have monster waves everyday. Good conversation piece though, especially over a few frosties.... __________________ Owner, Gulf Coast Outfitters, LLC Duck/Turkey/Hog Hunting Guide Services Pistol/Carbine Instruction Survival Instruction Tactical/Hunting Gear http://www.gcoonline.com/ Like us on Facebook http://www.facebook.com/GulfCoastOutfitters http://twitter.com/GCOonline

08-31-2008, 09:12 PM	#5
Pier#r Your PERSONAL Shore Guide Snapper Join Date: Oct 2007 Posts: 493	RE: Storm Surge/ Wave Height Question I believe your question is quite valid. If for no other reason, as sea level rises (either with the tide or to a much larger extent the storm surge) taller waves can break closer to the beach as the water is then deeper over the offshore bar where waves would ordinarily expend most of their energy (break). Eventually the water piled up by training waves (sets) can push farther up the beachand overwash the dunes. This is a more localized phenomenon that can exceed the general storm surge heights. Still it is unlikely to occur except when accompanied by incoming astronomical tides ofenough magnitude to aid the water in moving up onto the coast. For this storm in Destin most of the storm surge will come from the large swells and onshore winds piling and holding more water against the shore. Likelythe cummulativeeffects will still not be near enough to flood the shoreside homes built to codes. Maybe some parking lots and stuff like that. Hope this helps and all are safe!

09-01-2008, 10:05 AM	#6
Maps Member Ruby Red Lip Join Date: Apr 2008 Posts: 59	RE: Storm Surge/ Wave Height Question The surge has been getting deeper the past 3 hours. I'm on Hoffman bayou (north side of gulf Breeze). The water was just under the deck boards @ 0600 and now it's over the top.

09-01-2008, 10:16 AM	#7
weatherman Senior Member Grouper Join Date: Oct 2007 Posts: 915	RE: Storm Surge/ Wave Height Question Any crabs in that trap? __________________ Owner, Gulf Coast Outfitters, LLC Duck/Turkey/Hog Hunting Guide Services Pistol/Carbine Instruction Survival Instruction Tactical/Hunting Gear http://www.gcoonline.com/ Like us on Facebook http://www.facebook.com/GulfCoastOutfitters http://twitter.com/GCOonline

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