Storm Surge-How far inland can it go?

[cajungal]

I got a question. If a major hurricane, was to hit here this season, like a 4 or 5, how far inland would the surge get? Because I read that the surge from a 5, would travel as far inland as Napeoleonville. To me that seems kind of extreme because Napeoleonville is about 70 miles from the coast at least. I live about maybe 30 miles inland depending on what direction you are coming from. Anyone familiar with the Houma-Thibodaux area? Do you think the surge could ever make it this far?

[Brent]

It could if it's flat enough... although I don't think 70 miles. If it's a 5, I think 30 miles would be reasonable. Remember: where you live is swampy. There are no beaches and high rises on the water there(well, unless you count New Orleans).

BTW: If a 4 or 5 ever hits New Orleans, the city would go completely underwater. It'd be a combination of surge and flooding(from the Lake on one side and the Gulf on the other).

[SouthernWx]

I'm not sure if the storm surge would reach Napoleonville.....but if a large cat-4/5 slams into southern Lousiana, the storm surge will go a long way inland.....because of 1) shallow slope of the Gulf offshore and 2) southern Louisiana is so low lying.

During severe hurricane Audrey in 1957, the storm surge reportedly reached over 25 miles inland in places from the open gulf.

The worst case scenario for most of southern Louisiana is a powerful hurricane moving due north (similar to Audrey).....but for greater New Orleans, even worse would be either 1) a violent hurricane track just east of the city (with Lake Ponchartrain in the western eyewall and northerly winds of 130+ mph) OR 2) a severe hurricane moving WNW and passing just south of New Orleans (bringing all that shallow water from Breton Sound/ offshore the Mississippi coast westward into overflowing Lake Ponchartrain). Either scenario would likely mean catastrophic flooding in the city of New Orleans.

PW

[Agua]

http://www.storm2k.org/phpbb2/viewtopic.php?t=62806

Try the storm surge / evac zone mapping tool linked in the above post.

Click on the state you're interested in, and enter search parameters.

[skywarn]

I think Napeoleonville may escape the brunt of a storm surge from a Cat 4 or 5 however on a critical path a Cat 4 or 5 would bring water as far as the Houma area through the canals ,basins , wetlands,etc. There was some flooding in the areas surrounding Houma from Georges in 98, and Isidore & Lili in 2002.With the loss of the barrier islands even a Cat 1 could wreak some havoc now. Click on the below link and watch the Quicktime movie to see what would happen to New Orleans from a Cat 4 on a critcal path from the southeast.You'll find it interesting to say the least.

http://www.nhc.noaa.gov/HAW2/english/su ... eans.shtml

There below link shows a map of the storm surge from a slow moving Cat 3 from the south.

http://www.publichealth.hurricane.lsu.e ... 0Flood.htm

[Scorpion]

Im a little skeptical of surges going so far inland. During Frances and Jeanne we got nothing from the ocean here. I highly doubt a 10 foot wall of water is going to come crashing 3 miles inland where I live.

[SouthernWx]

Im a little skeptical of surges going so far inland. During Frances and Jeanne we got nothing from the ocean here. I highly doubt a 10 foot wall of water is going to come crashing 3 miles inland where I live.

It's a very different scenario along the Florida east coast south of Melbourne (as compared to most of the Gulf Coast)....where Atlantic waters are very deep just offshore, reducing the size of storm surge, even in powerful hurricanes.

Even the intense September 1947 category 4 hurricane (940 mb/ 120 kt) only produced a 11-12' storm surge in Broward and Palm Beach counties. While this caused severe storm surge damage along the immediate shoreline (and barrier islands), the surge didn't reach very far inland. However, this was an extremely large and slow moving hurricane, and severe flooding resulted across much of peninsular Florida from excessive rainfall amounts....reaching 30-40" in some areas over a three day period.

[LSU2001]

Check out run 2 animation. If it shows what I think it shows it might not be too far out to think that Thibodaux could see flooding from a major storm.
Tim
http://hurricane.lsu.edu/floodprediction/isidore/

[Derek Ortt]

unless you have a cat 5 for the FL peninsula, you're not getting a surge. E FL's surve values are closer to what is expected at Cayman due to the deep water (though higher since the water is not quite as deep_ than the rest of the USA

[BayouVenteux]

An animated storm surge simulation done a couple of years ago of what could possibly occur in terms of flooding in southeast Louisiana if a storm identical to Betsy's path and intensity were to make landfall.


Small format (fast load)
http://www.nola.com/hurricane/popup/bet ... model.html

Large format (slower loading)
http://www.nola.com/hurricane/popup/bet ... model.html

[SouthernWx]

unless you have a cat 5 for the FL peninsula, you're not getting a surge. E FL's surve values are closer to what is expected at Cayman due to the deep water (though higher since the water is not quite as deep_ than the rest of the USA

Well, while true you won't experience extreme tides (15'+) along the southeast Florida coast from a cat-4.....I wouldn't say they aren't getting a surge Derek.

The Great Miami hurricane in 1926 was a strong cat-4....and the 11-13' storm surge innundated Miami Beach and downtown Miami. With such a low lying area (<10'), the immediate (and densely populated) shoreline areas and barrier islands are of great concern to hurricane preparedness experts. If another 935 mb hurricane slams inland with Miami, Miami Beach, and Key Biscayne inside the northern eyewall, and folks have not evacuated, IMO many will die....most from drowning

We were somewhat fortunate with Andrew in 92', because the area of max storm surge was south of highly populated beachfront/ barrier island areas. I remember the far south end of Key Biscayne was obliterated.....if Andrew were only 15 miles farther north (or slightly larger), we would have IMO witnessed a catastrophe, with hundreds who didn't evacuate from Miami Beach being drowned (and Dr Sheets has said the same).

PW

[mitchell]

I got a question. If a major hurricane, was to hit here this season, like a 4 or 5, how far inland would the surge get? Because I read that the surge from a 5, would travel as far inland as Napeoleonville. To me that seems kind of extreme because Napeoleonville is about 70 miles from the coast at least.

Three observations about surge and why surge maps overestimate inundation.

1) I've always felt that they don't handle overland frictional dissipation very well. Trees, buildings and vegetation are very frictional and I just don't belive they account for the tremendous dissipation that occurs

2) In most parts of the country the inundation area maps are based on USGS topography which is generally only accurate to +/- 5-10 feet. Leads to huge error in flat areas

3) Many surge maps are showing the Maximum Envelope of Water (MEOW) which is showing combines all possible landfalling directions at a given category and then overlays all these maps the extent of flooding from all of the given directions. Most landfalling storms will not be coming from the worst case direction.

[Scorpion]

So I am barely in an evacuation area due to surge flooding, but I don't think I will evacuate if a hurricane comes this way because the surge most likely won't come near me. I also think that the surge maps have errors.

[LSU2001]

Cajungal,

I think that the flooding would travel far inland, however the true devastataing surge would be confined to those areas closest to the gulf and exterior bays and marshes. The water would surely rise as far north as Lower Livingston, Assumption,St. Mary's, etc. but I doubt that it could cause trememdous destruction. The rainfall from such a system however could. With allison there was no storm surge but flooding from rain was a huge problem on the Amite, Comite, Tickfaw, Tangipohoa, rivers and it also flooded areas south of plaquemine like Bayou Pigeon, Bell River etc. Also water being pushed around the Hurricane Protection Levees would make the surge travel farther inland but I really do not think that the levels would be high enough for serious problems.
Tim

THis is only my opinion and represents the ideas of a true amature. Donot take this as any type of reliable forecast.

[skysummit]

Hmmm...I think Schriever would be a questionable call and we'll only know if it happens. I'm extremely familiar with the area. There's a lot of swampy area along LA 20 toward Donner and Gibson, and those swampy areas have a direct feed from the Intercoastal and Gulf inlets so if a storm were to hit the right area at the right speed, Schriever may see a little storm surge.

Something else we need to worry about are our levees. If a slow moving CAT 3 or stronger would hit near Houma/Morgan City...kinda like Andrew did, but slower, we would probably see major flooding. The flooding would come from our levees breaking. The constant beating and pressure of water from the south would eat away those levees rather quickly. I know even when a slow moving TS hits, I always here reports of the chance of a levee breaking. Remember Juan? Barely a hurricane, but it's wierd track and very slow movement put 4 feet of water in my home simply because a levee broke.

South La., is so different than any other place along the coast. You can be 50 miles inland and still barely above sea level. I heard a report a couple weeks ago on 870AM that said if a slow moving CAT3 would hit just west of New Orleans and travel from the SE to NW, that would pour 14-18 feet of water inside the city and that water would stay there for 6 - 8 months! That's unthinkable, but very likely to happen one day. New Orleans' main problem is once the water is there, how do we get it out?

[vbhoutex]

So I am barely in an evacuation area due to surge flooding, but I don't think I will evacuate if a hurricane comes this way because the surge most likely won't come near me. I also think that the surge maps have errors.

Pure fallacy of thought. How do you know they have errors? It is classic "it won't happen to me" thinking. If you even have a chance of the surge getting to where you are you should leave!! I know you are young and find Hurricanes exciting, but don't let the adrenalin rush of the storm and its power cloud your thinking.
Unless you can prove those "errors", which I'm sure the officials would like to know about, I would follow the maps and the officials orders in the event of a Hurricane.

[mitchell]

Unless you can prove those "errors", which I'm sure the officials would like to know about, I would follow the maps and the officials orders in the event of a Hurricane.

Good advice. There are a whole bunch of good reasons to follow evacuation orders that have nothing to do with surge inundation at your precise location. I wouldn't call them errors - which implies a mistake was made - any sort of hazard mapping is only as good as the data that was used to create the maps. Cones of uncertaintainty in forecasts tracks don't equate to error as much as an admission that the data doesn't not support a more precise prediction. Surge maps have a "bright line" at the limit of the inundation area instead of a cone of uncertainty...

[cajungal]

You see my mom panicks everytime a storm seems to be coming this way. I kept telling her that yeah, we will get the hurricane force winds of 100 mph or more. But, I doubt if we will ever get the surge. Officials said that for a 3 or greater, the surge would reach all the way to Houma. That is only 9 miles to my north. Houma and Schriever are both swampy areas. And nothing but marshy areas right below Houma. With Lili, Isidore, and Bill, directly south of Houma was under 4 ft of water, even 8 ft in some places. I live in a brick home. And I am guessing my yard is at least 8 ft above sea level. We never once flooded ever. While my neighbors all flooded, we we were one of the few ones left high and dry. My mom wants to evacuate for every storm now. But, we still never actually left before. They say we are at least 20 miles closer to the Gulf now than we were for Andrew in 1992.

[gtalum]

Three observations about surge and why surge maps overestimate inundation.

All of that makes sense. of course they want to give the worst possible scenario on those maps, to avoid people on the fringes stayign home when there's an outside chance they could flood.

[SouthernWx]

A couple of quick points:

1) landfalling U.S. cat-4 or 5 hurricanes are fairly rare occurrences, especially since the U.S. coast became a popular spot to live (around 1970). This means many of those hurricane storm surge maps are UNTESTED in a real violent hurricane. I was honestly surprised the storm surge from Charley last August was much lower than anticipated for such an intense (941 mb) hurricane in that area of SW Florida. [b]On the other hand, BOTH hurricane Hugo (934 mb) and Andrew (922 mb) produced HIGHER storm surges than believed would occur for their respective landfall areas.

We were very fortunate that neither Hugo nor Andrew's storm surge caused mass loss of life....but that was only because Hugo's highest storm surge occurred in sparsely populated marshland northeast of Charleston AND Andrew's max storm surge occurred over a very narrow corridor south of Miami Beach and other populated barrier islands/ beachfront areas.
If Hugo had slammed inland just southwest of Charleston, IMO hundreds would have drowned; if Andrew had made a direct hit on Miami Beach, the toll in lives IMO would have exceeded 1000.

If I lived on a barrier island or along the immediate coast...particularly in an area which hasn't experienced a cat-4/5 hurricane in recent decades, I wouldn't risk my life or the lives of my family based on storm surge maps which haven't "battle tested" during an actual severe hurricane....if I was even close to an evacuation zone and a cat-4 or 5 hurricane was approaching, I'd get the hell out....would take no chances.

2) I wish every single person living on a barrier island or immediate shoreline area could sit and listen to my distant cousin Gary's wife describe her harrowing account of hurricane Camille near Gulfport, Mississippi. Julie was only 8 years old at the time, but says she still has nightmares about that horrible night (as the water rose, her father cut a hole in the ceiling and roof, trying frantically to keep them all above the water level). Sadly, she lost her mom that evening (drowned)....and they lived five blocks inland from the beach

PW