Help me understand this Storm Surge map

It's probably for a storm going right up the Mississippi. The surge gets funnelled into the river. Only thing that makes sense.

If the River Levees would have failed in New Orleans, the Mississippi would still be running through the city today. No stopping that amount of water flow

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the River Levees would have failed in New Orleans, the Mississippi would still be running through the city today. No stopping that amount of water flow

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If the levees failed further upstream however, the course of the river changes entirely (e.g. Old River Control).

that is utter bullshite

it says a 3 will engulf LC in 9 feet of surge through i10

Rita was a strong 3 and didn't leave that sort of damage. the surge may have made its way to SLC, but nowhere near i10

Yeah this map is fear mongering

I think you're right to think it's wrong, it is. The description seems totally inaccurate IMFO, as if they found the LIDAR but didn't know what it was.

Surge really doesn't travel upriver farther than roughly Nola...BUT...the river does rise in places as far upriver as BR because when the Gulf is elevated due to surge, the water coming from upriver has nowhere to go and piles up on itself. Carrollton gage has risen by ~14' in 24 hours during a storm.

-nerd alert-
Secondly, none of these maps reflect a single storm on a single track. They all employ the same basic idea: there is a relatively small historical record of hurricanes. So, a large amount of "synthetic" storms that are representative of the range of possible intensities and tracks are run
In computers. Then statistical analysis with fancy names such as Monte Carlo Analysis is performed where the distribution of affects across all storms at all locations is binned into what we would all call a 100 year storm, etc.

Another way to describe all that noise is this: you have a pair of dice. The historical record of dice rolls is only comprised of a few rolls, therefore, you really can't compute an accurate probability of roll results with that record. You then build a computer model to simulate hundreds and hundreds of rolls to build a synthetic set of results in a short time so you can then accurately assign probabilities to roll results.

Any one pixel on these maps represents a given probability of a certain set of results over a large sample of simulated events.
-end nerd alert-

Agreed but I am trying to dumb it down.

Note that a category 3 hurricane you mention could actually be pushing a category 5 storm surge, as the case with Katrina, because the categories are determined by continuous WIND speed at the time of LANDFALL rather than any measure of the water. In Katrina's case I believe at landfall it clocked sustained 127 mph (with gusts much higher), which gave it only a cat 3 designation. However, it was a HUGE storm with an eye which alone was 38 miles in diameter and which earlier was clocking sustained 175 mph and pushing a cat 5 storm surge. Where the eye struck in Plaquemines Parish the surge was measured at 30.4 feet deep, with wave action on top of that. Eyewitness accounts place water well over the tops of the backboards of the high school gymnasium.

Also I would imagine that the maps of projected water levels to which you refer may show the level any given location COULD receive should that particular location get the maximum possible hit, and NOT the levels which ALL locations would suffer.

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It's probably for a storm going right up the Mississippi. The surge gets funnelled into the river. Only thing that makes sense.

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nope, that doesn't make sense. That wouldn't happen.