Re: NHC Releases National Map of Storm Surge Risk
Posted by
Chris in Tampa on 11/11/2014, 9:32 pm
It is somewhat confusing though because when you click on a wind category it makes you think that is the maximum water level you could see with the worst storm for that particular category. But I think the estimates are low when it comes to storms like post-tropical Sandy and hurricane Ike. (Sandy in places had about 10 to 13 feet I think above sea level at the coast.)
The scale says this though:
Up to 3 feet above ground
Greater than 3 feet above ground
Greater than 6 feet above ground
Greater than 9 feet above ground
So when it says "Greater than 3 feet above ground" it doesn't mean it can't be 10 feet at that location above ground. That is kind of misleading.
I think the map doesn't let you zoom in close with the overlay because it is simply not that detailed. The SLOSH model doesn't get that detailed, so if you zoomed in to a particular neighborhood, it simply is not detailed enough to tell you what will flood and what will not. If it allowed you to zoom in people might make the assumption that the map really is that accurate to that level. Between my neighborhood and the one next to me, there is actually a lot of elevation difference, well, several feet, but it is enough to matter greatly when it comes to insurance, but I don't think the model has anywhere near that kind of resolution.
The NHC does have the storm specific version too. In fact, now that I looked at that again, which I had forgot because it didn't have much chance to be used this season, this is something that should be covered on that national map:
"What the Map Represents
The experimental Potential Storm Surge Flooding Map represents the storm surge heights that a person should prepare for before a storm, given the uncertainties in the forecast. The map shows a reasonable estimate of worst case scenario flooding of normally dry land at particular locations due to storm surge. There is a 1-in-10 chance that the storm surge flooding at any particular location could be higher than the values shown on the map."
From:
http://www.nhc.noaa.gov/experimental/inundation/
That makes all the difference in the world. I assume then that the national map uses that same rational. They need to be more clear about that. The SLOSH page they link to does link to that page, but it should actually be more clear if that is what that map represents. (Has a 10% chance of exceeding those values, which would cover unusual storms like Sandy and Ike.) |
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