storm surge heights

[nyc_bob]

Statement as of 12:57 PM EDT on October 30, 2012

... Maximum water levels from Post-tropical cyclone Sandy and
accompanying surge...

United States geological survey gauges

... ... ... ... ... ... ... ... ..maximum... ... .astronomical... .storm
location... ... ... ... ... .water level... ... tide level... ..Surge... ..Time
Freeport... ... ... ... ... .10.12 ft ngvd... 2.27 ft ngvd... .7.85 ft... 930 PM
Reynolds Channel... ... ..10.10 ft ngvd... 2.32 ft ngvd... .7.78 ft... 906 PM
Lindenhurst... ... ... ... ..7.73 ft ngvd... 1.47 ft ngvd... .6.26 ft..1006 PM
East Rockaway... ... ... ..10.80 ft ngvd... 2.72 ft ngvd... .8.08 ft... 842 PM
Jamaica... ... ... ... ... ..11.65 ft ngvd... 3.28 ft ngvd... .8.37 ft... 936 PM
Rockaway... ... ... ... ... .11.75 ft ngvd... 2.81 ft ngvd... .8.94 ft... 924 PM

National ocean service gauges

... ... ... ... ... ... ... ... ..maximum... ... .astronomical... .storm
location... ... ... ... ... .water level... ... tide level... ..Surge... ..Time
Bergen Point... ... ... ... 14.60 ft MLLW... 5.15 ft MLLW... .9.45 ft... 924 PM
battery... ... ... ... ... ..13.88 ft MLLW... 4.65 ft MLLW... .9.23 ft... 924 PM
Kings Point... ... ... ... .14.38 ft MLLW... 5.60 ft MLLW... .8.78 ft..1000 PM
Bridgeport... ... ... ... ..13.26 ft MLLW... 5.31 ft MLLW... .7.95 ft..1006 PM
New Haven... ... ... ... ... 12.30 ft MLLW... 3.97 ft MLLW... .8.33 ft... 930 PM
New London... ... ... ... ... 8.04 ft MLLW... 2.08 ft MLLW... .5.96 ft... 812 PM
Montauk... ... ... ... ... ... 7.12 ft MLLW... 1.88 ft MLLW... .5.24 ft... 812 PM

ngvd = National geodetic vertical datum of 1929

MLLW = mean lower low water

Storm surge is defined as the abnormal rise of water generated by
a storm... over and above the predicted astronomical tide. The
maximum water level... or storm tide... is the sum of the
astronomical tide level and storm surge.

For the purposes of the tables above... the maximum water level
was the highest water level recorded at the designated gauge. The
astronomical tide level was the predicted tide level for the time
that the maximum water level was measured. The storm surge was
calculated by subtracting the astronomical tide level from the
maximum water level.

 

[Unknown]

I have to ask something - did they pull a fast one on us somewhere? Before the storm the predicted storm surges were 4-8 feet and they seem to have been fairly close on that estimate, but during the storm we started hearing about 10,12, 13, 14 foot heights, am I the only one who thought they were talking about storm surges with THOSE numbers??? Not to sound cynical, but the storm was bad enough without the news media telling us we were having 14 foot storm surges. By comparison, we talk about Hurricane Katrina's 27.8 foot surge and I sure thought the other night that NYC was seeing something way out of the expected realm.

Now this may seem like semantics, after all this storm was horrific. But what is important is to know the facts of how high the water rose. If, for example, we actually got a 14 foot storm surge at Kings Point or the Battery, can you imagine how much worse this storm would have been even then???? This is a really scary thought, indeed!!!

Plus based on those numbers I dont think the actual storm surge was that far out of line for a Cat 1 hurricane. Its just the location that was bad. For example, hurricanes along LI's southern shore have brought 3-5' surges there before. We've just never had one that big in Manhattan or the Bronx.

What I cant figure out, though, is what happened to my friend's uncle's house in Merrick. Out there he had never seen water anywhere near his house in many a hurricane. This one flooded his first floor halfway to the ceiling. Clearly the stars (or at least the moon) were aligned to combine the astronomical tide, size and duration of the surge into a very unusual event, turning a strong Cat 1 hurricane into a Katrina-esque disaster.

All armchair quarterbacking now, but interesting....