You’ll be handed a set of water wings and tossed off the boat fifty yards from shore. Mike Finkbeiner sends along this view of the newly-rearranged pier:
All ashore that are going ashore! Island Beach, Greenwich
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EarthImage – Prediction was between 11.5 and 17.5 above MLLW.
What did OG actually get this storm?
OG- Thanks for the question. We will provide a detailed discussion at
http://earthimage.wordpress.com/ but in the meantime, consider the Stamford Hurricane Barrier discussion at
Ryan’s source at the Army Corps Stamford Barrier, which was built in 1969 after the storms of the 1950′s, states the maximum surge came at low tide, with high water topping out at the old “Mean Sea Level 1929″ value of 11.0 feet. In the modern system used by FEMA for flood insurance, this equates to 9.9 feet (NAVD-1988). I performed a flood damage survey yesterday in a boat pile-up near the American Yacht Club in Rye, where the debris line on the ground – the so-called wrack line but in this case the wreck line- had a ground elevation of 10.1 ft in the FEMA/City of Rye system.
The lowest level of flood hazard is elevation 12 in the FEMA system in terms of flood insurance map ratings. Cos Cob Harbor has a 1% annual risk rating of 12.2 ft. So the official answer is that flood waters peaked 2.3 ft below (12.2 minus 9.9) the rated 100 year hazard ( called the 1% annual risk).
Further, winds in Greenwich peaked at gusts of 72 miles per hour, so like Irene in Greenwich, we have not experienced a hurricane in at least a quarter century.
Thanks, Mike. That’s an impressive recap on Ryan’s blog and the water level chart w/his narrative clarifies a tricky subject.
“We need to make sure we are prepared for the “big one” because Sandy wasn’t it. In fact it wasn’t even close . . . “
Shorelands Association had a high tide measured on the Shorelands “stick” as the Greenwich police call it of 14.0 feet. This was measured by taking high water marks off several of the houses in Shorelands and transferring that reading to the tide measuring gauge attached to one of the pilings at the Shorelands dock. This is the highest reading in the last 25 years, but probably not as high as the 1938 hurricane. Sandy was forecast to produce a 16 foot tide by NOAA at one time, if that had happened, almost every house in Shorelands would have had some damage.
I have not recently calibrated the Shorelands tide stick, but my recollection is that it has zero set to low tide, with the perimeter dike/berm set at 10 in the same system as Stamford. My ratings for the Halloween ’91 “perfect storm” was 9.9 at Shorelands in NGVD, but the December 1992 nor’easter that topped the dike was 10.6 ft and rated by the Town of Greenwich as a 40-year tidal flood event (per Bob Kendra, PE, Town Engineer.) The Stamford reading of 11.0 would have been the highest reading in the last 25 years. and converts to 14.3 in the low tide system, confirming your stick reading.
Pulled Up, Earth and Jack, Thanks for this information and the link to Ryan. All very intelligent, informative and helpful.
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