Read his words below....especially the quote that, "the sudden rise of 4 feet brought it [the water] above my waist before I could change my position."
Quote from Isaac Cline:
The water rose at a steady rate from 3 p.m. until about 7:30 p.m., when there was a sudden rise of about four feet in as many seconds. I was standing at my front door, which was partly open, watching the water, which was flowing with great rapidity from east to west. The water at this time was about eight inches deep in my residence, and the sudden rise of 4 feet brought it above my waist before I could change my position.
Story source: http://www.history.noaa.gov/stories_tales/cline2.html
Bringing this back to Hurricane Sandy:
Winds right now are generally blowing from the northeast across much of coastal NJ and NY. This is driving water down Long Island Sound from east to west, causing the highest surge levels (according to NOAA Tides and Currents) of more than eight feet at King's Point (on extreme SW Long Island Sound.) Surge levels at Battery Park are between 6.5 and 7 feet.
Beware of sudden water level rise in The Battery, NYC area, and south-facing shores of Long Island, this evening. After Sandy makes landfall in NJ, winds will quickly change direction, blowing in from the SE, then S, which may cause rapid water-level rises near NYC. You may not have time to escape the sudden water-level rise.