Simon Young walks almost knee-high in the water flooding his...

Simon Young walks almost knee-high in the water flooding his home and backyard on Willow Street in Babylon Village. (Oct. 29, 2012) Credit: James Carbone

Sandy tossed water over seawalls in calamitous fashion as its torrential bands reached land. Yet another twist of nature helped set floods in motion to wash away roads and damage homes -- storm surges of 10 feet or more fed by the timing of high tides, low pressure of the storm and a full moon.

Those storm surges can inundate historically flood-prone areas on both the North and South shores, the National Weather Service said.

Forecaster David Stark said that winds from the storm not only cause water to "pile up" in inlets and bays, but they will keep the floodwaters from receding to normal low-tide levels. Then, as winds change direction, the water is set free to pour into inlets, bays -- and Long Island Sound.

Waves pouring atop the storm surge were especially damaging on South Shore beaches, where 20-foot breakers were seen roaring ashore.

"The destructive waves on top of the storm surge will cause overwashes and significant damage to coastal structures nearest to sea level," the weather service said.