Unusually high tides were observed in the Hudson River Estuary this week from Albany to the New York Harbor. Employees at the Norrie Point Environmental Center in Staatsburg, NY, observed the water lapping over the edge of their patio. I saw water creeping closer to the Albany-to-Troy riverfront bike trail.
This past weekend's storm battered our coast with winds and rain. Although the rains probably contributed to the high water levels, the primary driver was the storm surge caused by strong northeastern winds.
When coastal winds blow from the northeast, they force water towards the shore. This is because the Coriolis effect causes waters to move 90 degrees to the right of the direction they are forced. In fact, more water is pushed towards the shore by winds from the northeast than by head-on winds from the south east.
Northeastern winds are also associated with low pressure systems. The low pressure pulls the coastal waters upward. Sea levels rise, in this way, like water rising up a drinking straw.
With coastal waters forced to shore and low pressure lifting surface waters, we see a significant rise in water levels during Nor'Easter storms. This rise is referred to as a storm surge.
This weekend's Nor'Easter began on Friday and peaked on Sunday with winds on the river exceeding 14 m/s or 27 knots. The resulting surge in coastal water levels were first seen on Friday, peaked Sunday, and persisted through Wednesday evening. Echoes of the surge could be observed throughout the Hudson River Estuary from the NY Harbor to Albany, NY.
At times, storm surges can cause flooding. This weekend, for example, saw moderate flooding in the NY Harbor and minor flooding at Poughkeepsie. The Stevens Institute has developed a Storm Surge Warning System to alert municipalities of potential flooding in their region. Systems such as this will become even more important as sea levels rise in response to climate change.