A slow moving Nor'easter impacted successive high tide cycles with widespread minor to locally moderate coastal flooding on the evening of 1/23 and widespread moderate to locally major coastal flooding the morning of 1/24.
Thirty six hours of east northeast gale to storm force winds helped build surge values to 3 to 4 feet above astronomical tides for the 1/24 morning high tide cycle. This caused widespread moderate to locally major coastal flooding along the southern and eastern bays and beachfront communities of Long Island. Coastal communities across the rest of the Tri-State area mainly experienced minor impacts.
Coastal flood watches, warnings and advisories were issued and IDSS performed well in advance to warn coastal community residents of the potential impacts.
In addition, widespread beach and dune erosion occurred at Atlantic ocean beaches from elevated waters levels and an east to west sweep of 8 to 12 feet of surf Monday  into Tuesday.

Coastal Flood in NORTHEAST SUFFOLK, NEW YORK
From 24-JAN-17 06:00:00 to 24-JAN-17 10:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

The USGS tidal gauge on the Peconic River at Riverhead recorded a peak water level of 6.6 ft. MLLW at 748 am EST. The moderate coastal flood threshold of 6.1 ft. MLLW was exceeded from 618am to 930am EST. The moderate coastal flooding thresholds were established by the National Weather Service, based on impact analysis and collaboration with the USGS and local emergency management.

Coastal Flood in SOUTHERN NASSAU, NEW YORK
From 23-JAN-17 17:00:00 to 23-JAN-17 19:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

The USGS tidal gauge in Hudson Bay at Freeport recorded a peak water level of 5.8 ft. MLLW at 600 pm EST. The moderate coastal flood threshold of 5.8 ft. MLLW was reached from 548pm to 618pm EST. The moderate coastal flooding thresholds were established by the National Weather Service, based on impact analysis and collaboration with the USGS and local emergency management.

Coastal Flood in SOUTHWEST SUFFOLK, NEW YORK
From 24-JAN-17 04:00:00 to 24-JAN-17 10:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

The USGS tidal gauge in Great South Bay at Lindenhurst recorded a peak water level of 4.3 ft. MLLW at 636 am EST. The major coastal flood threshold of 4.3 ft. MLLW was reached from 612am to 724am EST. The moderate coastal flood threshold of 3.8 ft. MLLW was reached from 418am to 912am EST. The moderate and major coastal flooding thresholds were established by the National Weather Service, based on impact analysis and collaboration with the USGS and local emergency management.

Coastal Flood in SOUTHEAST SUFFOLK, NEW YORK
From 24-JAN-17 06:00:00 to 24-JAN-17 10:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

The USGS tidal gauge on the Peconic River at Riverhead recorded a peak water level of 6.6 ft. MLLW at 748 am EST. The moderate coastal flood threshold of 6.1 ft. MLLW was exceeded from 618am to 930am EST. The moderate coastal flooding thresholds were established by the National Weather Service, based on impact analysis and collaboration with the USGS and local emergency management.

Coastal Flood in SOUTHERN NASSAU, NEW YORK
From 24-JAN-17 04:00:00 to 24-JAN-17 07:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

The USGS tidal gauge in Hudson Bay at Freeport recorded a peak water level of 6.4 ft. MLLW at 518 am EST. The moderate coastal flood threshold of 5.8 ft. MLLW was exceeded from 330 to 654 am EST.  The USGS tidal gauge at East Rockaway Inlet at Atlantic Beach recorded a peak water level of 7.3 ft. MLLW at 442 am EST. The moderate coastal flood threshold of 7.0 ft. MLLW was exceeded from 418 to 554 am EST. The USGS tidal gauge at Reynold Channel at Point Lookout Inlet recorded a peak water level of 6.8 ft. MLLW at 518 am EST. The moderate coastal flood threshold of 6.6 ft. MLLW was exceeded from 406 to 606 am EST.The moderate coastal flooding thresholds were established by the National Weather Service, based on impact analysis and collaboration with the USGS and local emergency management.