Operational Wave Guidance at the U.S. National Weather Service during Tropical/Post–Tropical Storm Sandy, October 2012*

Abstract

Abstract Waves generated during Hurricane Sandy (October 2012) contributed significantly to life and property losses along the eastern U.S. seaboard. Extreme waves generated by Sandy propagated inland riding high water levels, causing direct destruction of property and infrastructure. High waves also contributed to the observed record-breaking storm surges. Operational wave-model guidance provided by the U.S. National Weather Service, via numerical model predictions made at NOAA’s National Centers for Environmental Prediction (NCEP), gave decision makers accurate information that helped mitigate the severity of this historical event. The present study provides a comprehensive performance assessment of operational models used by NCEP during Hurricane Sandy, and makes a brief review of reports issued by government agencies, private industry, and universities, indicating the importance of the interplay of waves and surges during the hurricane. Performance of wave models is assessed through validation made relative to western Atlantic NOAA/NDBC buoys that recorded significant wave heights exceeding 6 m (19.7 ft). Bulk validation statistics indicate a high skill of operational wave forecasts up to and beyond the 3-day range. Event-based validation reveals a remarkably high skill of NCEP’s wave ensemble system, with significant added value in its data for longer forecasts beyond the 72-h range. The study concludes with considerations about the extent of severe sea-state footprints during Sandy, the dissemination of real-time wave forecasts, and its impacts to emergency management response, as well as recent upgrades and future developments at NCEP that will improve the skill of its current wave forecasting systems, resulting in more reliable wave forecasts during life-threatening severe storm events in the future.