Local NWS WFO Efforts to Measure Storm Surge and Gauge Impacts to Support Improved Forecasting and Impact Recognition and Communication

Coastal areas are especially vulnerable to flooding caused by storm surges from hurricanes, tropical storms and strong extra-tropical low pressure systems. It is a challenge to predict the location and magnitude of storm surge as well as communicate the threat to coastal communities. Specific storm surge information is vital to local communities that use the data to prepare and take protective action in advance of storms reaching shore. Complex modeling used to make predictions of storm surge relies on accurate post-storm measurements of storm surge. The post-storm measurements are used in and are important to both model development and validation. In addition it is important for a local National Weather Service (NWS) Weather Forecast Office (WFO) to gain a better understanding of how various storm surge magnitudes impact on their area of responsibility.

The National Hurricane Center (NHC) Storm Surge Unit introduced an experimental Potential Storm Surge Inundation Graphic in 2014, which utilizes the probabilistic storm surge exceedance forecast data to show high resolution above ground inundation mapping. The network of official tide gauges from the National Ocean Service (NOS) is quite sparse spatially to be utilized for verification purposes to gauge the effectiveness of this graphic. In addition, the network of NOS gauges is not configured to relay actual above ground measurements. Although some research entities along with the United States Geological Survey (USGS) can deploy storm surge sensors prior to significant events and take high water mark surveys following events, this does not always occur.

The NWS WFO in Newport, NC developed local procedures for measuring storm surge utilizing high water mark surveys following Hurricane Irene in 2011 and Sandy in 2012. Beginning in 2012, the office helped to lead a National Oceanic and Administration (NOAA) Southeast Caribbean Regional Team (SECART) project to improve collaborative efforts to measure storm surge. This project was funded as part of a joint funding opportunity from the NOAA National Sea Grant College Program and Office of Program Planning and Integration.

Following Hurricane Arthur in 2014, the WFO in Newport, NC applied some of the techniques developed as part of the SECART project, as well as experience gained through surveying past storms, to document Arthur's storm surge. The result was an increased density of storm surge measurements along the Pamlico Sound of NC. The measurements showed that the peak surge from Arthur occurred between the sparsely-located NOS tide gauges. This allowed for better spatial verification and understanding of the accuracy of the new NHC Potential Storm Surge Inundation Graphic.

By having local NWS personnel survey the storm surge, they were also able to gauge the impacts associated with the level of surge observed. In addition, collecting this data for each storm that affects the area allows for the development of an impacts catalog, and surveying high water mark locations presents opportunities to identify locations that have received record flooding for High Water Mark sign implementation. The High Water Mark signs can be a great outreach opportunity to educate the public to potential storm surge impacts.

The effort to better document and understand storm surge and its impacts greatly improves the ability to forecast and communicate storm surge impacts in the future. This is an important effort that contributes to building a Weather Ready Nation.