Use of Probabilistic Storm Surge Guidance and Inundation Mapping during Dorian and the Impacts on Evacuation Decision-Making and Execution

Hurricanes such as Katrina, Ike, and more recently Isaac, Sandy,

Hermine, and Matthew have highlighted the need for improved storm surge

forecasting, mapping, and communication mediums. Similarly, trends in

population and increasing evacuation clearance times are necessitating

more refined evacuations during hurricanes. To address these issues,

the National Weather Service has been engaged in a decade-long

initiative aimed at improving the accuracy of storm surge forecasting

techniques and GIS inundation mapping products for emergency management.

Working with social science researchers from disciplines such as

sociology, communications, and geography, the National Weather Service

has engaged its users and partners to determine the best path forward.

The social science research concluded that the implementation of an

explicit storm surge warning, accompanied by high-resolution storm surge

inundation graphics, was supported overwhelmingly by the emergency

management and broadcast meteorologist communities, and that these tools

would have the greatest potential to increase the understanding and

awareness of, and response to, the storm surge hazard. Accordingly, the

National Weather Service implemented an operational high-resolution

inundation graphic, and accompanying GIS datasets, in 2016, and the

first-ever explicit storm surge watch/warning product in 2017. While

the aforementioned products have been extensively evaluated from a

physical science perspective (i.e. accuracy and reliability), to date

there has been limited evaluation of the impacts of these new offerings

on evacuation decision making and execution. This paper will analyze

the results from recent storms, such as Irma and Dorian to determine the

trends in evacuation effectiveness using recent advancements in storm

surge communication and forecasting techniques.

This talk will focus on P-Surge advancements since 2018. This includes developing ways to use the latest south Florida SLOSH basin, which has a significantly larger number of grid cells due to a higher resolution and broader extent. It also includes using different climatological error statistics based on whether the initial maximum wind speed of the storm is a tropical depression, tropical storm, or hurricane.