SLOSH Model MOMs: A National View of Inundation

NOAA, specifically the National Weather Service's (NWS) National Hurricane Center (NHC), utilizes the hydrodynamic SLOSH (Sea, Lake, Overland Surges from Hurricanes) model to simulate storm surge, both its height and inland extent, under varying scenarios. This information is then provided to the federal, state, and local partners to assist in a range of planning processes, risk assessment studies, and decision making. Operationally, SLOSH model simulations are performed in 28 basins (or grids) along the U.S. coastline. Based on climatology for each region, tens of thousands of hypothetical hurricanes are simulated in each basin and the potential storm surges are calculated. Composites of the various storm surges – Maximum Envelopes of Water (MEOWs) and Maximum of Maximums (MOMs) – are then created to assess and visualize the storm surge risk under varying conditions.

While MOMs and MEOWs provide a reasonable local assessment of storm surge risk, they do not provide a National snapshot owing to use of 28 unique SLOSH grids. National storm surge assessments must therefore merge together all the grids or do individual, location by location, analyses. Such analyses are very laborious and merging the basins requires considerable SLOSH model and hydrodynamic modeling expertise. Collectively, these limitations inhibit reliable National level analysis of storm surge risk and vulnerability. This paper describes the technical process to generate a seamless GIS product of inundation (i.e., depth of water above ground) for Category 1-5 Hurricanes. A similar technique will be used to create the NHC inundation graphic that is scheduled for experimental release during the 2014 Atlantic Hurricane Season.