Storm Surge Definitions: STORM SURGE is the increase in water level due to a storm (hurricane) STORM TIDE is the total water level measured above a reference datum during a storm (the combination of astronomical tide and storm surge). EXTRATROPICAL STORM SURGE is the storm surge due to a storm that forms outside of the tropics. A typical example would be a “Nor’Easter”.

Tide with Storm Surge DUNE DUNE STORM SURGE STORM SURGE STORM SURGE HIGH TIDE STORM SURGE STORM SURGE STORM SURGE MEAN TIDE (MSL) LOW TIDE

b. Side view of Cross Section “ABC” DEEP WATER a. Top view of Sea Surface b. Side view of Cross Section “ABC” A B C Wind Eye A B C 0’ 5O’ 100’ 150’ 200’ MSL Current

b. Side view of Cross Section “ABC” LANDFALL a. Top view of Sea Surface and Land b. Side view of Cross Section “ABC” Sand Dunes on Barrier Island A B C Wind Wind Wind STORM SURGE Eye 0’ 5O’ 100’ 150’ 200’ MSL A B Current C Barrier Island Mainland Continental Shelf

Individual Grid Sub-grid elements: 1 dimensional flow for rivers and streams Barriers Cuts between barriers Channel flow with chokes and expansions Increased friction for trees and mangroves Individual Grid Barrier Stair Step Rise Water Surface above a square Transport Points Water Depth above a square Surge Points DATUM

SLOSH Basins

Wind Input To SLOSH Embedded parametric hurricane wind model requires: TRACK Positions - Latitude & Longitude INTENSITY of the Storm - (change in pressure) (not observed wind speed) SIZE of the Storm - Radius of maximum wind Wind Model solves a differential equation for wind speed and direction Forward speed is incorporated into asymmetry. Advantages: Universal (not “calibrated” to location) Utilizes “forecastable” hurricane parameters (Does have errors) Tested on many past hurricanes

SLOSH Model Model runs and creates a rexfile and an “envelope of high water”. The “Envelope” is the highest the water got in a particular grid cell during the Model run. Designed for use with hurricane evacuation planning MEOW: Maximum Envelope of Water Highest water due to a family of parallel tracks with same direction, speed and intensity MOM: Maximum of MEOWs Highest water due to a set of MEOWs. Rex File: Enables us to start to use it for real-time storm surge forecasting. (only used about 12 hours before projected landfall) FEMA HLT (Hurricane Liaison Team) Intent is for first response and recovery Convert envelope in real time to ESRI ArcGIS .shp files Used as input to hydrology’s DWOPER river model Historical hurricane runs