1. National Weather Service SLOSH S ea, L ake, and L ake, and O verland O verland S urges from S urges from H urricanes H urricanes Part 1: W. Shaffer / MDL Part 2: B. Jarvinen / NHC

2. National Weather Service DEFINITIONS: STORM SURGE is the increase in water level due to a storm (hurricane / tropical storm / high winds). STORM TIDE is the total water level during a storm = Astro Tide + STORM SURGE + Rainfall Runoff + Anomaly = Astro Tide + STORM SURGE + Rainfall Runoff + Anomaly

3. National Weather Service b Storm tide 8.1 ft

4. National Weather Service Storm tide 8.1 ft Predicted Tide 0.9 ft

5. National Weather Service Storm tide 8.1 ft Predicted Tide 0.9 ft Storm Surge = Storm Tide – Predicted tide

6. National Weather Service Storm tide 8.1 ft Predicted Tide 0.9 ft Storm Surge = Storm Tide – Predicted tide = 8.1 – 0.9 = 7.2 ft

7. National Weather Service SLOSH Hurricane Storm Surge Model Solves shallow water equations Orthogonal curvilinear grid system 2-dimensional (2 ½ dimensional ???)

8. National Weather Service SLOSH Hurricane Storm Surge Model Overland flooding Sub-grid Features: 1-dimensional flow for rivers and streams barriers cuts between barriers channel flow, with chokes and expansions Increased friction for trees and mangroves

9. National Weather Service

10. DATUM Stair Step Rise Barrier Dry and wetted grid squares. The squares are two-dimensional stair steps. Surge Points Transport Points Water Depth above a square Water Surface above a square Individual Grid

11. National Weather Service

15. Topo/Bathy Data Sources USGS NGDC LSU

16. National Weather Service

17. SLOSH Hurricane Storm Surge Model Embedded parametric hurricane wind model Uses a normalized wind profile Solves diff eqn for wind speed and direction (Direction is NOT specified a priori) Uses pressure, not observed wind speed Forward speed incorporated into asymmetry

18. National Weather Service SLOSH Hurricane Storm Surge Model Universal, not “calibrated” to location Utilizes “forecastable” hurricane parameters Tested on MANY past hurricanes

19. National Weather Service INPUT TO SLOSH TRACK Positions - latitude & longitude INTENSITY - (pressure drop) SIZE - Radius of maximum wind

20. National Weather Service

21. SLOSH Hurricane Storm Surge Model Designed for hurricane evacuation planning Used as input to hydrology’s DWOPER river model – forecast hydrograph at selected locations used to initialize wave which propagates up river Being used for real-time surge forecasting near landfall time (beginning 24 hours before projected landfall)

22. National Weather Service

23. SLOSH Hurricane Storm Surge Model Model output: MOM’s and MEOW’s Individual runs – in real time Historical hurricane runs Probabilistic surge forecasts Available in SLOSH display format GIS format (ArcView or MapInfo) Animations (on web)

24. National Weather Service SLOSH Hurricane Storm Surge Model Not included currently: explicit tide computation wave setup and runup

25. National Weather Service

26. http://www.nws.noaa.gov/mdl/etsurge/

27. National Weather Service Verification of computed surges for past hurricanes

28. National Weather Service