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The maps below show predictions from preliminary runs of the numerical model SLOSH for storm surge levels along Mobile Bay, AL. These model predictions were provided by the National Hurricane Center and used input from NHC forecast advisories. They do not represent final products and were produced to aid planning by emergency managers and initial response workers. They are preliminary and will be improved as more accurate inputs are used. The values presented represent the maximum surge value observed at each grid cell over the duration of the model run. On each map, the USGS added the shoreline (black line) and major roads (heavy blue lines). Click on the links below the map to load the larger versions.
Mobile Bay, AL SLOSH Data (NOAA)
(map updated 09-09-2005)
medium version: al_mobile_bay_k27_mobMED.jpg (502 KB)
large version: al_mobile_bay_k27_mobLG.jpg (1.3 MB)
Send suggestions for improvements to the maps to:
Kristy Guy
kguy@usgs.gov
727-803-8747 x3063
Storm surge, the temporary rise in water level due to winds and pressure forces related to a hurricane, resulting from Hurricane Katrina was modeled by the National Hurricane Center using the NOAA SLOSH (Sea, Lake and Overland Surges from Hurricanes) model, a real-time forecast model for hurricane-induced water levels for the Gulf and Atlantic coasts. The numerical model is based on linearized, depth-integrated equations of motion and continuity (Jarvinen and Lawrence, 1985). Changes in maximum surge elevations are forced by time-varying wind-stress and pressure gradient forces which depend on the hurricane's location, minimum pressure, and size measured from the eyewall out to the location of maximum winds (Jarvinen and Lawrence, 1985). The SLOSH model does not incorporate astronomical tides, wave runup or setup; however, astronomical tides are included in the final results (Houston et al., 1999). While the results are location specific, accounting for local water depths, proximity to bays and river, etc., the results are accurate to ± 20% of the calculated value (2004). Error in SLOSH values can also arise from differences between the parametric wind models which force SLOSH and the hurricane's actual wind field (Houston et al., 1999).
NOAA, 2004. Hurricane Preparedness. National Centers for Environmental Prediction, National Hurricane Center, www.nhc.noaa.gov/HAW2/english/surge/slosh.shtml.
Houston, S.H., Shaffer, W.A., Powell, M.D. and Chen, J., 1999. Comparisons of HRD and SLOSH surface wind fields in hurricanes: Implications for storm surge modeling. Weather and Forecasting, 14: 671-686.
Jarvinen, B.R. and Lawrence, M.B., 1985. An evaluation of the SLOSH storm surge model. Bulletin of the American Meteorological Society, 66(11): 1408-1411.
