The Flood Insurance Rate Maps (FIRMs) produced by FEMA and the Hurricane Inundation/Evacuation Maps produced by the National Oceanic and Atmospheric Administration's (NOAA) maps are fundamentally different. NOAA's Hurricane Inundation/Evacuation Maps depict areas that are subject to hurricane surge inundation for established storm intensities (usually the Saffir-Simpson scale). The FIRMs depict the areas subject to inundation by the 1-%-annual-chance flooding and the water surface elevations having a 1-%-annual-chance of exceedance.
There are no consistent probabilities of flooding associated with the NOAA inundation/evacuation maps. There are no storm categories associated with FIRMs. There are also differences between the models and the underlying methodologies. For example, NOAA's maps do not incorporate wave effects while FIRMs do.
Thus, there is no direct or consistent comparison between Special Flood Hazard Areas (SFHAs) shown on FIRMs and surge inundation areas shown on Hurricane Inundation/Evacuation Maps; or between Base Flood Elevations (BFEs) and water elevations produced by NOAA's SLOSH (Sea Lake and Overland Surges from Hurricanes) model. For example, the area flooded by the base flood at one location may be roughly equivalent to Category 2 hurricane inundation, but at another nearby area, it may be closer to a Category 1 inundation or a Category 3 inundation.