More than half of all hurricane-related deaths are caused by storm surges, yet few consider it a factor when trying to decide whether or not to evacuate their homes. But starting this hurricane season, national forecasters will warn people using color-coded storm surge maps.
No doubt, storm surges are a serious issue. Along vulnerable coasts, they pose the greatest threat to life and property from a hurricane. Large death tolls have been known to result from the rise of oceans when major hurricanes reach land. Back in 2005, for example, Hurricane Katrina caused at least 1,500 deaths, many of which occurred directly or indirectly as a result of storm surge.
Storm surge vs. storm tide (credit NOAA)
Hence the new maps. And indeed, a prime motivation for developing this service was on account of the over-emphasis placed on a hurricane's wind strength.
It took the NOAA several years to develop the system as it consulted with emergency managers, broadcast meteorologists, and others. The new map will show geographical areas where inundation from storm surge could occur and how high above ground the water could reach in those areas.
The first map will be issued at the same time as the initial hurricane or tropical storm watch is announced (typically 48 hours before landfall). It will be based on the latest forecast track and intensity of the storms, while showing inundation levels that have a 10% change of being exceeded. That means these maps will represent a kind of worst-case scenario for any given location. The NOAA hopes to have the maps updated every six hours.
The map will be part of an interactive display made available on the NHC website when hurricane watches and warnings are in effect for portions of continental United States.