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Storm Surge
Mon Jun 06, 2005
Listen in RealAudio 
For those living in a hurricane’s path, storm winds create the biggest fear. But records
show that the most deadly feature is the storm surge, which claims nine of ten
hurricane victims. Hi, I’m Bryan Yeaton, for The Weather Notebook.
Storm surge is water pushed toward shore by the system’s various forces. Surge
height depends on the storm’s forward speed, its wind speed and central
pressure.
We once believed storm surge resulted solely from water drawn upward into the
storm’s center where atmospheric pressure is lowest. For each inch of mercury drop
in central pressure, water level rises 1.13 feet. Now we know the storm’s forward
speed and wind speed determine most of the surge height at sea, typically raising a
dome of water ahead of the storm 35-50 miles across and 6-15 feet above normal sea
level. Hurricane winds raging at 140 mph produce a 16-foot surge.
The astronomical tides also influence surge height as the storm nears the shoreline. A
storm arriving on high tide produces a worst surge scenario.
When the hurricane makes landfall, offshore water depth and the local coastline
topography alter the surge’s height and damage potential. Impacts, including severe
coastal flooding, can vary significantly over shoreline separated just a few
miles.
As water weighs one thousand times more than a similar volume of air, its force is
much more destructive than even hurricane-force winds. When the surge lines up with
the right wavelength, it can strike with a force of 10,250 pounds per square foot,
enough to demolish most shoreline structures.
In the US, the highest storm surge ever recorded, in excess of 25 feet, was generated
by Hurricane Camille in 1969. Australia’s 1899 Bathurst Bay Hurricane holds the world
record at 43 feet.
Thanks to our contributing writer, meteorologist Keith Heidorn. Our show is generously
funded by Subaru of America.
Today's Links
Weather Almanac
http://www.islandnet.com/~see/weather/almanac/arc2004/alm04sep.htm
Hurricane Preparedness
http://www.nhc.noaa.gov/HAW2/english/storm_surge.shtml
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