Storm Surge: A Hurricane's Biggest Threat

One of the biggest dangers of a hurricane or tropical storm is storm surge. More deaths result from flooding caused by storm surge than from a hurricane`s winds.

What Exactly is Storm Surge?

Storm surge is literally a dome or wall of water that plows ashore during a hurricane or tropical storm. This wall of water is produced by the force of a storm`s winds on the waters over which the storm moves. The rush of water can reach more than 15 feet high, scouring away buildings, roadways and anything else in its path.

Storm surge is usually maximized in the northeast quadrant or region of a tropical storm or hurricane. This is the result of the storm`s strongest winds usually being found in this part of the storm. The stronger the winds, the greater the volume of water that can be pushed ashore.

Low-lying areas nearest the coastline are the most vulnerable.

Deadly Lessons from the Past

A particularly deadly and destructive storm surge, estimated to be greater than 30 feet in some areas, crashed onto the Gulf Coast as Hurricane Katrina roared ashore August 29, 2005, near Buras-Triumph, La. Catastrophic damage was done to more than 100 miles of the Louisiana, Mississippi and Alabama coastline. The storm is blamed for more than 2,000 deaths and caused more than $115 billion dollars in damage, making it the costliest disaster in U.S. history.

Comparisons have been made between Katrina and Hurricane Camille, which made landfall on August 17, 1969. Camille came ashore near Pass Christian, Miss., bringing with it a dome of water approaching 25 feet high. Nearly every building within a half-mile of the shoreline was washed-away. More than 170 deaths are attributed to the storm, most of which are blamed on the storm surge.

Forecasting the Surge

With storm surge being such a dangerous part of a hurricane, having forecasts that accurate predict their magnitude is extremely important.

The National Hurricane Center (NHC) runs a complex computer model forecast of storm surge called SLOSH. SLOSH stands for Sea, Lake and Overland Surges from Hurricanes. This model takes into account factors such as air pressure, size, forward speed, track and winds of hurricanes in order to estimate storm surge heights. The model has shown an accuracy of plus or minus 20 percent.

Head for Higher Ground

When a hurricane or tropical storm threatens, following evacuation orders can be a lifesaver. People living near the coastline or in flood-prone areas should seek shelter inland until the storm has passed and waters recede.