Hurricane season runs from June 1st to November 30th. NOAA is predicting a 70 per cent likelihood that it will be a below normal season, 20 percent chance of a near normal season and a 10 percent chance of an above normal season. Scientists warn that even below normal seasons can produce catastrophic impacts to communities.
With the new season, NOAA’s National Hurricane Center will introduce a prototype storm surge watch/warning graphic. It will highlight areas along the Gulf and Atlantic coasts of the United States that have a significant risk of life threatening inundation by storm surge from a tropical cyclone.
This watch or warning will be specific to the storm surge hazard. Historically the warnings have generally been about the storm’s winds. Storm surge can occur at different times and at different locations from a storm’s hazardous winds. Often time’s coastal residents can remain in their homes and be safe from a tropical cyclone’s winds, but evacuations are often needed to keep residents safe from storm surge. Under the new system the National Hurricane Center will issue surge watches 48 hours in advance and surge warnings 36 hours before a cyclone makes landfall.
NOAA describes storm surge as an abnormal rise of water generated by a storm, over and above the predicted astronomical tides. They say it is produced by water being pushed toward the shore by the force of the winds moving cyclonically around the storm. Water weighs 1,700 pounds per cubic yard; extended pounding by frequent waves can demolish any structure not specifically designed to withstand such forces. The elements work together to increase the impact on land because the surge makes it possible for waves to extend inland.
The damage caused by storm surge was experienced firsthand by the people of New Orleans, New York and New Jersey. At least 1500 persons lost their lives during Hurricane Katrina (2005) and many of the deaths were caused directly or indirectly as a result of storm surge. During Hurricane Sandy, the storm surged over Manhattan’s Battery and sent seawater into subways, cellars and tunnels. It destroyed homes and businesses from Queens to the New Jersey coast. Hurricane Katrina caused $108 billion in damages and Hurricane Sandy $50 billion.
The 2015 season maps will become part of a comprehensive program of surge watch and warnings that will be consolidated with the center’s watches and warnings for winds in 2016. When complete, the new process will merge inland and coastal warning information from both threats into a single message. It will be tested for one year and then is expected to be operational in 2017.
This new alert having separate warnings for winds and storm surge should provide better guidance on the hazards the public face when tropical cyclones threaten.
Photo courtesy of NOAA