JACKSONVILLE, Fla. – This hurricane season debuts a new set of watches and warnings for life-threatening storm surge flooding. Areas along the Gulf coast and Atlantic coastline will be considered for the watches and warnings as tropical cyclones approach.
Storm surge is often the greatest threat to lives and property during a tropical cyclone- often times coastal residents can be safe from tropical storms winds by remaining in their homes, when it comes to storm surge flooding, evacuations are often necessary. The vast improvement in the system by having two separate warnings for wind danger and storm surge flooding gives emergency management, media personnel, and the general public much better guidance of the hazards they face as the tropical storm approaches.
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The watches and warnings will be determined by the National Hurricane Center and local National Weather Services offices. The relatively new SLOSH model for storm surge flooding will provide the P-Surge value to help determine when watches and warnings should be issued.
Locally, Hurricane Matthew gave forecasters and the community the first chance to see how the SLOSH (Storm surge flooding prediction) model would behave and how accurate of a picture the forecast would give of what to expect. This graphic shows what the Storm Surge Watch and Storm Surge Warning would have looked like for Hurricane Matthew on the Eastern coastline of Florida.
The National Hurricane Center defines the new watches and warnings:
Storm Surge Watch: The possibility of life-threatening inundation from rising water moving inland from the
shoreline somewhere within the specified area, generally within 48 hours, in association with an ongoing
or potential tropical cyclone, a subtropical cyclone, or a post-tropical cyclone. The watch may be issued
earlier when other conditions, such as the onset of tropical storm-force winds, are expected to limit the
time available to take protective actions for surge (e.g., evacuations). The watch may also be issued for
locations not expected to receive life-threatening inundation, but which could potentially be isolated by
inundation in adjacent areas.
Storm Surge Warning: The danger of life-threatening inundation from rising water moving inland from the
shoreline somewhere within the specified area, generally within 36 hours, in association with an ongoing
or potential tropical cyclone, a subtropical cyclone, or a post-tropical cyclone. The warning may be issued
earlier when other conditions, such as the onset of tropical storm-force winds, are expected to limit the
time available to take protective actions for surge (e.g., evacuations). The warning may also be issued for
locations not expected to receive life-threatening inundation, but which could potentially be isolated by
inundation in adjacent areas.
A product that debuted in 2016, the Potential Storm Surge Flooding Map, will also be available for the 2017 season as well. This graphic highlights geographical areas where inundation from storm surge could occur and the height above ground the water could reach. The map displays water levels that have a 10 percent chance of being exceeded, so it can be considered a "worst case scenario" forecast for any individual location.