As Hurricane Matthew gets closer to the United States, millions of people will be at risk. Widespread Hurricane Watches and Warnings detail the scope and intensity of this tropical system. These effects will last for several hours, if not days. We want to detail what exactly each risk is and how severe it could be as Matthew tracks along the southeast coast.
Winds from a hurricane can destroy buildings and mobile homes. Debris, such as signs, roofing material, and items left outside can become flying missiles during hurricanes. Winds increase rapidly with elevation in a tropical cyclone. Residents in high-rise buildings should be aware that the winds at the top of a 30-story building will be, on average, about one Saffir-Simpson category higher than the winds near the surface.
Storm surge is the abnormal rise of water generated by a storm’s winds. This hazard is historically the leading cause of hurricane related deaths in the United States. Storm surge and large battering waves can result in large loss of life and cause massive destruction along the coast. Storm surge can travel several miles inland, especially along bays, rivers, and estuaries.
The latest update from the National Hurricane Center is anticipating storm surge above ground level to be near these levels in south Florida as Matthew passes:
- Sebastian Inlet to Savannah River, including portions of the St. Johns River – 6 to 9 feet.
- Savannah River to South Santee River- 3 to 5 feet
- Deerfield Beach to Sebastian Inlet- 3 to 5 feet
- Virginia Beach to Deerfield Beach- 1 to 3 feet
Surge-related flooding depends on the relative timing of the surge and the tidal cycle, and can vary greatly over short distances. Large waves generated by Matthew will cause water rises to occur well in advance of and well away from the track of the center.
Flooding from heavy rains is the second leading cause of fatalities during landfalling tropical cyclones. Widespread torrential rains from tropical storms and hurricanes often cause flooding hundreds of miles inland. This flooding can persist for several days after a storm. Wording included in the Hurricane Warning from the NWS states, “EXTREMELY DANGEROUS AND LIFE-THREATENING WIND IS POSSIBLE. FAILURE TO ADEQUATELY SHELTER MAY RESULT IN SERIOUS INJURY, LOSS OF LIFE, OR IMMENSE HUMAN SUFFERING. MOVE TO SAFE SHELTER BEFORE THE WIND BECOMES HAZARDOUS… STRUCTURAL DAMAGE TO STURDY BUILDINGS, SOME WITH COMPLETE ROOF AND WALL FAILURES. COMPLETE DESTRUCTION OF MOBILE HOMES. DAMAGE GREATLY ACCENTUATED BY LARGE AIRBORNE PROJECTILES. LOCATIONS MAY BE UNINHABITABLE FOR WEEKS OR MONTHS.”
Here are the forecast rainfall totals for the southeast:
- Coastal Eastern Florida, Georgia and South Carolina- 4 to 8″, isolated totals of 12″
- The Florida Keys- 1 to 3″, isolated totals of 5″
Dangerous waves produced by a hurricane’s strong winds can pose a significant hazard to coastal residents and mariners. These waves can cause deadly rip currents, significant beach erosion, and damage to structures along the coastline, even when the storm is more than a 1,000 miles offshore.
Swells generated by Matthew will continue to affect portions of the north coast of Cuba and the Bahamas during the next few days, and will spread northward along the east coast of Florida and the southeast U.S. coast through the weekend.
Tornadoes are often produced by landfalling tropical storms and hurricanes. These tornadoes typically occur in rain bands well away from the center of the hurricane. Right now, the Storm Prediction Center only has a general risk of thunderstorms for this area, but the situation is rapidly changing and residents should stay tuned to local NWS offices for any posted warnings.