Ian: Science Behind the Surge and Impact

The world has been following Hurricane Ian for over a week now, from its humble beginnings as a cluster of thunderstorms north of Venezuela to its destruction in Cuba, Florida, and finally in Georgia, and the Carolinas. This massive Category 4 storm measured winds nearly 155 mph, and in addition to wind damage caused deadly storm surge and flooding. Those impacts won’t be fully quantified for weeks, due to how widespread and prolonged they have been. This storm encountered special circumstances, particularly in southwestern Florida, that made it as devastating as it was.

Corresponding high resolution NOAA hurricane response imagery of this same location on Ft. Myers Beach. Before (above). After (below). Large concrete buildings are still visible, but you can see many smaller structures swept away.

According to the National Hurricane Center: “Storm surge is an abnormal rise of water generated by a storm.” While that may seem like a simple definition, it’s much more complicated than that. Let’s break it down:

  • A hurricane is an organized area of low pressure with sustained winds greater than 74 miles per hour, moving counterclockwise around its center in the northern hemisphere.
  • Due to the physics of low pressure, upward vertical motion is observed in the center.  
  • Due to the conservation of a fluid mass, what goes up in the storm must be replaced below and this essentially creates a vacuum at the center base of a hurricane, pulling water up and moving it with the storm. This accounts for part of the storm surge.
  • Just around the center of the hurricane, extreme winds make it to the surface. This physically pushes the water in whatever direction the winds are going. This accounts for the other part of the storm surge.
Image above: NOAA/Wind and Pressure Components of Hurricane Storm Surge

As Hurricane Ian gained strength, meteorologists knew that that intensity of wind would contribute to a devastating storm surge. In fact, we could already see the opposite of storm surge happen in Tampa Bay before the hurricane made landfall. Nearly a day before landfall, north of where landfall occurred, wind was moving east to west across Tampa Bay. This allowed for the water to physically be pushed out to sea, creating beaches where water once sat.

The aftermath of Hurricane Ian is visible in the Sentinel 2 image of September 30. This zoomed view shows the largest sediment plume discharging into the coastal waters of West Florida in the area of landfall. Image shared via @ai6yerham, Twitter

Conversely, south of the eye of the storm, wind moved from west to east, creating devastating consequences for Naples and Fort Myers who saw the water so easily be thrown onto land with their low sea level positioning, and the coincidence of high tide occurring. What would normally have been high tide at a depth of 1.3ft in Fort Meyers on Wednesday the 28th, turned into 8.57 feet (NOAA Tides and Currents).

Storm surge flood damage in Fort Myers, Florida after Hurricane Ian, September 2022. Photo: US Coast guard

Through aerial imagery, NOAA identified widespread flooding and wind damage through Fort Myers, Naples, and Cape Coral. Search and rescues are still ongoing several days after the landfall in these areas. Flash Flood Emergencies were issued by the National Weather Service across the state late last week due to over 15 inches of rainfall across the peninsula. Additionally, freshwater river flooding is still being observed in Sarasota and levee breaks continue to flood homes.

This hurricane wasn’t only devastating to Florida. As it crossed the peninsula, it weakened into a tropical storm and then re-strengthened into a hurricane before it made landfall once more near Georgetown,  South Carolina. Though it wasn’t a Category 4, the impact was still felt due to storm surge and intense rainfall rates which combined created flooding in vulnerable, close to sea level locations. Some areas in coastal South Carolina received 6 to 8 inches of rain, as Ian approached with a roughly 6 foot anomaly in the tide.

Hurricane Ian was a natural disaster that disrupted the crucial infrastructure that businesses and the supply chain rely so heavily on. Across Ian’s path, airports were shut down, shipping vessels had to be rerouted, roads and causeways were washed out, and much, much more. The consequences and disruptions felt by just one area of the supply chain will then translate to the next stop in the journey for that entity, and it goes on from there.

A Few Economic Impact Stats:

Estimates from CoreLogic: (Cited in CNN Business)

  • Between 28 and 47 billion dollars of insured losses between wind damage and flooding damage for the State of Florida.
  • Conversely, Hurricane Andrew insured losses were 26.5 billion, and resulted in the most expensive storm in Florida history.
  • The economy in Florida heavily relies on tourism and agriculture. Damage to agricultural production will likely drive up costs on items such as Citrus, and popular tourist destinations in cities such as Fort Myers will need years to rebuild.
  • More than 2.6 million lost power according to poweroutages.us during the worst of the storm.
  • Power outages have major impacts to the supply chain, especially when manufacturing sites are without power or generator backups

Generally, after a forecast is given of an impending hurricane, businesses will make every effort to prepare for the incoming storm by adjusting operations, rerouting products, and preparing generators to revive the power grid. This makes the forecast those businesses receive crucial, and this is how we can help.

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