Hurricane Florence Case Study
Hurricane Florence made landfall on Friday, 14th September 2018, with the storm’s centre striking Wrightsville Beach in North Carolina, with gales of up to 90mph (150 km/h).
August to October is peak hurricane season when conditions are primed to create the perfect storm. The strongest storms originate off the west coast of Africa because they have two weeks’ worth of warm water to build up over.
The storm started to form due to an area of low pressure over Western Africa. High moisture levels in the air and low wind sheer formed showers and thunderstorms. Easterly trade winds transported the weather system west north-west across the Atlantic, after travelling 2000km across the Atlantic an eye formed signifying the birth of a tropical storm.
Hurricanes start within 5º and 30º north and south of the equator, where surface sea temperatures reach at least 26.5ºC. The air above the warm sea is heated and rises. This causes low pressure. As the air rises, it cools and then condenses, forming clouds. The air around the weather system rushes in to fill the gap caused by the rising air. The air begins to spiral. The spinning movement of the earth causes this.
Florence stayed strong because no land was in its path across the Atlantic to slow the storm’s progress. The hurricane reached category four as it approached the east coast of the USA. However, it reduced to category 1 when it made landfall and was subsequently downgraded to a tropical depression. The tweet below shows Florence’s route across the Atlantic.
Florence’s path across the Atlantic from August 29 through today. pic.twitter.com/6EiUntz8CR
— Daniel Bonds (@Daniel_Bonds) September 16, 2018
Once Hurricane Florence made landfall, wind speeds reduced, and the storm stalled, travelling only 5 miles per hour. This led to a huge volume of rain falling across North and South Carolina.
Up to 1.7 million people were ordered to evacuate across the US states of South Carolina, North Carolina and Virginia. TV news encouraged people to evacuate. The video below is an example that was broadcast on local TV networks.
Organisations such as the South Carolina Emergency Management Division use websites, social media, TV and radio to warn residents of the state of emergency declared prior to Hurricane Florence making landfall. Advice on how to prepare for a hurricane is also published online.
Highways became one-way streets to support evacuation from the area. Lane reversal enabled residents to evacuate more quickly.
— Planet Green (@PlanetGreen) September 13, 2018
Residents put protective measures in place for their properties. This included boarding up windows.
Law enforcement remained to ensure the risk of looting of businesses and residential properties was reduced. This encouraged more people to evacuate.
Prior to the hurricane making landfall, attempts were made to enforce the line by reinforcing beaches in advance of the forecast storm surge.
Storm surge has begun to overwash the dunes during the last hour on the incoming tide. Sending well wishes to that brave operator working to hold the line. #Florence #NC12 #OBX pic.twitter.com/BvA1k4FfAQ
— Michael Flynn (@RippleEnviro) September 13, 2018
A flash flood emergency was put in place for portions of the Charlotte, NC Metro area.
In 2012, North Carolina legislators passed a bill that barred policymakers and developers from using up-to-date climate science to plan for rising sea levels on the state’s coast.
Conservative state Rep. Pat McElraft, whose top campaign contributors were the North Carolina Association of Realtors and the North Carolina Home Builders’ Association, drafted a bill in response that rejected the panel’s sea level rise predictions. https://t.co/1SGom8FpGL
— Keren Prize Bolter (@SLRBrowardFL) September 13, 2018
Although the hurricane was downgraded to category one when it made landfall, there was still a significant storm surge. Storm surges occur due to the low pressure of the air over the ocean, causing it to rise. In addition to this, strong winds transfer energy to waves. This forms the eye pile. It gets dragged along with the eye.
— Kathryn Farrell (@KateAFarrell) September 14, 2018
The tweet below shows the storm surge flow between two homes on the coast.
Surf flows between two homes on Ocean View Drive in Avon pic.twitter.com/P38jYtMKVT
— Jeff Hampton (@jeffhampton56) September 13, 2018
While the wind speed was reduced, the risk to people living in the areas in Florence’s path was flash flooding caused by the vast amounts of rain already soaking the region and storm surges.
This is caused when high tides and rising waters from the shoreline work their way inland, “reversing” the flow of rivers and flooding normally dry areas.
Some parts of North Carolina experienced surges as high as three metres in places, devastating people’s homes and businesses. Meteorologists warned floodwaters could rise up to four metres during the storm.
Florence dumped approximately 18 trillion gallons of rainwater. Some areas of North Carolina saw almost 50cm of rain in just a few hours, and video footage showed sea levels begin to surge inland.
At least 37 people died in storm-related incidents. 27 in North Carolina, 8 in South Carolina and 2 in Virginia
Nearly a million householders had no electricity in the Carolinas.
Hurricane-related flooding damaged an estimated seventy-five thousand structures.
Fifteen thousand people were housed in temporary shelters in North Carolina.
Ten mass-feeding kitchens were set up.
Wilmington remained cut off for at least a week following Hurricane Florence, delaying the distribution of food, water and tarps to residents.
All roads in North Carolina were at risk of flooding during the storm. Wilmington, North Carolina, was cut off from the rest of the state after damage from Florence closed major roads in the city of 117,525 people. The main roads into the city were closed or impassable.
To give you an idea of what road conditions are like around the state right now, here’s a look at reported closures, AS OF 1:30 p.m. This is changing rapidly. Stay home, stay safe. View road conditions on #FlorenceNC, here https://t.co/u6edItwCyk. #ncwx pic.twitter.com/vW78qU3Yn4
— NCDOT (@NCDOT) September 16, 2018
Looters raided homes, businesses and cars as the hurricane approached.
— Spectrum News ILM (@SpecNewsILM) September 14, 2018
More than 2,400 flights were cancelled.
Three hundred business properties were damaged in Bern, North Carolina.
1.7 million chickens were killed in North Carolina.
Tobacco, cotton and peanut crops were damaged.
The hurricane caused at least $38 billion in damage.
Heavy rains caused a slope to collapse at a coal ash landfill at a closed power station outside the port city of Wilmington. Two thousand cubic yards of ash were displaced at the Sutton Plant, and contaminated water flowed into the cooling pond. Ash left when coal is burned contains toxic heavy metals, including lead and arsenic.
Heavy rainfall from the remnants of Hurricane Florence sent tens of thousands of gallons of untreated wastewater into a tributary of North Carolina’s Cape Fear River basin. Sixty-three thousand gallons of untreated waste flowed from a sanitary sewer main.
US President Donald Trump has declared a disaster in North Carolina. This released emergency funding to support the affected area, including grants for property repairs and low-cost loans to cover uninsured losses.
Hundreds of residents were plucked to safety from flooded homes in the North Carolina counties of Beaufort and Craven.
Rescuers were hampered by the extensive flooding caused by heavy rainfall.
Michael Jordan donated $2 million to hurricane relief efforts.
— Tony scar. (@gourdnibler) September 14, 2018
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