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Hurricanes - September 2022

179 years of Hurricane & Tropical Storm data from 1842 to 2021. This feature layer, utilises data from the National Oceanic and Atmospheric Administration (NOAA), displays all hurricane tracks in the world for the last 179 years. This data has been reduced down to the past 10 years, from 2011 to 2021. 

 

The Coriolis effect or force means that in 24 hours a point on the equator must complete a rotation distance equal to the circumference of the Earth, which is about 40,000 km. A point right on the poles covers no distance in that time; it just turns in a circle. So, the speed of rotation at the equator is about 1600 km/hr, while at the poles the speed is 0 km/hr.

 

Observations show that no hurricanes form within 5 degrees latitude of the equator. The Coriolis force is too weak to get air to rotate around in an area of low pressure – rather than flow from high to low pressure. If you can't get the air to rotate you can't get a storm. The Coriolis is a necessary ingredient to make a storm, but it may also pull the storm away from the equator – making crossing the equator a tough trick to pull off.

 

Hurricane Ian made landfall in Florida on the 29th of September (NZT). At least 31 people are confirmed dead (1 October), including 27 people in Florida mostly from drowning, but others from the storm’s tragic aftereffects.  An elderly couple died after their oxygen machines shut off when they lost power, authorities said. Now weakened to a post-tropical cyclone, Ian was expected to move across central North Carolina on Saturday then move into Virginia and New York.

 

While it is difficult to define the impact of the climate crisis on any specific storm or extreme weather event, scientists agree that global heating makes storms like Ian more common – and dangerous.

As sea levels rise, flooding from storms is projected to get worse. In the case of Hurricane Ian, data from NOAA suggest that had the same storm occurred in the 1960's, its impact might have been at least slightly diminished. Sea levels in Fort Myers have risen about half a foot since then.

Warmer conditions – and a warmer planet – also drives more flooding, research has shown. A warmer atmosphere can hold more water vapor – and a study found that in 2017, record high temperatures driven in part by global heating increase the amount of rain that Hurricane Harvey poured down.

And finally, warmer water can increase the speed and intensity of a hurricane – fuelling how fast it spins. Studies suggests that hurricanes in the Atlantic are more likely to gain power more quickly as the earth warms.

 

How did they name this Hurricane Ian and how are the names decided?

 

After crashing through the Caribbean, Hurricane Ian is heading towards Florida with winds up to 155mph (250 km/hr) and millions of people in its path. Hurricanes like Ian and tropical storms are given names to help communicate forecasts and warnings to the public. They used to be named with their longitude and latitude or the year and order with which they came, which was pretty confusing.

 

So, during World War II, military meteorologists in the Pacific started naming tropical storms with women’s names. And it worked so well that the National Hurricane Centre started doing it for the Atlantic. By 1978, meteorologists realised that maybe we should be giving them men’s names too. So Atlantic Hurricanes are named from a list of male and female names that’s used on a 6-year rotation. It’s a list of 21 names used in alphabetical order, but excluding the letters Q, U, X, Y, & Z. Usually there are not more than 21 tropical storms a year, but if needed there is a supplementary list that’s used by the World Meteorological Organisation. So, this means that names do get used more than once. Ian’s been used 8 times for tropical storms. 2022 Hurricane Ian is not to be confused with 2016 Tropical Storm Ian in the Atlantic or the 1996 Tropical Storm Ian in the Western Pacific. But names can be retired if the hurricanes cause significant damage and fatalities, and that is why we will never see another Hurricane Katrina.

 

The 1996 – ‘97 South Pacific cyclone season was one of the most active and longest South Pacific tropical cyclone seasons on record, with 12 tropical cyclones occurring within the South Pacific basin between the longitudes of 160°East and 120°West. The season officially ran from November 1st, 1996, to April 30th, 1997, however, the season ended later than normal with three systems monitored after the official end of the season. The strongest tropical cyclone of the season was Cyclone Gavin a ‘Severe Category 4 Tropical Cyclone’, responsible for at least 25 deaths as it affected Fiji and parts of Polynesia, before it was retired from the tropical cyclone naming lists. Major damage was felt in Tuvalu, Wallis & Futuna, and Fiji – before moving southwards, out of the tropics to New Zealand. Where we recorded flooding in Northland, Waikato, Bay of Plenty and Gisborne, which led to road closures.

 

In Fiji alone, major destruction of sugar cane and other food crops occurred, while the 25 attributed deaths were felt here. This included 10 people lost at sea when a fishing vessel, the Wasawasa I, sank, and another 15 deaths caused by landslides, electrocution, and drowning. After the season had ended 5 tropical cyclone names were retired from the naming lists, after the cyclones had caused significant impacts to the South Pacific: Drena, Fergus, Gavin, Hina, and Keli.

 

Geography, digital geography has a role to play in the various outcomes of Climate Change, watch this space as new technologies and methodologies evolve in our ever-changing world.

- Matt Couldrey [geoid - digital geography]

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