Wednesday, September 12, 2018

Plotting the Impact of Atlantic Hurricanes on the US

With hurricane Florence bearing down with expected to be devastating force, it might be a good time to reflect on the history of Atlantic Hurricanes on the United States. As an easy if not full proof source for hurricane data I drew on public data collated through Wikipedia's list of costliest Atlantic hurricanes as well as linked articles. On the page it lists 45 hurricanes going back to Hurricane Betsy in 1965, with 30 of them since 2000 totaling 803 billion dollars in estimated damages and 6,591 US fatalities. While this is quite a large number of fatalities, the death toll of Atlantic Hurricanes outside of the US is significantly larger with nearly 30,000 deaths estimated.

Within the US, the track record for deaths from hurricanes tend to be quite low with all hurricanes recorded having a fatality rate of less than two hundred with the exception of Maria (2017 - Trump administration) and Katrina (2005 - GW Bush administration).

Figure 1: US Fatalities by Year.

I have also scaled the y-axis by log10 to make it easier to examine less deadly storms.

Figure 2: US Fatalities by Year Log10 scaled.

Maria and Katrina being the most deadly of storms does not indicate that they are necessarily the most damaging of storms. 

Figure 3: Damages in the Billions by Year.
Harvey and Katrina are reported to have done 125 billions dollars each followed by Maria doing damage of 91.2 billion, Sandy at 68.7, and Irma at 64.8.

So why is it that Harvey (2017 - Trump), a storm that did as much damage as Katrina resulted in only 106 deaths while Maria a storm that did 25% less damage resulted in a US citizen total death toll comparable to the sum of all 44 other Hurricanes on record (2982 vs. 3609)?

Figure 4: Total deaths by Year.

We might attempt to predict which storms might be the most deadly using the storm measurements highest wind speed recorded and lowest pressure recorded.

Figure 5: Wind speed by US_Fatalities
Figure 6: Lowest air pressure recorded in terms of mbar (whatever that is).

As we can see that Maria and Katrina are both on the higher end of  the wind speed distribution and the lower end of the air pressure distribution, we can assert that a more powerful storm is a necessary component for the kind of death tolls associated with these storms.

What factors must be present for a severe storm which otherwise would be associated with a death toll of less than 200 people to being a tremendous human tragedy, such as in the case of Katrina or even more so Maria are yet unknown given the sparsity of data available to the public.

From the data it appears that Atlantic hurricanes have grown more damaging and more deadly for US citizens.

Hopefully, despite the catastrophic blunders of the handling of Katrina and Maria by the Bush and Trump administrations respectively, future hurricanes such as Florence will be dealt with in a more responsible manner.

Code and data can be found here

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