Tuesday, September 12, 2017

"A $150 Billion Misfire: How Disaster Modelers Got Irma So Wrong"

We have close to three hundred posts on models. Their essence can be boiled down to two quotes from people smarter about this stuff than I:

"The map is not the territory"
-Alfred Korzybski
"A Non-Aristotelian System and its Necessity for Rigour in Mathematics and Physics" 
presented before the American Mathematical Society December 28, 1931
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"All models are wrong, but some are useful"
-George E.P. Box
Section heading, page 2 of Box's paper, "Robustness in the Strategy of Scientific Model Building"
(May 1979)


And the headline story, from Bloomberg, September 11:
  • Bermuda High kept Irma from becoming the costliest U.S. storm
  • Westward shift and weakening checked ‘astronomical’ damage
Twenty miles may have made a $150 billion difference.

Estimates for the damage Hurricane Irma would inflict on Florida kept mounting as it made its devastating sweep across the Caribbean. It was poised to be the costliest U.S. storm on record. Then something called the Bermuda High intervened and tripped it up.

“We got very lucky,” said Jeff Masters, co-founder of Weather Underground in Ann Arbor, Michigan. If Irma had passed 20 miles west of Marco Island instead of striking it on Sunday, “the damage would have been astronomical.” A track like that would have placed the powerful, eastern eye wall of Irma on Florida’s Gulf Coast.

By one estimate, the total cost dropped to about $50 billion Monday from $200 billion over the weekend. The state escaped the worst because Irma’s powerful eye shifted away from the biggest population center of sprawling Miami-Dade County.

The credit goes to the Bermuda High, which acts like a sort of traffic cop for the tropical North Atlantic Ocean. The circular system hovering over Bermuda jostled Irma onto northern Cuba Saturday, where being over land sapped it of some power, and then around the tip of the Florida peninsula, cutting down on storm surge damage on both coasts of the state.

“The Bermuda High is finite and it has an edge, which was right over Key West,” Masters said. Irma caught the edge and turned north.

For 10 days, computer-forecast models had struggled with how the high was going to push Irma around and when it was going to stop, said Peter Sousounis, director of meteorology at AIR Worldwide. “I have never watched a forecast more carefully than Irma. I was very surprised not by how one model was going back and forth -- but by how all the models were going back and forth.”...MUCH MORE

Or, as noted in the outro from "To Understand Finance, Embrace Complexity":
We last touched on complexity in Wednesday's "The Joy of Randomness: Central Bank Strategy, Management Technique and Stock Selection":
...Ya see, ya got your complex systems and ya got your chaotic systems and then ya got your complex-chaotic systems like weather or the economy or the stock market and when you endeavor at those levels of sophistication you realize:
"Nobody knows anything"
-William Goldman 

Complex systems are not to be confused with "the Caulk/Putty/Grout Complex" which was a post on trading the energy-efficiency aspects of the stimulus and is, actually, a different meaning of the word "complex".
And yes, contrary to the quote above, some people do know something, it's just that it is damn hard making money off it....