The science of predicting tropical storms and hurricanes has improved greatly in recent years, but it still isn’t exact. That’s why storm maps show not a straight-line path of a hurricane’s progress but a tadpole-shaped “cone of uncertainty.” The area inside the cone is the danger zone, and the size of each circle within it “is set so that two-thirds of historical official forecast errors over a 5-year sample fall within the circle,” according to a National Hurricane Center explanation.
The cone of uncertainty was in the news last week as Hurricane Dorian, a Category 5 storm, bore down on the southeastern United States after devastating the Bahamas. On September 1, President Trump tweeted that “in addition to Florida - South Carolina, North Carolina, Georgia, and Alabama, will most likely be hit (much) harder than anticipated.” Whoops. Alabama had never been included in the forecast, or positioned within many miles of the cone of uncertainty. Trump apparently invented the “prediction.”
The National Weather Service in Birmingham, Alabama, immediately reassured Alabamians that their state would “NOT see any impacts from #Dorian.” The NWS, as its name indicates, is an agency of the federal government. Nevertheless, Trump would not be contradicted. In a move that could have been dictated by Stalin, or Orwell, he made up his own alternative weather facts, and a map to support them.
On September 4, President Trump displayed a doctored National Hurricane Center map dated August 29 that depicts Hurricane Dorian’s cone of uncertainty along with a bulbous black-outlined annex of uncertain origin and dubious credibility. Source: Politico