LAUSR

& ON THE MORNING of September 1, 2019, during the days when people in the Southeastern coast of the United States were preparing for the likely impact of hurricane Dorian, President Donald J. Trump sent a puzzling tweet. Trump wrote that “In addition to Florida––South Carolina, North Carolina, Georgia, and Alabama, will most likely be hit (much) harder than anticipated.” The problem was that the National Hurricane Center’s (NHC) forecast map issued a few hours earlier the same morning, at 5 AM, had the cone of uncertainty quite far from Alabama [see Figure 1]. The President’s tweet caused alarm among Alabamians;many of them, feeling confused andworried began calling the Birmingham office of the NHC, forcing it to tweet a correction: “Alabama will NOT see any impacts from #Dorian. We repeat, no impacts from Hurricane Dorian will be felt across Alabama. The systemwill remain too far east.” Mentioning Alabama in the tweet was certainly a mistake. There is always a 30% chance that the position of a hurricane center will end up outside of the NHC’s cone of uncertainty at some point, but in the morning of September 1, the chances of Dorian’s hitting Alabama “harder than anticipated” in the following days were negligible. The Westernmost boundary of the cone was very far from Alabama’s Southeastern tip. Even so, President Trump refused to issue a correction or apology. Instead, he repeatedly doubled-down. In a White House briefing on September 4th, he tried to prove that there was Digital Object Identifier 10.1109/MCG.2019.2961716