We’re currently in the middle of the largest U.S. hurricane lull since 1850 — but we’re also still having strong global hurricane seasons. What explains this seeming paradox? Simple. It’s statistics.
NASA scientist Timothy Hall and researcher Kelly Hereid ran a series of statistical models, and using those, calculated that a lull of this size — where no storm Category 3 or larger manages to hit land — should be expected to occur in the U.S. every 177 years, putting us squarely in the statistical center.
So, does this mean we’re due for a tough year in the next coming season, or the one after? Not so much, Hall explained to NASA. In fact, we’re pretty much exactly where we are every year:
Think of it this way: If you flip a coin and it comes up heads nine times in a row, there is still a 50-50 chance that the 10th flip will come up tails. Hall and Hereid’s statistical analysis found that in any given year there is a 39 percent probability of one or more major hurricane landfalls on the U.S and that that probability does not depend on the drought length. So what are the chances of this historic period coming to an end in 2015, based solely on the odds of the historical record? Thirty-nine percent, Hall said. “Each year is roughly independent of the year before,” Hall said. “There are known signals, and natural cycles, and possibly human-induced influences. But for the most part, they are independent, especially for the rare intense landfalls.”
The study was published in Geophysical Research Letters.
Top image: Timelapse of Hurricane Andrew in 1992 as it moves inland /F. Hasler, M. Jentoft-Nilsen, H. Pierce, K. Palaniappan, and M. Manyin. NASA