By: John Donovan, How Stuff Works
Predicting 2018's Storms
Colorado State's team is predicting seven hurricanes in 2018: slightly above-average, sure, but that would be much better than that outlier of 2017.
CSU, of course, is not the only one in the hurricane predictions game. University College of London has a group, Tropical Storm Risk, that predicts storms every year, too. (That group is calling for a decrease in Atlantic hurricane activity this year, about 15 percent lower than a long-term norm and about 25 percent lower than the norm for the past 10 years.)
The National Oceanic and Atmospheric Association's Climate Prediction Center (the NOAA's CPC) will come out with its call, too, in May. The Weather Company, an IBM unit that includes The Weather Channel, releases its predictions on April 24. The season runs through November.
James Belanger, the senior meteorological scientist at The Weather Company, explains how his team comes to its annual hurricane forecast. "We have some in-house analytics and capabilities that we look at. And then there's also kind of this human element," Belanger says. "A lot of times you might have a statistical model that provides you a baseline guidance. We look at a variety of statistical models and long-range weather forecasts - season forecasts that go out seven months - and we have access to some of those predictions. So, based on kind of a combination of that information, as well as what we're seeing in large-scale climate patterns, that's what we use to fine tune the numbers."
The differing ideas on the upcoming hurricane season demonstrate how complicated and inexact the science can be. Scientists all over the world gather information from more than 1,000 buoys, more than 3,000 ships, hundreds of weather balloons, several aircraft and a handful of satellites to track storms and measure things like water temperature, air pressure, winds and wind shear, just to name a few. They combine all that data with many other factors and compute it all through complex mathematical models (NOAA has a "Supercomputer System") to settle on its forecasts and predictions.
El Niño and La Niña
Ironically, some of the most important information the scientists rely on in predicting the Atlantic hurricane season isn't even taken from the Atlantic Ocean. Scientists lean heavily on measurements from El Niño and La Niña, a combined weather phenomenon in the central and east-central Pacific around the equator. (In the climate community, El Niño and La Niña also are known as ENSO, for El Niño/Southern Oscillation.)
El Niño is a water warming trend in the Pacific Ocean, especially those waters in the eastern Pacific, on the west side of Central America; La Niña is a cooling trend. The two are important because, generally, cooler water in the Pacific suggests warmer water in the Atlantic (and vice versa).
Monitoring the temperatures of the Pacific matters. Hurricanes are partly fueled by warmer water, so cooler water in the Pacific (a result of La Niña) generally means warmer water - and more hurricanes - in the Atlantic.
"When we're talking climate predictions, the Pacific tends to be the basin that has the most predictability," Belanger says. "We can make a prediction more skillfully in that region than anywhere else."