The Atlantic is acting up out of season. Again.
A disturbance near Bermuda is likely to become the first tropical storm of the Atlantic hurricane season in the next two days. As of Friday morning, the National Hurricane Center gave the weather system a 90% chance of becoming a named storm. (It would take the name “Ana,” the first name on NOAA’s alphabetic list of Atlantic storm names for 2021.)
Hurricane season starts June 1, so this storm is a little early. But if Tropical Storm Ana forms as the odds suggest, it would mark yet another preseason weirdo. The storm would likely peter out pretty quickly, with the NHC noting that the system is “forecast to move northeastward into a more hostile environment by Saturday night or Sunday.” So while would-be Ana is not a major threat, it would mark the seventh season in a row with a preseason storm.
That’s in part why the National Oceanic and Atmospheric Administration created a new policy in March of this year of issuing its tropical weather outlooks before hurricane season actually starts. Earlier storms aren’t necessarily more worrisome than later storms; in fact, storms that form later in the season tend to be stronger and more dangerous as the ocean reaches peak heat.
Earlier this year, the agency updated the “average” hurricane season as part of a regular 10-year tweak to incorporate new data. That update, which uses data from 1991-2020 to define average, called for more storms than the previous set of averages that ran from 1981 to 2010. With that new average in mind, NOAA predicted this week that we’re probably in for yet another above-average hurricane season. The agency’s scientists said Thursday that they expect between 13 to 20 named storms to form. Of those storms, the agency says it expects 6 to 10 to become hurricanes, and 3 to 5 of those could be major hurricanes, classified as Category 3 or higher.
Not exactly great news, but at least the 2021 Atlantic hurricane season isn’t likely to be as active as 2020, which saw a record-breaking 30 named storms, 12 of those which made landfall. There were so many storms that the agency ran through the alphabet for its naming convention—only the second time that’s happened—and had to start using Greek letters.
Climate change is influencing storms by heating up the ocean, which gives them the fuel they need to ramp up, as well as boosting storm surge thanks to sea level rise. Some research has shown that storms such as record-setting Hurricane Harvey also got a rainfall boost from climate change. Experts have also noted that more sophisticated technology has allowed scientists us to more closely monitor what’s going on out in the ocean and catch storms that might have evaded detection in the pre-satellite era, so it’s not all on climate change. Still, the fingerprints are definitely there.
“We’re seeing a rise in the proportion of hurricanes that reach major hurricane status, Category 3 and above,” Kerry Emanuel, a climate expert at the Massachusetts Institute of Technology, told the New York Times. “That’s what we’re unequivocally seeing in the satellite data.”