This hurricane season could see even more storms than first expected, NOAA says

Just a few weeks shy of the peak of hurricane season, NOAA released an updated prediction for the number of storms to expect this year — and it’s a bit higher.

The latest prediction calls for 15 to 21 named storms, an uptick from the May update that called for 13 to 20 named storms. NOAA’s prediction for the number of hurricanes (7 to 10) and major hurricanes (3 to 5) didn’t change.

The record-breaking 2020 season saw 30 named storms, 14 of which were hurricanes and 7 of which were major hurricanes.

Matthew Rosencrans, the hurricane season outlook lead at NOAA’s Climate Prediction Center, told reporters on Wednesday that the prediction accounts for the season’s five named storms so far, including Elsa, which became the earliest fifth named storm on record.

The Atlantic’s peaceful month was shattered this week. The National Hurricane Center is now tracking three separate disturbances, all with a low chance of strengthening anytime soon.

Now there are two. Hurricane center watching disturbances in the far eastern Atlantic

“We’re already ahead of schedule,” Rosencrans said. “The quiet period time just brought us a little closer to normal.”

If 21 named storms do form, it would use up every name on the list. Rosencrans said there’s about a 15% chance that we see more storms than that and meteorologists would be forced to switch to the backup list of storm names, a new development after last year’s chaotic foray into the Greek alphabet.

One factor that could nudge the storm count toward the higher end of the range is the formation of a La Niña, an atmospheric phenomenon that leads to reduced wind shear in the Atlantic and better conditions for storms to form. NOAA recently issued a “La Niña watch” and said there’s a 45% chance the phenomenon could form from August to October, the peak of the season.

“If a La Niña does develop later in the season … that did play a role in keeping our storm numbers one or two higher,” Rosencrans said.

Wind shear, which eats away at a storm’s organization, has also been lower this year, and the west African monsoon season has been more active than usual. Both of these factors could hint toward a more active season, especially over the backdrop of the warm phase of the Atlantic Multi-Decadal Oscillation, a weather phenomenon ongoing since 1995 that has favored more storm activity.

However, Rosencrans said, a cooler ocean could keep the 2021 season from reaching its predicted peaks. Sea surface temperatures have been about average so far this season, as opposed to the above-average temperatures recorded last year.

It’s hard to note climate change’s footprint on a specific hurricane season, especially before it’s really gotten started, but scientists are confident that global warming is leading to more powerful and wetter storms, and sea level rise is leading to more storm surge.

“Wind speeds are on average about 10% higher and that’s because we have more Category 4s and 5s,” Rosencrans said. “Another impact is when storms do form and they make landfall, they are able to create more rainfall, about 3% more in any storm.”