Hurricane Beryl Passes Cayman Islands on Way to Mexico: Live Updates

Rick Spinrad, the NOAA administrator, said at a news conference on Thursday morning that the agency’s forecasters believed eight to 13 of the named storms could become hurricanes, meaning they would include winds of at least 74 miles per hour. Those could include four to seven major hurricanes — Category 3 or higher — with winds of at least 111 m.p.h.

According to NOAA, there is an 85 percent chance of an above-normal season and a 10 percent chance of a near-normal season, with a 5 percent chance of a below-normal season. An average Atlantic hurricane season has 14 named storms, including seven hurricanes and three major hurricanes.

While it only takes one storm in a below-average season to devastate a community, having conditions conducive to almost twice the average amount of storms makes it more likely that North America will experience a tropical storm or, worse, a major hurricane.

There are 21 entries on this year’s official list of storm names, from Alberto to William. If that list is exhausted, the National Weather Service moves on to an alternative list of names, something it’s only had to do twice in its history.

NOAA typically issues a May forecast and then an updated forecast in August. Before Thursday, NOAA’s most significant May forecast was in 2010, when it forecast 14 to 23 named storms; that year, 19 ultimately formed before the end of the season. In 2020, the May forecast was for 13 to 19 named storms, but an updated forecast for August was even higher, with 19 to 25 named storms. That season ultimately saw 30 named storms.

The hurricane outlooks this year have been notably aggressive because of the unprecedented conditions expected.

As forecasters look toward the official start of the season on June 1, they see combined circumstances that have never occurred in records dating to the mid-1800s: record warm water temperatures in the Atlantic and the potential formation of La Niña weather pattern.

Brian McNoldy, a researcher at the University of Miami who specializes in hurricane formation, said that without a previous example involving such conditions, forecasters trying to predict the season ahead could only extrapolate from previous outliers.

Experts are concerned by warm ocean temperatures.

“I think all systems are go for a hyperactive season,” said Phil Klotzbach, an expert in seasonal hurricane forecasts at Colorado State University.

The critical area of the Atlantic Ocean where hurricanes form is already abnormally warm just ahead of the start of the season. Benjamin Kirtman, a professor of atmospheric sciences at the University of Miami, earlier described the conditions as “unprecedented,” “alarming” and an “out-of-bounds anomaly.”

Over the past century, those temperatures have increased gradually. But last year, with an intensity that unnerved climate scientists, the waters warmed even more rapidly in a region of the Atlantic where most hurricanes form. This region, from West Africa to Central America, is hotter this year than it was before the start of last year’s hurricane season, which produced 20 named storms.

The current temperatures in the Atlantic are concerning because they mean the ocean is poised to provide additional fuel to any storm that forms. Even if the surface suddenly cools, the temperatures below the surface, which are also remarkably above average, are expected to reheat the surface temperatures rapidly.

These warmer temperatures can give energy to the formation of storms — and help sustain them. Sometimes, if no other atmospheric conditions hinder a storm’s growth, they can intensify more rapidly than usual, jumping hurricane categories in less than a day.

Combined with the rapidly subsiding El Niño weather pattern in early May, the temperatures are leading to mounting confidence among forecasting experts that there will be an exceptionally high number of storms this hurricane season.

A parting El Niño and a likely La Niña are increasing confidence in the forecasts.

El Niño is caused by changing ocean temperatures in the Pacific and affects weather patterns globally. When it is strong, it typically thwarts the development and growth of storms. Last year, the warm ocean temperatures in the Atlantic blunted El Niño’s effect to do that. If El Niño subsides, as forecasters expect, there won’t be much to blunt the season this time.

Forecasters specializing in the ebbs and flows of El Niño, including Michelle L’Heureux with the National Weather Service’s Climate Prediction Center, are pretty confident not only that El Niño will subside but that there is a high likelihood — 77 percent — that La Niña will form during the peak of hurricane season.

The system could throw a curve ball, she said, but at this point in the spring, things are evolving as forecasters have anticipated. A La Niña weather pattern would already have them looking toward an above-average year. The possibility of a La Niña, combined with record sea surface temperatures this hurricane season, is expected to create a robust environment this year for storms to form and intensify.