A shift to El Niño could mean lighter hurricane season, CSU forecast says
The 2023 hurricane season is forecast to produce fewer storms than in recent years, but Florida and the rest of the U.S. East Coast should still be prepared for a strike, according to a report from Colorado State University.
The annual forecast authored by CSU expert Dr. Phil Klotzbach is one of the most anticipated ahead of the official start of the six-month tropical weather season that runs from June 1 to Nov. 30. It began 40 years ago by now-retired professor William Gray.
“A lot of questions about what’s going to happen in 2023, and the word you’re going to hear a lot in this talk is uncertainty,” said Klotzbach on Thursday during the National Tropical Weather Conference in South Padre Island, Texas. He cited competing models that foresee warmer Atlantic waters, which could mean more activity, vs. a likely shift to El Niño conditions later this year, which could hamper tropical development.
That leads to what is a slightly below average forecast, expecting 13 named systems with six becoming hurricanes, he said. Of those six, two are forecast to become major hurricanes, either a Category 3, 4 or 5 with at least 111 mph sustained winds.
That falls a little below what the National Oceanic and Atmospheric Administration now deems as average over the past three decades of 14 named storms, of which seven are hurricanes and three are major ones.
Last year’s season, which had both Hurricane Ian and Nicole striking Florida, was around that average with 14 named storms, eight hurricanes and two major hurricanes. That was much less storm activity than the record-breaking 2020 season that saw 30 storms, and the 21 storms that formed in 2021.
The report says there is a near-average chance for major hurricanes to make landfall along the continental United States coast and the Caribbean. The report cites a 44% chance of U.S. coastal landfall, 22% for the U.S. East Coast, including the Florida peninsula, 28% for a Gulf Coast landfall from the Florida Panhandle west to the Texas-Mexico border and 49% chance for a Caribbean landfall.
“As is the case with all hurricane seasons, coastal residents are reminded that it only takes one hurricane making landfall to make it an active season for them,” the report states. “They should prepare the same for every season, regardless of how much activity is predicted.”
The report cites a shift from the weather phenomenon known as La Niña from the last few years into El Niño by the latter half of the hurricane season, including what is traditionally the height of activity from August to October.
The two are part of a global pattern known as the El Niño-Southern Oscillation cycle, or ENSO, according to the NOAA. The cycle looks at the changes in temperatures between the ocean and atmosphere in the east-central Equatorial Pacific.
An ENSO cycle is made up of three phases: a neutral phase, a warm phase (El Niño) and a cold phase (La Niña.)
With warmer temperatures in the Pacific, more vertical wind shear can be expected in the Atlantic hurricane basin, which basically blows apart tropical activity from the skies above as it tries to form.
That leads to fewer tropical storms and hurricanes in the Atlantic.
But the eastern and central tropical and subtropical Atlantic is already much warmer than normal, Klotzbach said.
Because of the increased warmth, there is a greater chance for hurricane activity, even though El Niño could tamp down the season before November.
