Storm seasons’ average figures going up
The average number of named storms and hurricanes per year in the Atlantic has increased, a federal agency announced Friday, setting a new baseline for how the hurricane seasons that Houstonians are so familiar with will be evaluated over the next decade.
Every 10 years, the Climate Prediction Center calculates new Atlantic storm season averages based on a 30-year period of record. The new average, drawn from data between 1991 and 2020, is 14 named storms, seven hurricanes and three major hurricanes of Category 3 or higher.
The previous average, based on the period from 1981 to 2010, was 12 named storms, six hurricanes and three major hurricanes.
“These updated averages better reflect our collective experience of the past 10 years, which included some very active hurricane seasons,” Matt Rosencrans, seasonal hurricane forecaster at the Climate Prediction Center, said in a news release. The center is part of the National Oceanic and Atmospheric Administration.
News of the higher average did not surprise local meteorologists who lived through last year’s record season of 30 named storms.
That season was so busy that storms had to be named using the Greek alphabet.
“It really just codifies everything that we kind of knew,” said Matt Lanza, who co-writes Space City Weather, a popular weather blog in Houston. “There’s been an uptick in storms, an uptick in hurricanes.”
NOAA offered several possible explanations for the increase, including new technology that has improved the agency’s ability to detect storms. NOAA also began naming what are known as “subtropical storms” only in 2002.
The Atlantic, too, has been more active since about 1995 because sea surface temperatures are in a warm phase. The temperatures for at least 1,000 years have moved between cool and warm phases that last decades.
How climate change factors in is still being studied: Stronger hurricanes are expected to be more likely. But how the overall number of storms will change is not well understood, said Robert Korty, an associate professor of atmospheric sciences at Texas A&M.
“It’s not actually clear what will happen to the total number of storms,” Korty said. “I think that remains one of the fundamental questions that we’d like to know more about in the tropics: What controls the count?”
Lanza said the way the last four or five hurricane seasons have gone, he finds himself bracing for the next one.
He said his baseline expectation is for a busy season.
The update in averages, after all, was just the latest in a string of changes that agencies have made ahead of this year’s season. NOAA’s regular tropical weather outlooks are going to start earlier than usual because of an increase in tropical cyclone activity in late May.
Also, the World Meteorological Organization said it would develop a second list of A-Z storm names to use after the first set is exhausted, instead of moving to the Greek alphabet, which has happened only twice.
No matter how many storms there are, it was always important to be prepared, said Jeff Lindner, meteorologist for the Harris County Flood Control District. This region could just as well be hit hard during an active season, or a less active one.
Noted Lindner: “It only takes one storm.”