The Pacific Ocean has been having a busy hurricane season, with Trudy this week becoming the latest storm to roll off what seems to be an endless conveyor belt of tropical cyclones across the region.
Closest to North America, meteorologists divide the Pacific into two regions, central and eastern, and Trudy is the 21st named storm to form between them this year. It is forecast to move toward Mexico’s western coast this week, and like several of its predecessors, Hurricane Trudy is expected to rapidly intensify, possibly becoming as strong as a Category 4 storm along the way.
Whether it makes landfall remained uncertain on Thursday. Regardless, the Pacific’s relentless run of storms has already made this a remarkable year.
Here’s how unusual the season has been so far.
It’s had more of the strongest hurricanes.
Meteorologists call hurricanes that reach Category 3 or above “major.” If Trudy were to reach that intensity — and forecasters expect that it will — it would be the 10th major hurricane in the Pacific this year.
In a typical season, only about four or five Pacific hurricanes get that strong, according to the National Oceanic and Atmospheric Administration.
The record in the Pacific is 11, said Phil Klotzbach, a senior research scientist in the department of atmospheric science at Colorado State University. It was set in 2015, which, like this year, was influenced by a strong El Niño. One of the calling cards of El Niño is a more active hurricane season in the Pacific, where the weather pattern heats up the ocean and provides fuel for more storms, and a comparatively quiet one in the Atlantic.
Some of this year’s strongest storms, like the Category 5 Hurricane Genevieve, stayed well over open waters. Others, like Hurricanes Lala and Lowell, came dangerously close to Hawaii, bringing significant rain and strong winds. Western Mexico has been battered repeatedly as storms crawled along its coastline, some making landfall and some dropping heavy rain before veering away.
With around six weeks until the season ends on Nov. 30, and El Niño conditions continuing to grow stronger, there is still time for that tally to climb and potentially set a record.
More of them have intensified especially fast.
The 2015 season also set a record for the number of Pacific storms to undergo what meteorologists call “rapid intensification,” with 13 storms doing so. Rapid intensification occurs when a storm’s maximum sustained wind speed increases by at least 35 miles per hour within 24 hours. That’s about two categories on the Saffir-Simpson Hurricane Wind Scale.
Among those 13 storms in 2015 was Hurricane Patricia, which underwent one of the fastest and most explosive intensifications ever recorded in a tropical cyclone, with its wind speeds increasing by 120 miles per hour. It remains one of the strongest storms ever in the Western Hemisphere, though Hurricane Polo came close last month.
So far this year, nine of the storms in the Pacific have rapidly intensified, said Mr. Klotzbach, well above a typical season’s count.
That, too, can be traced to El Niño, which, he said, “has led to both a dynamic and thermodynamic environment that is extremely conducive for tropical cyclones to form and intensify.”
The season has set a few records already.
The number of storms tells only part of the story. Another measure is the accumulated cyclone energy, or ACE, a measurement of the total wind energy of tropical storms and hurricanes across the season. The measurement takes into account the storms’ intensity and duration, so a season with bigger storms that last longer will rank higher.
By that measure, the Pacific has already entered record territory.
On Thursday, the ACE reached 331.1, higher than ever before in the Pacific, Mr. Klotzbach said. Almost half of that total came from three: Lowell, Nolo and Polo.
The previous record was 318.1, set in 2018.
Trudy and Simon, which by Thursday was a tropical storm but at one point had grown into a powerful Category 4 storm, are forecast to generate another 25 ACE in the next few days, Mr. Klotzbach added.
The Pacific has also set a record for the number of individual hurricane days. Each day a storm is spinning counts as a day. So far, there have been 70.25 days this year, according to records kept by Mr. Klotzbach and his researchers at Colorado State, surpassing the 68.25-day record for 2018. (In comparison, the Atlantic, which is having a historically quiet year, had two hurricane days so far this year.)
Thanks to extremely warm ocean waters and low wind shear, conditions remain favorable for further storms to form before the season ends.
And there may not be long to wait for the next one.
“There is considerable model signal for another tropical cyclone forming off the west coast of Mexico later next week,” Mr. Klotzbach said.
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