Near-record ocean temperatures and a strengthening La Niña could spell trouble for the East Coast of the United States, with federal forecasters warning of an 85% chance of above-normal Atlantic hurricane activity this year and predicting up to 25 named storms.
“All the ingredients are definitely in place to have an active season,” Ken Graham, director of the National Weather Service, said during a briefing this week. “It is cause for concern, of course, but not alarm. “We need to take advantage of this time to really be prepared for hurricane season.”
But conditions on the West Coast may be calmer than last year, when a rare storm swirled off the coast of Baja California before making landfall in early August. When he arrived in southern California, Hurricane Hilary had been downgraded to a post-tropical minimum, but still caused some devastation.
In Mexico, Hilary damaged or destroyed at least 87 homes when she dropped more than a foot of rain on parts of northern Baja California Sur. The storm also prompted the first tropical storm watches and warnings issued in Southern California, where it broke several daily rainfall records, washed out roads, damaged homes, and caused widespread power outages, among other issues.
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The good news is that the outlook for this season looks calmer for California and the West. The forecast for the eastern Pacific hurricane season indicates a 60% chance of below-normal storm activity, according to the National Oceanic and Atmospheric Administration.
This includes an estimated 11 to 17 named storms, and four to nine of those storms became hurricanes. Between one and four of them could become major hurricanes (categories 3, 4 or 5) with winds of 111 mph or higher.
The numbers are below normal for the eastern Pacific basin, which typically averages 15 named storms and eight hurricanes in a season. The active 2023 eastern Pacific hurricane season saw 17 named storms, including Hilary and nine other hurricanes.
NOAA officials said the more optimistic outlook is partly due to the expected development of La Niña later this year.
The weather pattern in the tropical Pacific is associated with colder, drier conditions in Southern California and is a major driver of weather patterns around the world. The chances of storms occurring in the eastern Pacific are much greater when its counterpart, El Niño, is present, as was the case when Hilary struck last year.
But El Niño is waning and a transition to neutral conditions is likely in the coming weeks. There is a 49% chance that La Niña will develop in June or August, and a 69% chance that it will develop between July and September, according to NOAA.
That means their California counterparts on the East Coast may not fare as well. As many as 13 of the 25 expected named storms are forecast to become hurricanes with winds of 74 mph or greater. Four to seven of them could be major hurricanes.
“This season looks extraordinary in several ways, based on our data and models, with El Niño/La Niña playing an important role,” said NOAA Administrator Rick Spinrad. “The key this year, like any year, is to prepare and stay prepared.”
Officials attributed the stormy Atlantic outlook to a confluence of factors including record ocean temperatures; reduction of Atlantic trade winds and wind shear; and the development of La Niña.
Ocean temperatures have been boiling for months as the planet continues its streak of record heat. In July, temperatures off the coast of Florida soared to 101 degrees, the temperature of a hot tub. That ocean heat creates more energy to drive storm development in the Atlantic, Spinrad said.
“We know that warm sea surface temperatures are a major factor in the rapid intensification of tropical cyclones into major hurricanes,” he said.
La Niña also tilts the odds toward hurricane activity in the Atlantic because it tends to reduce wind shear in the tropics. Light winds allow hurricanes to grow in strength and also minimize cooling of the oceans.
“You really look at all of these, all the different patterns, and they all come together to make this big forecast,” Graham said. “I've seen strong storms hit warm waters only to be weakened by shear.”
Cathedral City residents shovel deep mud from a residential road following Hilary in August.
(Mario Tama/Getty Images)
He and other officials noted that hurricanes and their associated winds, flooding and storm surge can produce damage that affects residents and local economies for months or even years after a storm has passed.
Although most of last season's activity occurred off the coast of the United States, Atlantic tropical cyclones caused approximately $4 billion in damage. That figure increases to almost $5 billion if the impacts of Hurricane Hilary are added.
“The impacts can go far beyond the actual impact of the storm,” Erik A. Hooks, deputy director of the Federal Emergency Management Agency, said during the briefing. “These storms, like Hurricanes Ida and Hilary, can have significant impacts hundreds of miles inland.”
By the end of her career, Hilary had contributed to more than $900 million in damages in the United States and Mexico and at least three deaths. The storm caused debris flows in San Bernardino County, collapsed roads in Death Valley and flooded communities in the Coachella Valley.
Hooks urged people to develop a clear understanding of their own unique risks, such as medications that require refrigeration or medical devices that require electricity, before storm season begins, and to have a plan in place.
“Now is the time to ask these questions,” he said. “It's about anticipating risks, taking steps to mitigate them and acting, which in turn helps drive recovery after the emergency passes.”
The eastern Pacific hurricane season runs from May 15 to November 30, with peak activity typically occurring between July and September. The official start of the Atlantic hurricane season begins on June 1.
