Hurricane Hilary could be part of a trend, study says
A satellite traced the path of an atmospheric river flowing across the northern Pacific Ocean. Enhanced imagery shows mid-level tropospheric water vapor. (National Oceanic and Atmospheric Administration image)
As climate change heats up the ocean, unusual Pacific storms like Hurricane Hilary and flooding summer rains could be a peek into the future of the West Coast.
Global sea surface temperatures reached record highs in 2022, with parts of the Pacific Ocean and the Gulf of Mexico all engulfed in abnormally intense and persistent marine heat waves, according to an annual review of the global climate.
The State of the Climate report, compiled by the National Centers for Environmental Information at the U.S. National Oceanic and Atmospheric Administration, is based on contributions from more than 570 scientists in over 60 countries.
It provides the most comprehensive update on Earth’s climate indicators, notable weather events and other data collected by environmental monitoring stations and instruments located on land, water, ice and in space.
According to the report, Earth’s greenhouse gas concentrations were the highest on record in 2022, contributing to warming trends across the globe.
The eastern North Pacific—which extends from Central America to Canada—was the only basin with more hurricanes, typhoons, and cyclones than normal in 2022. Those storms were also more intense than typical, as the eastern North Pacific had an above-normal number of named storms, according to the report.
Researchers noted that tropical storm Bonnie was the first cyclone to survive the crossover from the Atlantic Ocean to the Pacific Ocean since Hurricane Otto in 2016, and intensified into a major hurricane over the eastern North Pacific.
Hurricane Julia also crossed over from the Atlantic to the eastern North Pacific while maintaining at least tropical storm-force winds. No prior year on record has observed two systems that crossed over Central America while maintaining at least tropical-storm intensity.
Those climate extremes continued into 2023, when Hurricane Hilary resulted in the first-ever tropical storm watch for Southern California.
Hilary continued northward into Southern Nevada as a sub-tropical storm, where it caused intense floods and structural damage in many parts of Clark County, including to the Timbisha Shoshone Tribe reservation on the California-Nevada border.
“Here in the village itself some of the roads got damaged,” said Mandi Campbell, the historic preservation officer for the tribe. And not only roads, but homes too.
Tropical storms need warm water to survive and months of much warmer sea surface temperatures in the eastern Pacific helped the storm develop and stay intact, said Dan McEvoy, an associate research professor and regional climatologist for the Desert Research Institute.
“All across the eastern Pacific the sea temperatures are well above average right now. That makes it easier for any storm that does form to strengthen quicker and intensify to become a stronger storm,” McEvoy said. “That’s the clearest link between climate change and the likelihood of more storms being able to develop in the Pacific Ocean.”
An oceanic and atmospheric phenomenon, known as La Niña, also exacerbated drought conditions in the southwest United States, leading to more intense floods and landslides when extreme precipitation occurred over dry land, according to the report.
While the report notes some effects of rising sea temperatures on the western United States, researchers say a lack of data on rare tropical cyclones in the region leaves a lot of uncertainty about how a warmer Eastern Pacific will impact the region.
“It’s not super clear,” McEvoy said.
The National Hurricane Center doesn’t issue seasonal projections for the Eastern Pacific, like the closely watched Atlantic hurricane season forecast.
East Pacific hurricanes generally form off the coast of Mexico and often head west, away from land, losing strength as they travel over cooler water. Some curve back toward the east and make landfalls along the west coast of Mexico, but having a major hurricane barreling north toward California is exceedingly rare.
A 2017 study by climate scientists did find links between global warming and extreme Pacific hurricane activity in 2015, but noted that more research is needed.
The data climate scientists do have shows that global sea temperatures are on the rise, and have had pronounced effects on all seven continents.
According to the report, 2022 was the warmest La Niña year on record, surpassing the previous record set in 2021.
Ocean heat and global sea level in 2022 were the highest on record. Approximately 58% of the ocean surface experienced at least one marine heatwave in 2022, which is defined as at least five consecutive days of sea-surface temperatures in the top 10% of warmest surface temperatures on record.
The Arctic had its fifth-warmest year in the 123-year record. It was the ninth-consecutive year that the Arctic warmed more quickly than the rest of the planet.
With the re-emergence of El Niño in 2023, globally-averaged temperatures this year are expected to exceed those observed in 2022, according to the State of the Climate report. The southwest is likely to follow that trend.
“One thing we should expect is that it will likely be warmer this winter than last winter, as El Niño ramps up. But outside of that, in terms of precipitation or snow patterns across the West for the winter, there’s still a lot of uncertainty.”
The State of the Climate report is a peer-reviewed series published annually as a special supplement to the Bulletin of the American Meteorological Society. The journal makes the full report openly available online.
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