How climate change contributes to the atmospheric river slamming the West Coast
The bomb cyclone in the Pacific Northwest is about to pull in a plume of moisture in the form of an atmospheric river.
Atmospheric rivers are essentially rivers in the sky that collect moisture from tropical areas and redistribute the water to higher latitudes. The storm is forecast to hit the West Coast from the San Francisco Bay Area to just south of Portland, Oregon, starting Tuesday night and lasting until Friday.
The current bomb cyclone impacting Northern California to Washington state has brought wind gusts up to 84 mph. A significant amount of damage has been reported along the Pacific Northwest I-5 urban corridor, and more than 700,000 customers were without power on Tuesday morning. The storm exploded into a bomb cyclone near Vancouver Island, Canada, where winds gusted near 101 mph.
As the storm sits and spins over the ocean for the next couple of days, it will help to push a plume of Pacific moisture -- the atmospheric river -- into Oregon and northern California, forecasts show.
Numerous flood, snow, avalanche and high wind alerts have been issued for the West Coast through Friday. The National Weather Service has issued a flood watch for northern California, where flooding is possible over the next 24 to 48 hours.
Atmospheric rivers are influenced by a multitude of weather and climate factors, and the impacts they bring can vary greatly from one event to another, according to scientists.
While it is not possible to determine the specific influence that human-amplified climate change may have had on an event as it unfolds, research shows that climate change is making the impacts from many naturally occurring events, like atmospheric rivers, more intense.
There are many variables involved when linking atmospheric river events to climate change. Earlier this year, another major variable that was in place was El Niño. Some experts caution that more research is needed before the link between climate change and atmospheric rivers can be more specific and with higher certainty.
Julie Kalansky, a climate scientist and deputy director of operations at the Center for Western Weather and Water Extremes at the University of California, San Diego's Scripps Institution of Oceanography, told ABC News that while there is still a lot to learn about the potential links between atmospheric rivers, climate change, and El Niño, broader connections can be made to the extreme impacts that certain events bring.
"More of [California's] precipitation, so rain and snowfall, will be coming from atmospheric rivers, according to the model projections," Kalansky said.
In a warming climate, more winter precipitation will fall as rain instead of snow, and the winter season will experience larger increases in extreme precipitation events since winter is the season experiencing the greatest overall warming, according to the Fifth National Climate Assessment, released in late 2023.
The report found that the effects of climate change were worsening in every part of the U.S.
Experts say that this shift in precipitation type could be accompanied by more frequent and intense extreme rainfall events, adding that atmospheric rivers have the potential to cause more extreme precipitation events in the future.
As global temperatures continue to warm, it allows the atmosphere to hold more moisture, causing rainfall events to become more frequent and extreme, according to recent research by the National Oceanic and Atmospheric Administration
More intense extreme rain events also increase the frequency and scale of flash flooding, as the influx of water is more than current infrastructure was built to handle.
In the continental U.S., California already experiences the most year-to-year variability wet and dry conditions, Kalansky told ABC News. Southern California has an even more variable climate than Northern California, even without the current El Niño event in place, which is also contributing heavily to the excessive moisture in recent weeks.
"Climate projections show that the variability between wet and dry is projected to become even more variable in the future, said Kalansky.
In states like California, the latest research shows that human-amplified climate change could produce less frequent, but more intense precipitation events. Wild swings, for example, from a devastating drought to record-breaking precipitation will become more common and extreme in the coming years, which could also lead to more destructive impacts, according to the California Climate Adaptation Strategy.
ABC News' Max Golembo contributed to this report.
