A moisture-laden atmospheric river is approaching the West Coast, but Lake Mead and Lake Powell might have to wait a little longer before they benefit from the winter storm.
After years of drought, the two lakes in Nevada, Arizona and Utah reached concerningly low levels in the summer of 2022. However, water levels have since started to recover because of above-average precipitation and snowpack that melted throughout this year. As of Friday morning, Lake Mead was at 1,064 feet, and Lake Powell was at 3,571 feet.
An incoming atmospheric river is forecast to saturate much of the Pacific Northwest over the next week but likely won't benefit either of the lakes until next spring after snowfall associated with the storm melts.
An atmospheric river is a "long, narrow region in the atmosphere—like rivers in the sky— that transport most of the water vapor outside of the tropics," according to the National Oceanic and Atmospheric Administration (NOAA). More than a dozen similar storms battered California last winter, and although the deluge alleviated much of the state's drought, it also wreaked havoc through flooding and mudslides.
The incoming storm will bring some snowfall to the Rocky Mountains, meaning that once spring arrives the reservoirs could benefit from the runoff.
"A little moisture will fall as snow across Utah and into the Colorado Rockies that would eventually melt off into Lake Mead and Lake Powell reservoirs," AccuWeather senior meteorologist Adam Douty told Newsweek.
Much of California also will escape the incoming atmospheric river, as the rain is forecast to pummel Oregon and Washington. Local forecast totals could reach up to 20 inches of rain in some places. Only the northeast corner of California will be saturated, with forecasters predicting up to 4 inches, and although the rain won't aid Lake Powell or Lake Mead, it might benefit Lake Shasta and Trinity Lake.
Lake Mead and Lake Powell are in a drastically improved position compared to this time last year when both reservoirs struggled with drought. Lake Mead water levels are 20 feet higher and Lake Powell's 40 feet higher than they were in December 2022.
AccuWeather senior meteorologist Dale Mohler previously told Newsweek that AccuWeather didn't forecast high precipitation for Lake Mead over the winter, while NOAA predicted the region would receive higher-than-average snowfall due to El Niño.
"Our winter forecast for Lake Mead is normal or below normal," Mohler said.
El Niño is one of two climate patterns that greatly impact the Earth's weather. La Niña recently culminated in the spring. El Niño started in June, and NOAA has identified it as having high odds of being historically strong.
Updated 12/1/23, 10:40 a.m. ET: This story was updated to include a comment from AccuWeather senior meteorologist Adam Douty.
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Anna Skinner is a Newsweek senior reporter based in Indianapolis. Her focus is reporting on the climate, environment and weather ... Read more
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