El Niño may bring warmer, wetter winter – and big Colorado River basin snowpacks

For the next three months, climate scientists say Nevada can expect warmer winter temperatures and above average rain.

Unusually warm waters in the eastern Pacific Ocean this year have created an El Niño weather pattern  that can generate more storms and above-average precipitation across the Southwest.

For Nevada, that could mean warmer temperatures during the winter months and extra precipitation. El Niño winters also often bring extra snow in the mountainous regions of the West, like the Sierra Nevada mountain in California and the southern part of the Rocky Mountains.

It’s been four years since the last El Niño event, after three consecutive La Niña winters, a rare phenomenon called a “triple-dip.”

Since earlier this year, climate scientists have warned about the possibility of a “moderate to strong” El Niño winter after its long absence. And the stronger the El Niño event, the more likely it will spur climate extremes, often with catastrophic consequences.

This year’s El Niño event is still developing, but it’s shaping up to be a long one. It’s almost certain El Niño will last through most of winter, and a 90% or higher chance it lasts into spring, according to the Climate Prediction Center, a division of the National Weather Service. 

Climate scientists caution that while El Niño does nudge the odds towards certain climate outcomes, it never ensures them. 

Mid-November temperatures in Nevada resulting from El Niño will likely be above average, before dipping to below average temperatures later in the month, according to the latest National Weather Service data. 

Climate scientists at the National Weather Service are also predicting a slightly higher likelihood of above average rain in Nevada in coming weeks.

From December through February, the National Oceanic and Atmospheric Administration said wetter-than-average conditions are most likely across parts of California and Nevada, as well as the South and Southeast.

During those months, NOAA said there’s a 50% chance eastern and western Nevada will experience above average precipitation, and a 40% chance of above average precipitation throughout the rest of the state. 

If those predictions hold true, drought conditions in Nevada will continue to improve, making almost the entire state drought free. However, drought conditions are likely to persist in portions of Southern Nevada even under favorable conditions, according to NOAA.

Still, “El Niño with its enhanced precipitation is expected to provide drought relief to the southern U.S. during the next few months,” said Brad Pugh, operational drought lead with NOAA’s Climate Prediction Center in the winter outlook report.

Nevada is also most likely set to experience warmer-than-average temperatures this winter, with northwestern Nevada facing the greatest odds of experiencing above average temperatures.

The biggest question for Nevada is how El Niño will affect the Colorado River basin snowpack this winter, a vital source of water for the state in the summer.

The NOAA winter outlook report does not project seasonal snowfall accumulations, because snow forecasts are generally not predictable more than a week in advance. 

Historic data shows that snowfall during moderate-to-strong El Niño events — like the one expected this winter — strays farther from the average, according to an analysis by Michelle L’Heureux, a meteorologist with the Climate Prediction Center. 

“Stronger El Niño events tend to land a larger punch on our atmosphere, thus increasing the chance of seeing expected El Niño impacts,” explained L’Heureux in his analysis posted last month.

For Nevada, moderate-to-strong El Niño events in the past have resulted in significantly more snow across large swaths of the state, especially throughout eastern and western Nevada, according to data analyzed by L’Heureux. His analysis also revealed that moderate-to-strong El Niño events brought significantly more snow to regions that provide Nevada water from snowmelt, including the Sierra Nevada mountain range and the western Rocky Mountains.