Extreme El Niño adds moisture to Southwest storms, scientists say

A peak in Pacific heating is still ahead

Flash floods on Sunday prompted evacuations across northern New Mexico and central Arizona, while a Colorado ski town braced for its main river to rise to catastrophic levels. Scientists say an extreme El Niño is making heavy rains more likely and intense across the Southern U.S. by warming Pacific Ocean waters, adding moisture to the air and shifting winds toward the Southwest. They said the climate pattern is not the sole cause of the severe storms.

Another wet storm last week subjected southwestern states to days of flooding. Over 20 trillion gallons of water have fallen on the Four Corners states and Nevada in the past two weeks, according to calculations by former National Oceanic and Atmospheric Administration chief scientist Ryan Maue.

El Niño is a natural warming cycle that can occur irregularly every couple of years, but scientists described this iteration as particularly extreme. “We’ve had super El Niños in the past, but this is a super duper El Niño,” said meteorologist Jeff Masters of Yale Climate Connections.

The current event is adding more moisture to the air and shifting atmospheric winds toward the Southwest, creating more favorable conditions for storms, scientists said. “The likelihood of big precipitation in the Southwest interior does go up this time of year, but we’re seeing it to a degree we actually haven’t seen before,” said climate scientist Daniel Swain with the University of California Agriculture and Natural Resources.

The world’s oceans have already warmed over time because of human-caused climate change, and El Niño heats them even more. “The fact that the ocean temperatures are already warmer than they were, say, 100 years ago, makes these El Niño situations even more intense,” said meteorologist Randy Cerveny with Arizona State University.

The effects are not confined to the United States. El Niño is changing weather patterns around the world, with Peru and Ecuador seeing record-breaking flooding, Swain said.

The El Niño event is expected to peak in December, and experts expect its effects to continue for months afterward. “We’re not at the peak of the heating in the Pacific Ocean. So yes, we will see more of these particular events,” Cerveny said.

Experts recommended that people watch the forecast, plan ahead and heed evacuation warnings from local authorities.