Breakdown: What a super El Niño means for Colorado, according to the Colorado Climate Center

“The brewing super El Niño may offer some hope, but a wide array of outcomes are possible this winter”

The Colorado Climate Center released a report on Sept. 3 describing what a super El Niño could mean for Colorado. The report has a cautiously optimistic feel about what Coloradans could expect from the weather phenomenon for fall, winter, and spring.

But also explains what is currently happening and why.

Assistant State Climatologist and report author Peter Goble details multiple elements explaining the weather phenomenon forecast and its global and Colorado impacts.

Here’s a breakdown from Goble:

The Core news:

• El Niño officially began in June, according to the National Weather Service, and continues to strengthen, according to the International Research Institute. The latest weekly Niño 3.4 index, centered on Aug. 12, reached +2.7 °C. 
• There’s a greater than 90% chance it becomes a full “super” El Niño (sea surface temperature anomaly of +2.0°C or higher).
• There’s a greater than 50% chance it becomes the strongest El Niño since modern record-keeping began in 1950.

What is El Niño actually and its effects:

• A climate pattern where trade winds weaken, letting unusually warm water spread across the eastern tropical Pacific instead of staying concentrated near Indonesia.
• Named by Peruvian fishermen (Spanish for “little boy,” referencing Christ) after noticing the warming tends to show up around Christmas.
• Its effects ripple globally: wetter conditions in the eastern Pacific, drier conditions in the Amazon, and altered mosquito-borne disease patterns in South America.

What El Niño typically means for Colorado:

• El Niño years tend to run wetter statewide, especially in fall and spring.
• The Front Range and eastern Plains see more large spring snowstorms and fewer dry, windy spring days during El Niño, however, though those days never fully disappear.
• The link to peak mountain snowpack is weak overall, but southern basins like the San Juan/Dolores/Animas/San Miguel and Rio Grande show a loose positive correlation with El Niño.

The big caveat; Stronger El Niño doesn’t guarantee a bigger payoff:

• There have only been three “super” El Niños in the modern record: 1982/83, 1997/98, and 2015/16.
• Only one of those (1982/83) actually delivered a huge snow year for Colorado, the other two produced roughly average conditions.
• Goble is upfront that three data points aren’t enough to draw firm conclusions, and there’s no known physical threshold where impacts suddenly scale with El Niño’s strength.

The climate-change wrinkle:

• Colorado’s climate has changed since 1982/83. The state is warming and western Colorado’s average precipitation appears to be trending down.
• Those historical correlations don’t account for this shifting baseline, so “El Niño = wet year” isn’t a safe assumption anymore.

• Even if the storms show up, more of that precipitation may fall as rain rather than snow, especially at lower elevations.
• Colorado is currently in severe drought, driven largely by last winter’s poor snowpack and record warmth, which is exactly why there’s a strong appetite for this El Niño to deliver.

Goble said he remains cautiously optimistic about how a super El Niño will play out for Colorado this fall and winter.

“The brewing super El Niño may offer some hope, but a wide array of outcomes are possible this winter,” Goble said. “It is a bit like playing a game of poker with a few extra aces and kings in the deck. The deck may be stacked in our favor, but we could still draw a crummy hand.”