After a sparse winter in the West, many are looking to headlines declaring a strong El Niño with anticipation — and hoping it’ll mean more snowfall.
“People want to know if it's going to bounce back and be a more normal snowy winter,” said Alan Smith, a meteorologist for the company OpenSnow, which is known for providing winter forecasts around ski areas.
On an optimistic note, Smith thinks it will, indeed, be a more normal winter for much of the West, at least compared with last year, “which was just completely abnormal in terms of warmth and lack of snow.”
But, he cautions, this doesn’t mean an amazing winter everywhere.
In an El Niño year, warmer Pacific Ocean temperatures shift the jet stream south and stretch it further east. Mapped onto the Mountain West, this often looks like a “tale of two halves,” said Scott Handel, the lead meteorologist at NOAA’s climate prediction center.
“Where the southern portion of the Intermountain Mountain West, say Arizona, New Mexico, and into parts of Colorado, Utah, generally are favoring above-normal precipitation — especially as we get into mid-winter and later — and the Northern Rockies are generally favoring below-normal precipitation,” he said.
The middle — the Great Basin, northern Utah and north-central Colorado — can be more of a toss-up.
But this El Niño is expected to be atypical, with forecasters pointing to a more than 90% chance of a very strong event in the fall and winter. There’s even a 69% chance that this El Niño will be the strongest since record-keeping began in 1950, Handel said.
“It's exceedingly rare to have this degree of confidence in this strong of an event the summer before an incoming El Niño winter,” he said.
Stronger El Niños tend to correlate with stronger impacts.
“In general, you tended to get greater snowfall than usual in the Southern Rockies, less snowfall than usual in the Northern Rockies, with the Central Rockies being kind of the battleground between the two,” he said.
In those years, the dividing line between the Mountain West’s haves and have-nots can also push further north, benefiting the states in the middle. But it’s not a slam dunk, Handel said.
That’s because the relationship between the strength of the El Niño and the climate impacts is not linear, said Joel Lisonbee, a drought information coordinator with the National Integrated Drought Information System, based at the University of Colorado Boulder.
“The likelihood of those really extreme events is higher with a really strong El Niño, but every El Niño plays out a little different. So, we kind of have to wait and see,” he said.
One big wild card is temperature. How warm it gets in the mountains could determine whether precipitation falls as rain or snow.
No matter how it turns out, Lisonbee emphasized that it’s not likely this winter will make up for the long-term drought in the West.
“It would have to be an exceptionally wet winter to make any noticeable difference in 20 years of drought in the West,” he said.
This story was produced by the Mountain West News Bureau, a collaboration between Boise State Public Radio, Wyoming Public Media, Nevada Public Radio, KUNR in Nevada, KUNC in Northern Colorado, KANW in New Mexico, Colorado Public Radio and KJZZ in Arizona as well as NPR, with support from affiliate newsrooms across the region. Funding for the Mountain West News Bureau is provided in part by the Corporation for Public Broadcasting and Eric and Wendy Schmidt.
