El Nino's return could spell dry, warm winter for Western Montana

Above normal temperatures and below average precipitation is projected for Western Montana this winter as a strengthening El Nino climate pattern takes hold for the first time in four years.

The National Oceanic and Atmospheric Administration issued its winter forecast Oct. 19 for the northern tier of the U.S., calling for a strong El Nino influence.

Northwest Montana will feel the brunt of the impacts, according to Bob Nester, a senior forecaster with the National Weather Service in Missoula.

Northwest Montana snowpack during a strong El Nino historically ranges from 75-90% of average. Kalispell averages about 76% of normal snowfall, while West Glacier averages about 81% of normal.

“That’s mainly due to not has many strong westerly [jet streams] bringing a lot of Pacific moisture to the region,” Nester said, adding that the jet stream typically stays to the south during El Nino.

Much of Northwest Montana is already experiencing severe to extreme drought conditions.

Meanwhile, average temperatures in Northwest Montana during an El Nino winter are typically 2 to 4 degrees above normal.

“We just don’t get that many arctic air masses with this type of pattern,” Nester said.

Conditions will be ripe for fog and inversions in valley locations, with more frequent high pressure ridges, Nester said.

February is most likely to exhibit the strongest El Nino characteristics, based on historical data.

“February seems to be the month where there is the greatest correlation to above normal temperatures, and the precent of normal snowfall is much lower,” he said.

Still, he cautions that not all El Nino winters are the same. There are some outliers, such as the winter of 1994-95 and 2015-16, where Western Montana precipitation finished the season above average.

“It doesn’t mean we’re not going to have snow,” Nester said. “We’re still going to have those snow events and colder events, but not quite as frequent.”

While Montana is poised to miss out on a big winter, forecasters say El Nino brings wetter-than-average conditions for northern Alaska, parts of California, south-central Rockies, the southern Plains, Gulf Coast, Southeast and lower mid-Atlantic.