A look at what to expect from the early Water Year 2018

Three month precipitation outlook through November 30, 2017 via the Climate Prediction Center.
Three month temperature outlook through November 30, 2017 via the Climate Prediction Center.

From The Aspen Times (Scott Condon):

The National Weather Service isn’t expecting the winter to be dominated by El Nino, when temperatures in the Southern Pacific Ocean are above normal, or La Nina, when temperatures are below normal. Instead, they expect El Nino Southern Oscillation Neutral conditions, known as ENSO Neutral.

“Basically what that means for us in western Colorado is a wildcard winter,” said Megan Stackhouse, a meteorologist with the weather service in Grand Junction. “There is no preferred track for storms. If we happen to be in the storm track, we can be wet and snowy. If we are more likely out of the storm track, we will be dry.”

Past winters with ENSO Neutral conditions brought a mixed bag to western Colorado. In 2012-13 and 2014-15 there was below normal precipitation across Colorado for the winter, she said. In 2013-14 there was above normal precipitation across the northern and eastern areas of the state.

“One thing that all three of those winters had in common was the presence of a persistent ridge of high pressure situated over the West Coast,” Stackhouse said. That tends to block low-pressure systems that drop in snowstorms from the northwest.

Aspen’s experiences during the three most recent ENSO Neutral winters were slightly different from the state as a whole. The Aspen Water Plant, which tracks weather data for the weather service, recorded 163 inches of snow in 2012-13 compared with an average of 155 inches going back to winter 1934-35. Snowfall at the water plant also was above average in 2013-14 with 200 inches.

Snowfall was below average in 2014-15 with just 149.5 inches at the water plant.

Winter outlooks are starting to dribble in from commercial forecasting firms and websites oriented toward skiers. AspenWeather.net, a micro-forecaster for the Roaring Fork Valley, will hold its annual winter outlook party Sept. 21 at the Limelight Hotel in Aspen.

Elsewhere, meteorologist Chris Tomer of OnTheSnow.com foresees the storm track cutting northwest to southeast through Colorado, producing “normal snowfall in the central and southwestern mountains and above-normal snowfall in the north.”

He fearlessly predicted 100 percent of normal snowfall at Aspen, Vail and Wolf Creek, while foreseeing 115 percent of normal snowfall at Steamboat and Loveland.

Tomer said the ENSO Neutral conditions in the Southern Pacific from September into early December were driving his forecast. However, he said he sees a shift toward a minor La Nina between mid-December and March.

Tomer also expects normal to slightly below-normal snowfall at California resorts after a monster season last year.

“Keep in mind this is an early-season, broad-brush forecast,” Tomer wrote. “It’s important to watch ocean temperatures in September and make adjustments.”

Joel Gratz, meteorologist at another online site for skiers, Open Snow, wrote this week that it is too early to make reliable predictions for the winter. Long-range forecasts are notoriously inaccurate, he said.

However, he was willing to share the latest of the long-range forecasts made by the U.S. National Oceanic and Atmospheric Administration’s Climate Prediction Center. Its outlook, released Aug. 17, indicated warmer than normal temperatures across much of the U.S. for December, January and February. Most of Colorado was forecast to be significantly warmer than average during those months.

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