Yes, Southwest Colorado’s snowpack was listed at 3,328% above historic averages Wednesday. But no, that doesn’t tell the whole story about the remaining snow high in the San Juan Mountains.
“It is very eye-catching,” Brian Domonkos, a snow survey supervisor for the Natural Resources Conservation Service, said of the number. “But unfortunately, it’s not the easiest way to relay (how much snowpack is left in the San Juan Mountains).”
Nearly every day, the NRCS updates the amount of snowpack in eight river basins throughout Colorado. In Southwest Colorado, which accounts for the Animas, Dolores, San Juan and San Miguel basins, about 19 sites ranging in elevation from 9,000 to 11,600 feet track snowfall throughout the year.
The maps, Domonkos said, are more useful in the middle of winter, when there’s a strong base of snow to compare with previous years. Later in the season, however, the numbers jump around and are not as effective in communicating the actual amount of snowpack in the high country.
As of Wednesday, there was about 5.2 inches of snow-water equivalent across the Southwest Colorado basins. The percentage of normal is so high because the median for June 19, based on 30 years of record-keeping, is 0.2 inches of snow-water equivalent.
“By June 19, the snow is usually all melted out, at least from where we measure,” said Peter Goble, a climatologist with the Colorado Climate Center. “That’s why those numbers are so jarring.”
This past winter brought a robust snowpack to the San Juan Mountains, Goble said, one of the best in the last 40 years. Then, a colder-than-normal May (the coldest since 1995) set the conditions for snowpack to linger in the high country.
“That’s why, when you compare this year to the average, the numbers tend to jump off the charts,” he said.
But this year, snow remains in the high country that has yet to come down: As of Wednesday, about 18% of this winter’s total peak snowpack had yet to melt – meaning the region has likely already hit peak river flows and the amount of runoff is steadily on the decline.
“It’s worth mentioning our (weather) sites sit at set elevations, but there is snow still above those elevations,” Domonkos said. “But even still, the elevations above our monitors are not the significant driver for runoff.”
Snow tracking sites, too, vary throughout the basin. On Wolf Creek Pass, at an elevation of 11,000 feet, there’s nearly 20 inches of snow-water equivalent. But at Molas Lake, at an elevation of 10,500 feet, there’s no reported snow-water equivalent left.
Despite all the variations, most of Colorado’s reservoirs are expected to refill after one of the worst drought years in recorded history in 2017-18.
Lemon and Vallecito reservoirs, for instance, are about 90% full. Both reservoirs, east of Durango, were at near record lows this fall and winter.
“It looks like many reservoirs in the state will fill,” Goble said. “Even some of the ones that were critically low over the winter following the drought in 2018.”
And, it appears winter hasn’t totally released its grip on Southwest Colorado: The National Weather Service is calling for a slight chance of snow in the high country Saturday night.