Colorado weather pattern pulls a switcheroo

Perhaps after the record runoff Northern Colorado enjoyed last year almost anything was going to be a disappointment, but February data indicated that snowpack across the state this year is way behind schedule.

“Nobody’s pushing the panic button quite yet,” said Reagan Waskom, director of the Colorado Water Institute. “But the jet stream is still tracking north of us and we need some of those March and April storms to hit.”

Statewide the snowpack was at just 76 percent of normal in mid-February, according to information from the Natural Resources Conservation Service. The Colorado River basin was at 72 percent of normal and the South Platte basin at 86 percent. Trans-mountain deliveries from the Colorado basin are on pace to deliver about half the water moved last year to the northeastern part of the state.

But that is not the entire story, said State Climatologist Nolan Doesken, even disregarding the fact that 30 percent to 40 percent of the snowpack will normally accumulate in March and April. Lower-level snowpack does not figure much into NRCS’s Snotel data, which tracks mostly high-elevation sites, and reservoir levels are high in Northern Colorado.

“It’s just the opposite of last year, where the northern mountains continued to get hammered but the eastern plains and southern mountains continually were missed — from 3 miles east of the Divide into the plains there was nothing,” Doesken said.

This year, the storm tracks that have favored the mountains of Arizona and New Mexico — good news for those parched states — have also hit the plains and eastern foothills pretty much up to, once again, within 3 miles of the Divide.

Quite a bit of that snow is not figuring into the NRCS data. Indeed, the reported lack of snow would be hard to believe in many parts of the eastern plains and foothills, especially in Boulder County where drifts piled in parking lots for much of February.

That early February storm and subsequent weather patterns did elevate snowpack data for the northern mountains, but the snowpack in the southern mountains fell from encouraging early winter numbers. Without a doubt, Doesken said, the early February storm did a great deal of good for the winter wheat farmers in the plains, many of whom are entirely dependent on soil moisture and spring rains.

“But the dryland farmers will still need those spring rains,” Waskom said. “And irrigators depend on the high-elevation snowpack to keep the streams running later in the summer.”

Another La Nina year
Many experts expected a return of the La Nina pattern that was exceptionally pronounced last year –- snow slamming the northern mountains and drought conditions continuing in many southwestern states. But it goes to show that eastern Pacific Ocean temperature oscillation that defines an El Nino or La Nina pattern –- warmer ocean temperatures for El Nino and colder for the sister pattern -– isn’t the end all for forecasting winter storm patterns.

“It certainly hasn’t been an El Nino pattern, and no two La Nina years are exactly the same -– especially back to back,” Doesken said. “But last year was really special. It was an extreme example of what you expect a La Nina year to be.”

For the Northern Colorado Water Conservancy District, reservoir levels are a saving grace, said spokeswoman Dana Strongin. On the eastern side of the Divide, Carter Lake was at 54 percent of total capacity while undergoing maintenance work and Horsetooth Reservoir was at 81 percent full, but filling those reservoirs is not expected to be a problem with the excess water on the Western Slope.

“We’re at 126 percent of average (for this time of year),” Strongin said. “Obviously, it hasn’t been a totally pretty picture, but because we have this water in storage from the last two water years, we don’t need to sweat about meeting demands this year.”

Overall, Northern Water is expecting its eastern runoff to be decent, while streams feeding Lake Granby on the Western Slope were only predicted to run at about 82 percent of normal, according to February forecasts.

“That February storm obviously gave us an uptick over what had fallen,” Strongin said.

And an uptick for the record books as well, said Doesken, noting that for many areas, it was the biggest February storm for quite some time.

“It just goes to show that if you wait 125 years, something different will happen,” he said.