The Colorado Climate Center, the National Integrated Drought Information System and other agencies hold regular conference calls to determine what the next regional drought map should look like. As you’d expect, the flood-drenched areas of the Front Range have been removed from any drought designation. Most of the Western Slope, though, remains in “moderate” drought, despite the fact that the Water Center at Colorado Mesa University reports most of the region received at least 150 percent of its usual rainfall between Aug. 18 and Sept. 16.
Long-Term Dryness Impacts
State climatologist Nolan Doesken said the western part of the state has had enough rain to relieve “vegetative water” issues — keeping everything green. Streamflow is another matter.
“We still have the impacts of long-term dryness,” Doesken said. That dryness means streamflows, which are still suffering a kind of hangover from 2012. Doesken said the snowfall we received in April and May helped bolster stream levels, but the ground on the mountainsides was so dry from the drought that much of the late-season snow soaked in before it could run off into streams.
While streamflows have stayed below normal this season, the massive rainfall on the northern Front Range has helped the Colorado River going into the fall, according to a report from Hannah Holm, coordinator of the Water Center at Colorado Mesa University. The Colorado is tapped for Front Range use, mostly from high-elevation reservoirs in Summit and Grand counties. Since there’s no real need for Western Slope water right now, reservoir levels and Colorado River streamflows will be healthier than usual this fall.
That will help the river going into the next “water year,” which starts Oct. 1. And, Doesken said, September rains have helped build ground moisture going into this next year.
And it’s the next water year — particularly the snowy part — that has local residents’ attention.
Neutral year A Mixed Bag
Long-range forecasting is still a tricky business, especially in fall and winter months. Instead of looking at storm patterns, weather watchers this time of year look to the Pacific Ocean off the western coast of Ecuador. That’s where water temperature in the ocean affects fall and winter storms moving into Colorado from the Pacific.
Warmer-than-normal water temperatures cause “El Nino” storms, while cooler-than-normal temperatures bring “La Nina” patterns. It was a La Nina that brought the epic winter of 2010-11, but a second straight year of that pattern brought the historic drought of 2012.
This year, water temperatures in that part of the Pacific are hovering around their historic averages. Those “neutral” years can be a mixed bag.
According to a recent long-range forecast from the National Weather Service office in Grand Junction, the 19 “neutral” years since 1950 have brought extreme drought, extreme snowfall or “average” water years. The report states, in essence, “This is what could happen — we don’t know.”
There’s a bit more confidence elsewhere.
Nearly-Average Fall Season
Doesken said that Klaus Wolter, a researcher at the Cooperative Institute for Research in Environmental Sciences at the University of Colorado at Boulder, has a more clear estimate for the fall. In the last drought report conference call Doesken said Wolter showed “distinct optimism” that the state could have a nearly-average fall season.
“Everyone (on the call) really breathed a sigh of relief when we heard that,” Doesken said. “It would really be nice to have a year that’s near average.”
Vail Daily Business Editor Scott Miller can be reached at 970-748-2939 or at firstname.lastname@example.org.