From The Valley Courier (Ruth Heide):
“Nothing new under the sun” was pretty much the message delivered by State Climatologist Nolan Doesken yesterday during a gathering of area water leaders. Although winters have tended to be warmer, dry years more plentiful and snowfall melting off sooner in recent years, the major factors that determine the Rio Grande Basin’s climate have not changed, Doesken explained.
Colorado is still the highest elevation state in the union; it still remains in a mid-latitude location between the pole and the equator; the state is still interior continental, not any closer to an ocean than it ever was; complex mountain topography remains; and solar energy is still constant, with hundreds of sunny days a year.
In a state that boasts 300 days or more of sunshine a year, the Rio Grande Basin, which encompasses the San Luis Valley, is the sunniest part of the state, Doesken reminded the audience of the Rio Grande Roundtable group on Tuesday.
“Most of the main drivers of our climate are not changing ,” Doesken said. “Our high elevation isn’t changing, our mid-latitude location isn’t changing “”
He added, “It does appear over time there’s been a bit of a warming trend in much of the state, but down here it’s mixed signals.” He said summer days in Alamosa have been distinctly on the hot side in recent years, and when Alamosa is 90 degrees, that generally means the entire state is pretty warm.
However, Doesken said the weather station in Del Norte has recorded a colder trend, which might be attributable to a change in the weather station’s location itself.
Of the weather data available for the Valley, “Most locations show a modest upward trend in temperature,” he said.
“Precipitation, on the other hand, is all over the place.”
He said there is no discernable upward trend in precipitation. This basin’s biggest climate indicators are found within the basin itself, Doesken explained.
“It’s a local effect.”
He said if the data from 1925 to the present were examined, for example, temperature changes might be as easy to determine here as answering the question, “When did it snow last?”
Regarding Valley temperatures , residents have learned to dress in layers, because the temperatures can vary so much, even in a single day, Doesken said.
“You are the champion of diurnal range fluctuations, day to night,” he said. The Valley can experience a 50-degree temperature swing from morning to night on a routine basis. It can be 20 degrees in the morning and 70 in the afternoon.
“That’s the climate in which you live,” Doesken said.
“In the Midwest, Mississippi Valley, going north means colder, south means warmer, but in the mountains it’s local topography that drives temperatures.”
The variability of the Valley’s weather is what remains constant, or as Doesken put it, “Variability will drive us crazy and keep us humble.”
Sometimes there will be an apparent cycle of weather, while at other times it will appear random. One constant is the spring wind that the Valley experiences from March through June.
“You are in your fourmonth wind season right now, like it or not,” he said.
Regarding precipitation, this basin is dry, like it or not. Doesken said because of the basin’s location, it generally receives less than 8 inches precipitation annually , which is the climate area residents know and love.
“You love it as long as the mountains around you are full of snow. They are not always.”
The bulk of the state’s legitimate surface water comes from those mountain snows, but that can vary as much as the temperatures. Because of the moisture that came into the state last fall the majority of it in one week Denver wound up experiencing its wettest year, Doesken said. Doesken reminded the group of the fact most were painfully aware, that the Rio Grande Basin has not enjoyed a big snowpack year for a while.
“Drought happens. It keeps happening,” Doesken said. He said there have been more years with less snowpack by April 1, “but there’s a lot of noise in there.”
He explained how important it is to keep data and said the manual snow course collection sites are extremely valuable. He has been a proponent of maintaining those sites in the state.
He has served in the Colorado Climate Center since 1977 and has been the state climatologist since 2006.
“We are climate accountants ,” he said. The center monitors all aspects of climate in the state from humidity and temperature to precipitation and evaporation . Doesken said the first government weather state in Colorado was located at Fort Massachusetts in the San Luis Valley in 1855, and by 1890 there was a statewide weather reporting network that included sites like Monte Vista and Platoro.
That type of information is still valuable, and Doesken encouraged local residents to become part of the Community Collaborative Rain, Hail & Snow (CoCoRaHS) network that depends on folks in places like Villa Grove to provide weather information to the state climate center. Those interested in becoming a part of CoCoRaHS are welcome to attend an open house from 2-7 p.m. on Friday, March 21, at the Colorado Potato Administrative Committee office , 1305 Park Ave., Monte Vista.
More IBCC — basin roundtables coverage here.