A “flash drought” that hit Wyoming in summer and fall 2020 left more than 95% of the state abnormally dry or affected by drought, a big change from a year ago when only about a quarter of the state was affected by a lack of moisture.
The U.S drought monitor for Wyoming at the end of January also classified 26% of the state in “extreme drought,” one step below the most severe “exceptional drought” category. Experts say only 4% of the state — most of Teton County — had no dry or drought conditions on Jan. 26.
“We’re coming off a really bad season last year,” said Tony Bergantino, acting director of the Water Resources Data System in the Wyoming State Climate Office. “Soil moisture is abysmally low.”
While the balance of winter holds hope for additional precipitation, some people already are bracing for impacts should the dry trend continue. At the Worland Field office for the U.S. Bureau of Land Management, for example, range managers have notified those with grazing leases of potential impacts.
“If drought conditions do not improve, it is possible that there may not be enough forage to fulfill the total authorized [animal-unit-months] on your permit or lease for the upcoming season,” Worland BLM Field Manager Michael Phillips wrote permittees in a January letter. The U.S. Department of Agriculture in January designated Sublette, Lincoln and Crook counties disaster areas because of drought.
Wyoming’s snowpack averaged 75% of normal water content Monday, the National Resource Conservation Service reported. Last year at this time the median average was 140% and the year before it measured 137%.
Maps show the Madison and Tongue river basins had snowpacks with the highest water content in the state this week, measuring 96% and 90% of average respectively.
Spring precipitation may not make up for existing deficits, Bergantino said. “The snows we’re getting right now, it’s hard to tell what beneficial water is in those.”
Two issues affect today’s snowpack. For one, some of the snow will have no effect on soil moisture at all.
“Most of it is sublimating — going directly from snow into water vapor,” Bergantino said. “We’re losing a lot of that before it gets into the ground.”
Another issue is the dryness of the soil today. It will require some moisture just to get back to normal.
“Once that snowpack starts melting, a lot more is going to go to replenish that soil moisture before it can get to running off,” Bergantino said.
He described the state’s “flash drought.”
“We had some dry months followed by some warmer weather,” he said. “It was kind of a perfect storm getting this set up.”
2020 was the fifth-driest year since 1895, Bergantino said. August was the third-driest August, he said.
Specialists first applied the “extreme drought” classification — one level below the most severe “exceptional drought” category — to parts of the state on July 21, 2020, he said. The U.S. Drought Monitor assigned an “exceptional drought” label to parts of the state in November.
Although precipitation has ameliorated that slightly, the designation was remarkable, Bergantino said.
“The last time we had seen anything like that was [in the] 2012-’13 period,” he said, Wyoming’s driest ever. Without some relief in the snowpack, “I see things continuing … at this level or worse.”
Phillips’ letter to stockgrowers asks for planning.
“Residual forage that supported much of the livestock grazing in the 2020 grazing season is now limited or gone,” he wrote. “We are aware that changes to your livestock operation may cause uncertainty and economic hardship. Therefore, we would like to work with you now to plan for the upcoming season in order to maximize collaboration.”
Holders of grazing leases and permits should be ready to discuss changes to when stock is turned out on public lands, which pastures are used and how long animals may be allowed to graze, the letter said.