CHEYENNE — During a monthly weather briefing last week, Cheyenne National Weather Service Meteorologist Jared Allen talked about the “welcome moisture” last weekend’s record-breaking snowstorm had on Wyoming’s drought.
“We had quite a weekend,” Allen said. “A significant winter snow event, with Wyoming on the cold side of the storm getting wet, heavy snow.”
This impact of this moisture, he said, helped push fire season back a couple of weeks across the region – it normally starts at the beginning of March, then kicks into high gear between mid-June and mid-September – the first time in Allen’s recollection that fire season has been pushed back, instead of ahead.
Allen was also concerned about what happens when as much as 52.5 inches of snowfall – the official tally at Windy Peak, north and west of Cheyenne – begins to melt. This could create ice jams on the region’s rivers, causing flooding.
Those two indicators alone are quite different from the outlook just a month and a half ago.
Last summer and fall, what meteorologists deem a “flash drought” hit Wyoming.
It left some 95 percent of the state “abnormally dry” – quite a change from 2019, a wet year across Wyoming and the region.
As a result, at the end of January, the U.S drought monitor for Wyoming classified 26 percent of the state in “extreme drought,” one step above the “exceptional” drought classification, the most severe drought measure. Only 4 percent of the state had no dry or drought conditions by the end of January. Soil moisture was “abysmally low,” with 2020 being the fifth-driest year since 1895, Tony Bergantino, acting director of the Water Resources Data System in the Wyoming State Climate Office, told WyoFile.com.
The last time Wyoming saw such a drought was in 2012-13, when drought maps had the southern two-thirds of the state in exceptional drought.
“Snowmageddon” brought about 2 inches of precipitation to the region. As a result, there was a drastic change in snow/water equivalent amounts across the state, Allen said.
“The water budget looks healthy and normal now,” he said.
Snow/water equivalents are how hydrologists and water managers measure the amount of life-giving liquid water in snowpack when it melts.
Statewide, prior to the storm, this number stood at about 75 percent of normal.
As a result of the storm, that number is now 100 percent or plus in many areas, Allen said. Where the storm hit hardest, between Arlington and Gillette, the numbers range from 115 percent to 118 percent.
Brad Pugh of the National Drought Mitigation Center in Lincoln, Nebraska, noted that the storm “eliminated precipitation deficits” and resulted in “precipitation surpluses” for the past 90 days for much of the Central Plains. As a result, a broad one-category improvement was made for drought areas that received an inch or more of precipitation.
Cheyenne, meanwhile, remains at 76-percent of normal – although Allen pointed out that most of Laramie County’s winter and early spring moisture comes between March and mid-April.
“Unfortunately, while this was a shot in the arm and brought the playing field up a bit, it didn’t end the drought – far from it, especially in some places,” Bergantino said.