Cloud seeding will stop about a month early over the Sierra Madre Mountain Range in southern Wyoming because of the high snowpack this year.
The state of Wyoming sponsors cloud seeding programs in three mountain ranges in the state – the Wind Rivers, Medicine Bow and the Sierra Madres.
“The goal is to increase snowpack slowly and incrementally over long periods of time,” said Julie Gondzar, Wyoming Water Development Office project manager. “There's often a misconception that cloud seeding is this technology that creates clouds out of nothing and makes it snow out of nothing and turns blue skies into cloudy skies.”
Instead, Gondzar said the technology just helps clouds that already have high potential for snow produce more snow. They have been cloud seeding in the state since 2014 to try to help with declining water resources in the Colorado River Basin.
This year, the Sierra Madre’s have received high enough snowpack to stop cloud seeding operations early.
“The past several winters, we haven't had to suspend operations because our snowpack never reached that point where we say, ‘Okay, we need to stop seeding because the snow water equivalent is high enough,’” Gondzar said.
The Sierra Madre’s snow water equivalent (SWE) is 157 of average. Snow water equivalent is “the depth of water that would cover the ground if the snow cover was in liquid state.”
Operations will still continue in the Winds and Medicine Bow through mid-April. Even though the ranges have seen a lot of snow, the threshold to stop cloud seeding is pretty high.
“So the suspension threshold is a little bit less earlier in the season, and a little bit greater later in the season,” Gondzar said. “So it's not like a flat line, if you think about the suspension criteria as a line on a graph increases slowly throughout the season.”
By April 1, the SWE would have to be at about 140 percent of average. Both ranges are still below that criteria.
The last time cloud seeding operations were suspended was in the Wind River Range during the 2016/2017 winter because the snowpack was particularly high early in the season.
The typical cloud seeding season is from November to mid-April.