Tropical moisture fueled storm

Camille Erickson, Casper Star-Tribune via Wyoming News Exchange
Posted 3/16/21

What caused this weekend’s massive storm?

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Tropical moisture fueled storm


CASPER — Wyoming was pummeled with one of the biggest snowstorms in the state’s history this weekend. The storm dropped more than two feet of snow in many parts of the state, leading to power outages, stalled travel and shuttered schools. 

What caused this weekend’s massive storm? 

Local meteorologists said a low pressure system brought a significant amount of tropical moisture up into the high plains. That high level of moisture, pulled in from the southwest, meant the snow had a lot of water content. 

High wind gusts mixed with heavy moisture led to sustained blizzard conditions, especially in southeast Wyoming.

Those conditions then stalled over Wyoming and Colorado for multiple days, according to the National Weather Service in Cheyenne.

“This storm was pretty impactful,” said Ayesha Wilkinson, a meteorologist at the National Weather Service in Cheyenne. “It really was a lot of moisture, because we’re not used to getting so much moisture in the high plains.”

Meteorologists had initially forecast between 26 and 30 inches of snowfall in southeastern Wyoming. Although snowfall totals can vary within a mile, weather forecasters said snow around Cheyenne piled up to around 21 to 36 inches. 

“I think we pretty much nailed it,” Wilkinson said of her team’s predictions.

The National Weather Service in Cheyenne and Riverton were still finalizing total snowfall data as of Monday morning. 

But weather service staff received reports of 28 to 30 inches of snowfall around Wheatland, near Interstate 25. 

The National Weather Service in Riverton reported 26.3 inches of snow at the Casper-Natrona County International Airport, as of Monday morning. Three miles east of Casper, the weather service center received reports of 26.5 inches of snow. About 22 inches of snow fell in Reno Hills, up in the Casper Mountain area.

Wet snow is compact and difficult to shovel. Experts caution residents to take frequent breaks and drink water when shoveling to avoid injury. 

Cumulatively over two days, the water content from the snow came to 2.1 inches. 

“It was very, very moist snow,” said Riverton meteorologist Micha Holme. 

The exceptional volume of wet snowfall will be somewhat helpful for the dry region, currently experiencing a severe drought. 

Weather conditions for the remainder of the week will likely be much milder than what the state witnessed over the weekend, according to the weather service. There could be some light snowfall on Monday and Wednesday around Cheyenne. But dry and warm conditions could arrive as soon as Thursday, with temperatures in the upper 40s. “Nothing like we saw the last few days,” Wilkinson said of this week’s forecast. 

In recent years, climate scientists have started to identify potential links between the increase in record-breaking extreme precipitation events and global warming.