Cold winds, heavy rain and snow dropped temperatures in and around Challis last week, bringing the weekly low to 34 degrees with 1.56 inches of precipitation.
“Over the last several years, we’ve noticed it’s not unusual to get snow in June,” John Keyes, a meteorologist with the National Weather Service in Pocatello, said. “It’s not unexpected anymore.”
Cold, dry air from the Northwest combined with heavy rainfall last week to cool the air temperature to the point rain became snow, he said.
“It will sometimes rain hard enough and long enough for the rain to cool the air to the point where it starts to freeze,” Keyes said.
The resulting cold weather left Challis and the valley where it lies in a cold monsoon. On June 16, the rain began at about 11 a.m. and didn’t stop till 4 p.m. the next day.
A few miles outside of Challis, on Garden Creek Road, driving conditions became difficult as the waterlogged road turned slippery. As the road led to slightly higher elevations at the Challis Motorway and in the forest, the ground became obscured in a patchy layer of snow.
Challis wasn’t the only town in Custer County struck by cold weather. Gary Gadwa, a Stanley resident who tracks weather for the National Oceanic and Atmospheric Administration, said “we had just a little bit of everything.”
Gadwa said he tracked about an 1.5 inches of rain and a couple inches of snow in Stanley last week. He said it rained June 15, 16, 17 and 18 consistently with snow falling each morning. Banner Summit, which is about 25 miles west of Stanley, received between 5 and 7 inches of snow. The coldest temperature he tracked happened Monday, June 15, when the thermometer fell to 24 degrees.
Keyes said most of Central Idaho was hit by the cold snap. In Lemhi County, he said the weather service tracked between 6 and 12 inches of snow in the higher elevations while rain fell in Salmon.