Storm 'plasters' county, but 70s to return before longSep 15, 2017 By Katie Roenigk, Staff Writer
National Weather Service meteorologist Dave Lipson said he knew the wildfire that started Wednesday afternoon above Fort Washakie didn't have long to burn.
"We saw that fire from here," he said Friday at his office west of Riverton. "We knew it didn't have much of a life - maybe 48 hours."
It only takes one-tenth of an inch of rain to quench a fire, he said, and on Thursday and Friday the St. Lawrence Basin area, where this week's wildfire was located saw 1-2 inches of precipitation.
"At or pretty near the fire are some of the wettest areas of this storm system," Lipson said. "A pretty good thunderstorm dumped quite a bit of rain in that area yesterday - if it wasn't right on the fire, it was pretty near it."
Other parts of Fremont County got doused too, he continued, with 1.7 inches recorded in Dubois, 1.67 inches in Crowheart and .4 inch in Riverton.
Between 7:30 a.m. and 11 a.m. the rain gauge near Lipsons' house between Riverton and Kinnear collected .94 inch, and he said residents just south of Kinnear "got nailed" with precipitation.
"Everybody's getting a wetting rain pretty much," he said. "(It) has plastered most of the state."
At Fremont County's higher elevations - 8,500-9,500 feet and above - the precipitation is falling in the form of snow, Lipson said, with 1-3 inches on the ground Friday morning forecast to grow to 12-14 inches by the end of the weather event mid-day Saturday.
"You could have maybe 9 inches up around Blue Ridge - the highest point in the Loop Road," he said. "And a good swath of the Absarokas will see over a foot above 9,500 feet."
As with the type of precipitation, temperatures also will differ based on elevation. In Riverton, Lipson said it was 42 degrees mid-morning Friday, but at Boysen Peak - 7,300 feet above sea level in the Owl Creek Mountains - it was 32 degrees.
"That freezing level - the snow level - will descend through the rest of day, tonight, and tomorrow morning," Lipson said.
Once Saturday is well under way, he continued, the precipitation will dissipate, and temperatures will rise, possibly reaching 70 degrees by Sunday to melting much of the snow that is forecast to fall.
"Some should stick around to be the very base of this winter's snowpack, but ... even up in the mountains a lot of that snow should melt," Lipson said.
High temperatures Monday will be in the 50s at 7,500 feet, he forecast, and at the 10,000-foot level they should reach the upper 30s "at the coldest."
"Even that is enough to melt snow," Lipson said. "A lot of it won't last."
Current temperatures are below normal for the Wind River Basin, Lipson said, but this week's weather event is "not unprecedented."
"It's early kind of ... but it happens," Lipson said, adding, "I think we're later in the season than people realize because we've been kind of spoiled by the summer weather."
The system is a combination of elements that came together from the southwest, west and northwest, he explained, though the moisture is all coming from the Pacific Ocean.
"The Pacific moisture is getting sucked in, and it's being drawn inland and around the base of the main trough axis, which is still over the Great Basin and streaming up from the southwest," he described.
The element from the northwest involves an "upper-level weather disturbance," Lipson continued.
"That's what's supplying the cold air," he said. "So we have surface dynamics the cold front is producing, helped with two different surface wind trajectories ... plus all these other complicated upper level weather dynamics going on.
"All of those dynamics and moisture is spelling out snow - or at least a lot of widespread precipitation, with rain in most areas and snow in the mountains."
The weather should put an end not only to Fremont County wildfires, but to the blazes that have been burning continuously in areas northwest of Wyoming, particularly in Montana. Lipson said this system marks the slow-down, if not end, of the fire season.
"We won't be seeing smoke from ours or their fires," he said. "So if it clears up Saturday afternoon, we'll see crystal clear, blue skies between the patches of clouds - which will add to the ambience of the crisp fall air."