Precipitation and the lack thereof were the dominant players in the 2017 world of weather in Ravalli County.
Overall, the National Weather Service calls 2017 “a wild, crazy year” in the Northern Rockies, noting that average temperatures for December through February were the coldest readings since the winter of 1992/93, and the first three months were the second wettest on record, followed by the driest summer since 1929.
The year started off slowly, with early January headlines warning about the high-mountain snowpack lagging in the Bitterroots. By Jan. 5, the Bitterroot basin’s snowpack was 85 percent of normal for that time of year. Yet on the valley floor, below-normal temperatures kept the snow on the ground.
In the National Weather Service’s “Spotter” newsletter, the federal agency noted that a prolonged deep freeze that began in December didn’t end until February. Missoula received 64 inches of snow, while the average is about 38 inches.
The long-range forecast at that point called for average temperatures and a slight chance of above-normal precipitation. Yet in early February, the temperatures rose into the low 40s, and the snowmelt triggered winter flooding in low-lying areas in the Bitterroot.
The spring remained cool and wet in March and April, with the Spotter newsletter noting that “many days passed without the sun being seen, making for gloomy conditions for many residents in the Northern Rockies.” In fact, of the 61 days in March and April, only 11 days were dry.
By April, snowpack levels in the mountains surrounding the Bitterroot Valley were close to average for that time of year, but by May the snow melt was about two weeks ahead of schedule and most of the snowpack in the Sapphire Mountains was gone.
Slow-moving storms in early June helped crops and grasses grow, and a “significant rain event” caused historic flooding in the Sapphire Mountains down along Rock Creek. But by the end of the month, forecasters already noted record-high temperatures, record-low stream flows, and warned that a record-setting heat wave was on the way.
“All of a sudden, the faucet was turned off and the heater was cranked to full blast,” noted the National Weather Service. “July turned out to be the fourth warmest on record and the heat continued on into August.”
The summer of 2017 was the driest on record since 1929, and by mid-September, only one day since June 21 had measurable precipitation.
The hot, dry weather led to crews from the Bitterroot National Forest extinguishing 65 wildfires that summer, with more than 43,000 acres burned across the forest. That didn’t include the 54,000-acre Lolo Peak fire, which started on the Lolo National Forest and eventually burned into the Bitterroot.
The blessed fire-season ending event came in the form of snow in late September, and the snowfall got the big-game hunting season off to a good start in November, with anywhere from one to two feet of powder in the mountains.
The snowpack melted in the lower elevations, but enough was left up high for Lost Trail Powder Mountain to open for the ski season in mid-November — about two weeks early.