While much of Montana sits at or near normal for precipitation and snowpack, officials are keeping a close eye on a dry swath of the northwestern part of the state.
The Governor’s Drought and Water Supply Advisory Committee met this week in Helena following a winter marked by early warmth and then brutal cold and snow. The committee includes members of multiple state and federal agencies that track weather, streamflow, runoff and flood damages.
Early winter brought unseasonably warm temperatures for much of January. That changed dramatically in February with a record-setting cold front that plunged temperatures far below zero and dumped snow across valley floors. But in early March, the precipitation dried up.
“This is the challenge we have, we’re looking at February precipitation well above normal, some of these areas are in the 300 percent,” said Troy Bladford, GIS analysis and water information system manager for the Montana State Library. “When we get to March it was very dry. We didn’t notice that because the snow was still there, it was just really cold.”
Despite the seeming back-and-forth of winter temperatures and precipitation, much of the state for mid-April sits near average for both. Exceptions to the statewide trend are Lincoln County in northwest Montana and the southern end of Bighorn County, which officials have identified as below normal for moisture but not quite at drought stage.
“The Northwest is our main area of dryness concerns … the rest of the state is looking really good,” Baldford said.
Megan Syner, meteorologist with the National Weather Service in Great Falls, noted that long-term temperature and precipitation averages were largely driven by extremes.
“When I say normal, that doesn’t mean we haven’t had extremes,” she said. “Overall because of these extremes for the year, we’re about normal.”
Meteorologists are closely watching trends going into May and June – the two wettest months of the year.
Interestingly, Syner noted that winter storm patterns along the Rocky Mountain Front caused more snow to fall on the plains east of the Front than fell in the mountains. That was largely due to storms coming from the north and northwest that entered through the northcentral part of the state.
While northwest Montana is the primary concern, northeast Montana saw much of its snow go downstream as runoff while the ground was frozen. That did not allow water to soak into soil.
When it comes to flooding, ice-jam related flooding has passed but flooding from mountain snowpack remains to be seen.
“We’re not seeing a lot of strong flooding signatures on main stem rivers, that doesn’t mean we’re out of the woods yet,” Syner said.
Officials do not see immediate flooding concerns in the near future.
“The best case scenario is what we’ve been seeing so far this year,” she said, with gradual warming and temperatures staying below 80 degrees.
Snowpack has likely peaked in the state for the year, said Lucas Zukiewicz, water supply specialist with the Natural Resources Conservation Service. In terms of mountain snowpack, the biggest area of concern is the Kootenai River. In part, the drying comes from tributaries in Canada, which saw a far-below-normal snow year, he said.
“We’re very unlikely to reach normal river flows in the Kootenai River Basin this summer,” he said.
The Tongue River is also forecasting for below normal, he added.