Montana is bracing for a potentially historic September storm over the weekend with the possibility of more than 30 inches of snow on Marias Pass along the Continental Divide and winds gusting up to 50 miles per hour out of the northeast.
As the storm rolls in from Canada on Friday into Saturday, high elevations can expect heavy, wet snow and blizzard conditions while the valley will see rain accompanied with high winds possibly causing boat and dock damage on Flathead Lake, according to National Weather Service officials.
On Sunday, the Flathead Valley will shift from rain to snow and gusts will taper off to around 20 mph. Heavy, wet snow could bring down tree branches and cause power line damage.
During the storm’s final phase on Monday and Tuesday, temperatures will drop into the teens on Marias Pass, while Kalispell will see lows in the 20s. Cold temperatures could damage irrigation lines and create difficult conditions for livestock, according to NOAA officials.
“This is something that’s definitely very abnormal for this time of year,” Jennifer Kitsmiller with the National Weather Service said on Sept. 26.
While fall storms are rare on this scale, Kalispell saw a low of 16 degrees in September 1970 and winds caused multiple damaged boats and docks on Flathead Lake. Similarly, in September 2000, wind gusts of 60 mph caused 10-foot high waves on Flathead Lake.
The historic blizzard will also create dangerous backcountry conditions, which prompted the Flathead Avalanche Center to issue a fall travel advisory.
Even with a low snowpack, Flathead Avalanche Center Director Zach Guy reminds recreationists that avalanches are still possible and should carry appropriate avalanche rescue gear.
Skiers, hunters and hikers should be especially wary in high elevations and steep slopes with a smooth base, which Guy says could be the right ingredients for an avalanche.
“In early season the thing to consider is if you get caught in an avalanche, it’s gonna drag you through rough terrain that’s otherwise covered by snow,” Guy said. “It can drag you down rocks and stumps.”
Travellers should also be aware of gullies and wind-loaded slopes, which are the first terrain features to accumulate snow and develop a snowpack. If snow is anchored by logs or trees, Guy says those areas shouldn’t be an issue.
Although fall avalanches are uncommon, Guy says they do happen. In October 2017, a skier was killed in an avalanche in the Madison Range south of Big Sky. Two skiers were caught in the slide with one partially buried while the other skier was fully buried three feet deep.
Montana Fish, Wildlife and Parks Region 1 also reminded hunters and outdoor recreationists on its Facebook page to be careful over the weekend, noting that “hazardous travel” is expected.
While the Flathead Avalanche Center isn’t currently operating, Guy says it will post updates as needed on its website and social media throughout the fall if conditions change. Daily updates are estimated to begin in late November or early December.
For more information, visit weather.gov/mso and flatheadavalanche.org.
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