An avalanche warning is in effect for the mountains of west central Montana.
Good morning, this is Steve Karkanen at the West Central Montana Avalanche Center with an avalanche warning for mountainous locations above 5000 feet in western Montana.
SNOTEL sites this morning report over an inch of SWE and several inches of new heavy snow at locations above the snow line. Mountain temperatures are in the 30′s and are expected to drop through the day today. Winds are WSW at 40mph at 8000 feet and expected to increase this afternoon.
The Missoula Office of the National Weather Service is forecasting a strong upper level jet and a surface cold front to drop into the Northern Rockies today with high winds and heavy snowfall. Snow levels are expected to drop to valley floors this afternoon.
Weather and Snowpack Analysis
We’ve extended the avalanche warning for the northern mountains in the Rattlesnake, southern Swans and southern Missions near Seeley Lake. The Bitterroot range received additional snowfall overnight which has stressed the snowpack to the breaking point. Several small mostly loose snow avalanches or sloughs were reported to us the past few days which were not a cause for alarm as these were small and manageable.
The new snow, warmer temperatures and wind has formed a dangerous slabA relatively cohesive snowpack layer. A layer of snow stronger than underlying layers.A relatively cohesive snowpack layer. A layer of snow stronger than underlying layers. in most locations especially on leewardWind erodes snow from the windward (upwind) side of an obstacle and deposits snow on the leeward (downwind) side. Deposited snow looks smooth and rounded. You should always beware of recent deposits of wind drifted snow on steep slopes. terrain.
There are two factors to be concerned with. The past 24 hours have been relatively warm so the snow has been heavy and wet on top of much colder lighter snow we’ve been enjoying the past few days. The immediate impact of this is a poor bond between the new and older snow. The bigger problem is a layer of buried surface hoarFeathery crystals that form on the snow surface during clear and calm conditions - essentially frozen dewFeathery crystals that form on the snow surface during clear and calm conditions - essentially frozen dew. Forms a persistent weak layer once buried.. Forms a persistent weak layer once buried. crystals that have been found in nearly all locations that we’ve been monitoring. This layer has been the culprit in the close calls and sluffA Loose Snow AvalancheA Loose Snow Avalanche or Sluff. or Sluff. fest last weekend.
Weather Forecast and Avalanche Outlook
With the initial warm temperatures and heavy snowfall the snowpack will quickly settle and begin it’s adjustment to the change taking place today. As temperatures cool down the upper snowpack will begin bonding to the older layers and slowly get stronger. Expect dangerous avalanche conditions to remain at least through the period of high winds. Knowing that we have a layer of buried surface hoarFeathery crystals that form on the snow surface during clear and calm conditions - essentially frozen dewFeathery crystals that form on the snow surface during clear and calm conditions - essentially frozen dew. Forms a persistent weak layer once buried.. Forms a persistent weak layer once buried. with a stronger slabA relatively cohesive snowpack layer. A layer of snow stronger than underlying layers.A relatively cohesive snowpack layer. A layer of snow stronger than underlying layers. above it will require careful terrain management and a high level of situational awareness. The danger is obvious right now. It will get tricky once the weather settles down.
There was an avalanche fatality Monday in the Lost Johnny drainage of the South Fork of the Flathead river. Avalanche specialists from Glacier Country Avalanche Center are investigating the avalanche and will post details once they complete their work.
Dudley posted this observation Monday and I think it is worth leaving up for this period of high avalanche danger. I also watched a lot of risky behavior in the Snowbowl sidecountry the past few days. Conditions are a lot different now. The same behavior in these conditions isn’t just risky, it’s dangerous and irresponsible.
It’s time for my mid-winter rant about backcountry (I should say sidecountry) behavior. I was inspired Saturday when I watch three people ski an avalanche chute just outside the Snowbowl boundary together……at the same time. This particular slope had a large skier-triggered avalanche on it this year. I doubt these three riders read the avalanche advisory, so I’m aiming my comments at Snow Bowl parents who may have kids, teenagers or older, ducking the ropes or skiing out-of-bounds. Once you leave the ski area; you’re on your own. The areas just outside the ropes are backcountry. There is no slope management or patrol. You should be prepared to deal with a burial or trauma. It would be a major operation to extract someone from the Rankin Lake basin just outside Snowbowl. Folks are treating this terrain as part of the ski area. It’s not. Do you think people who would ski three at a time down an avalanche chute know when the snow is stable and when it isn’t?
We just had a terrible incident in the sidecountry near Stevens Pass, Washington. Bozeman experienced a major avalanche on Saddle Peak (where everyone hikes) just outside Bridger’s boundary a couple of seasons ago (fortunately no one was hurt). Everyone wants to ski the gnarly terrain; the sidecountry is popular. Have you talked to your kids about drugs, avalanches and skiing out-of-bounds?
Check out this video from the Gallatin Avalanche Center. http://www.mtavalanche.com/sidecountry