There is MODERATE Avalanche Danger in the west central Montana backcountry on terrain steeper than 35 degrees and above 6000 feet in elevation.
There is LOW Avalanche Danger on all other terrain in the advisory area.
Good Morning! This is Tim Laroche at the West Central Montana Avalanche Center with your backcountry avalanche advisory for Monday, March 19th, 2012.
Weather and Snowpack Analysis
Advisory area locations picked up 7-12 inches of snow since Friday, the southern Bitterroot Mountains receiving the higher amounts. The winds were moderate out of the south and west and mountain temperatures were in the low to mid thirties during the day. Currently, temperatures are in the mid twenties, winds are out of the north and west at 5-8 mph, and it’s snowing.
The new snow we have received is bonding well to the sun crustsA snow layer melted by radiation from the sun and subsequently refrozen. that developed early last week. It is settling quickly, but there are multiple weaknessesA snowpack layer with less strength than adjacent layers. Often the layer in the snowpack where an avalanche fractures. within the storm snow that are releasing easily on steep slopes with a human triggerA disturbance that initiates fracture within the weak layer causing an avalanche . In 90 percent of avalanche accidents , the victim or someone in the victims party triggers the avalanche .A disturbance that initiates fracture within the weak layer causing an avalanche . In 90 percent of avalanche accidents , the victim or someone in the victims party triggers the avalanche .. Watch for recently formed soft slabsA relatively cohesive snowpack layer. A layer of snow stronger than underlying layers. and loose snow sluffs to fail easily on steep terrain. Standard sluffA Loose Snow AvalancheA Loose Snow Avalanche or Sluff. or Sluff. management techniques will work well to keep you from getting caught by the loose debris.
Look for fresh wind drifts 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. sides of upper elevation ridges, as well as cross-loaded terrain features like gullies and sub ridges. These drifts are about a foot deep and should be mostly manageable if you are not caught by surprise.
The 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. layer, down 2-3 feet, that has been the cause of recent human triggered slides has continued to gain strength. This weak layerA snowpack layer with less strength than adjacent layers. Often the layer in the snowpack where an avalanche fractures. takes a lot of force to fail, but should still not be trusted. A slideA mass of snow sliding, tumbling, or flowing down an inclined surface. Same as avalanche. initiated in the upper snow pack could step down to this layer. So, dig down and look for this weakness before you commit to a steep slope.
When the sun comes out this week, pay attention to how the snow is changing. It will warm the surface snow quickly and produce wet surface snow slides on the buried sun crustA crust is a hard layer of snow where liquid water has refrozen into grain fabric. Crusts usually result from sun, rain or wind.. When the snow starts getting damp, move off the slope in search of colder snow.
Weather Forecast and Avalanche Outlook
There is a Winter Weather Advisory posted for our advisory area until noon today. Forecasts are calling for an additional 3-8 inches of snow in the higher terrain of west central Montana. Temperatures will stay cool until Tuesday when the next storm system arrives. The wet storm pattern will stay with us delivering moderate amounts of snow until Thursday, when we should see a brief break in the active pattern.
I expect the avalanche danger to remain the same with small doses of new snow accumulations throughout the week.
Dudley will issue the next advisory on Friday, March 23rd.
If you get out and have the time to send us some information about what you are seeing, please use our “submit observation” link on our website or send us a quick note at email@example.com. This information is invaluable to us and in turn comes back to you in the form of a better forecast.