Avalanche Advisory January 31, 2014
On slopes above 6000 feet that are steeper than 35 degrees the avalanche danger in the West Central Montana backcountry is CONSIDERABLE. On all other terrain, steeper than 30 degrees the avalanche danger is MODERATE.
We have rescinded the avalanche warning associated with the recent winter storm; but there is still potential for human-triggered avalanches.
Good Morning, this is Dudley Improta with the West Central Montana avalanche advisory for January 31, 2014. This danger rating does not apply to operating ski areas and expires at midnight tonight. (Jan. 31).
Weather and Snowpack Analysis
This morning, west and northwest mountain winds are ranging from 5 to 17mph. Mountain temperatures are in the mid-twenties to mid-teens (F). The storm that began Tuesday evening deposited 1.5 to 2 feet of snow. The area continued to pick up snow last night and it is snowing lightly this morning. The storm came in warm and then temperatures went cold; this trend helped avalanche conditions be less sensitive.
Yesterday, observers in the field were finding a weak snow surface from the recent storm. Stability tests were showing low strength and moderate energy in the new snow. (snow profile Rattlesnakes) (snow profile Lost Trail Pass).
The Snow Bowl Patrol was able to trigger 10-15 inch soft slab avalanches with explosives on southwest couloirs. Travis Craft and I were able to ski-cut this same slab, on a northeast aspect in the Rattlesnake backcountry. (Photo_ human-triggered soft slab_Rattlesnakes) Observers at Lost Trail and the guides at Yurtski, in the Southern Swans, noted the same storm slab. All areas reported weak surface conditions with no discernible hard slab formation. And, although outside of our advisory area, observers at Lookout Pass noted the same conditions.
The surface hoar, that formed previous to the storm, was not the consistent weak layer for the new snow to fail on. We dug five pits in the Rattlesnakes and didn’t find it; but, the guides at Yurtski reported they were avoiding areas where they had seen it – not a bad idea.
This existing soft slab can be triggered, and could be a problem on very steep slopes. Keep in mind there is more snow, from last night, available to slide. The soft slab is probably 18 to 22 inches this morning.
The main avalanche concern, for now, is the storm slab on steep open slopes.
Weather Forecast and Avalanche Outlook
Another 4 inches, or so, of snow is forecast for today. Then, by Saturday, snowfall is predicted to taper off. Mountain clouds will hamper visibility in the high country. Winds should not be too bad (5-10mph) with high temperatures in the low twenties (F).
I would expect avalanche conditions to remain about the same through the weekend. Be aware of the potential to trigger the new snow on steep, open slopes at the higher elevations (>6000’).
Ski and ride safe! Have a great weekend.
The next avalanche advisory will be issued February 4.