Stability test performed on February 13th revealed a stable snowpack below 7,000'. The warm temps and rain that saturated the snowpack and created very touchy avalanche conditions late last week have now cooled off and locked the upper snowpack together. If there is a place where one may find poor stability it will be on aspects that are taking on mid-day solar radiation. South and westerly aspects are harboring weak snow still at the base of the snow pack, intense sun may be enough to trigger these deeper weaknesses.
Best travel advice would be to avoid steep, south and westerly aspects as the sun and forecasted high temperatures begin to warm these slopes. Be on the lookout for loose wet slides and small rollers as this will be your warning sign to move into shaded terrain.
This problem is limited to the highest peaks of the Cabinet Wilderness above 7,000' where last weeks mountain rain event fell as snow. These upper elevations were under high winds and recieved heavy amounts of snow that are likely to be very touchy at this point. If you are venturing into the Eastern Cabinets this week play close attention to changing conditions as you climb into the upper elevations. Use the ridge lines for travel and be especially alert to what is overhead as the sun comes out and brings the daytime high temperatures well above the freezing mark.
On Monday February 13th I traveled to the area around the Bear Mountain Snotel site and the Twin Peaks vicinity. I was pleasantly surprised to find over 6" on light new snow on top of the firm rain crust that developed during last weeks rain event. We had very stable pit results on a shaded north-westerly aspect. We observed multiple avalanche crowns on Benning and Twin Peaks that appeared to have released the prior week. One crown line on the backside of Benning appeared to have traveled across multiple aspecst and stepped down to the ground on rocky-south facing terrain. Unfortunately my pictures are completely blurred!
Backcountry Forecast from NWS Missoula issued:
400 AM MST Tue Feb 14 2017
High pressure will continue to provide strong temperature
inversions with above freezing temperatures up to around 8000
feet through Wednesday. Cold valley temperatures will warm up 20
to 30 degrees by the afternoons. The ridge will begin to break
down on Wednesday bringing an increasing chance for mountain rain
with freezing rain in the valleys into Thursday morning. Snow
levels will fall by Thursday night.
--------------------------- 5000-7000 FT ----------------------------
Today Tonight Wed
Cloud Cover 10% 15% 50%
Hi/Lo Temps 37 to 43 22 to 26 36 to 41
Winds(mph) SW 6 SW 8 S 8G18
Precip Chc 0 0 30
Precip Type none none snow
Liquid Amt 0.00 0.00 0.01
Snow Ratio(SLR) 0 0 15:1
Snow Amt(in) 0 0 0
Snow Level 7500 7000 5000
This advisory applies only to backcountry areas outside established ski area boundaries. This advisory describes general avalanche conditions and local variations always occur. This advisory expires midnight on the posted day unless otherwise noted. The information in this advisory is provided by the USDA Forest Service who is solely responsible for its content.
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