THIS SNOWPACK SUMMARY EXPIRED ON February 15, 2017 @ 1:00 amSnowpack Summary published on February 14, 2017 @ 8:00 am
Issued by
Ben Bernall - Kootenai National Forest
Avalanche Character 1: Persistent Slab
Persistent Slab avalanches can be triggered days to weeks after the last storm. They often propagate across and beyond terrain features that would otherwise confine Wind and Storm Slab avalanches. In some cases they can be triggered remotely, from low-angle terrain or adjacent slopes. Give yourself a wide safety buffer to address the uncertainty.
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.
Avalanche Character 2: Wind Slab
Wind Slab avalanches release naturally during wind events and can be triggered for up to a week after a wind event. They form in lee and cross-loaded terrain features. Avoid them by sticking to wind sheltered or wind scoured areas.
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.
Snowpack Discussion
Join us on Wednesday night at 6 P.M. in Libby for a 1-2 hour avalanche awareness presentation. It will be held at the Libby Middle High School Library. Hope to see you there!
For additional info email me at bbernall@fs.fed.us
recent observations
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!
Weather and CURRENT CONDITIONS
weather summary
Backcountry Forecast from NWS Missoula issued:
400 AM MST Tue Feb 14 2017
DISCUSSION:
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.
Kootenai:
--------------------------- 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
Disclaimer
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.
