THIS SNOWPACK SUMMARY EXPIRED ON February 19, 2016 @ 11:00 pmSnowpack Summary published on February 19, 2016 @ 6:00 am
Issued by
Ben Bernall - Kootenai National Forest
Avalanche Character 1: 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.
With winds on the increase moving into the weekend and a forecast for more potential snow above 3,000' there will be more snow available for the formation of wind slabs, especially on leeward features above 5,000'. At upper elevations this snow will fall on a recently formed crust that will be an ideal sliding surface for avalanches.
BOTTOM LINE: This potential hazard will be on the rise going into the weekend with fresh snow and increasing winds in the forecast. Slides may be easily triggered on steep, wind loaded terrain features. As we move into next week and the sun comes out to warm the snow the avalanche hazard may also rise as well. Potential will exist for these slabs to release naturally due to decreases in strength or cornice failure. Best advice would be to avoid playing below these wind loaded slopes and practice safe travel habits during periods of rapid warming.
Avalanche Character 2: Loose Wet
Loose Wet avalanches occur when water is running through the snowpack, and release at or below the trigger point. Avoid very steep slopes and terrain traps such as cliffs, gullies, or tree wells. Exit avalanche terrain when you see pinwheels, roller balls, a slushy surface, or during rain-on-snow events.
Snotel sites across the Kootenai National Forest report above freezing temperatures since February 14th while precipitation continues with snow lines rising above 6,500'. These conditions combined with the accumulated mountain snowfall from the previous weekend have created ideal conditions for "loose wet" snow avalanches. As of today, February 18th, this hazard will be declining with temperatures on the decrease as a cold front moves into the region for the weekend. This cooling will temporarily strengthen the snowpack at elevations above the 4,000' mark through Monday. After that weather forecasts are hinting at warmer temperatures and the possibility of some sunshine moving into the Kootenai. This likely scenario will create an ideal environment for "loose wet" snow avalanches as the accumulated snow from the weekend begins to see sun and warmer air.
BOTTOM LINE: Pay attention to increasing temperatures as well as any changes in cloud cover or solar radiation that will rapidly weaken fresh surface snow. These loose, wet slides will be most likely to form on steep slopes exposed to the sun and below rock bands. As temperatures rise snowmobilers and skiers may find themselves easily cutting loose loose surface snow, especially where it has fallen on a recently formed crust layer.
Snowpack Discussion
Due to the fact that this forecast is issued once a week over a broad area there is alot of potential for variance in snow conditions and incoming weather. Best efforts are made to look at the predicted incoming weather and anticipate potential changes in snowpack stability. Having said this, we are entering that time of year when weather conditions and snowpack conditions can change rapidly. Backcountry users should get in the habit of not only checking the Snowpack Summary but also looking at predicted weather and NRCS SNOTEL data before they go out for the day. Checking these remote weather stations provides a good idea of recently fallen snow amounts as well as current and past temperature readings.
These weather stations may be found at the following location:
Weather and CURRENT CONDITIONS
weather summary
Backcountry Forecast from NWS Missoula issued:
410 AM MST Thu Feb 18 2016
DISCUSSION: A strong cold front will traverse the region today
impacting central Idaho early this morning and through western
Montana by early afternoon. Snow levels will drop as the front
passes with several inches of snow possible above 4000 feet.
Breezy westerly winds are also expected behind the front for both
mountains and valleys.
A cool and showery pattern will continue this evening through
Saturday with occasional mountain snow, especially this evening
and again early Saturday. Breezy westerly ridgetop winds are also
expected to continue through this period.
One last weather system will bring light snow on Monday, followed
by a relatively dry period for much of next week. Temperatures
will generally be above normal for the higher terrain and seasonable
in the valleys next week.
Kootenai:
--------------------------- 5000-7000 FT ----------------------------
Today Tonight FRI
Cloud Cover 95% 80% 85%
Hi/Lo Temps 35 to 39 25 to 30 33 to 38
Winds(mph) SW 20G44 SW 26G52 SW 14G35
Precip Chc 100 70 60
Precip Type tstms sno/shr snow
Liquid Amt 0.38 0.09 0.08
Snow Ratio(SLR) 15:1 14:1 14:1
Snow Amt(in) 2-5 1-2 1-2
Snow Level 4500 3000 3500
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.
