January 21, 2014 Avalanche Advisory

The avalanche danger is now LOW in the west central Montana backcountry.  Natural and human-triggered avalanches are unlikely.

Although avalanche conditions are generally safe, you must consider that even under LOW avalanche danger conditions, it is possible to trigger an avalanche in isolated areas or on extreme terrain.

Good morning!  This is Steve Karkanen at the West Central Montana Avalanche Center with the avalanche advisory for Tuesday, January 21, 2014.  The avalanche danger rating expires at midnight tonight and it does not apply to operating ski areas.

 

Weather and Snowpack Analysis

A high pressure system has dominated our weather for well over a week now with warm daytime mountain temperatures, clear cold nights and a bit of wind.

This morning we have clear skies with the SNOTEL sites reporting temperatures in the teens and twenties. Winds are 20-30 mph from the west on Point Six.

At the Twin Lakes SNOTEL in the southern Bitterroot, snow depth at the beginning of the dry spell on January 13 was 86 inches. Today it is 71 inches.  Afternoon high temperatures well above freezing with overnight low temperatures dropping into the teens and low twenties have been recorded at the Twin Lakes, Hoodoo, Stuart and North Fork Jocko SNOTEL locations.  Lower elevations are staying cooler because of the inversion.

These moderate temperatures have promoted settlement and stabilization of the snowpack. 

The air mass is relatively dry and it has been windy at the higher elevations, so the window for surface hoar formation and growth is limited. It is quickly destroyed by wind or sun on the more exposed aspects but can be found in open shaded areas that are protected from the wind.  Buried surface hoar layers can be a big problem later on so it is important to note where you see it now.

The main avalanche issues to be aware of now are the wind slabs that formed over a week ago and wet, loose snow avalanches on sun exposed slopes steeper than 35 degrees. These wind slabs are widespread but have had a good chance to strengthen during the moderate temperatures of the past week.

Wet loose snow avalanches have been seen on the steeper southerly aspects in the past couple of days.  The wet snow avalanche activity involves the surface snow and is pretty easy to identify and manage.  Wind slabs are a much more difficult problem to identify and manage.

Large cornices formed during the last storm and can easily collapse under the weight of a person or sled. When they collapse, they usually fall on a wind slab and can trigger a deeper, more consequential avalanche.

Members of the Five Valleys Backcountry Ski Patrol were on Gash Point Sunday and found wind affected snow above treeline. They noted that many slopes have been cross loaded by the variable winds of the past few days but the stability was good.  The only failure they noted in their stability assessment was the surface wind slab failing about 15cm or 6 inches down.

Dudley was in the southern Swan range yesterday and reported spring-like conditions.  He noted several small wet slides on the southerly aspects and surface hoar development in protected areas.

 

Weather and Avalanche Forecast

The National Weather Service Office in Missoula is forecasting a blocking ridge of high pressure to dominate our weather. A weak upper level disturbance may bring very light precipitation to the mountains Wednesday and Thursday but high pressure will again take over through the weekend.

The snowpack will strengthen as moderate temperatures continue at higher elevations.  The problem with these dry clear periods is that near-surface faceting occurs.  Not a problem now, but once buried, we’ll likely be talking about these facets for the rest of the winter.

Our Submit an Observation form page is now up and running. Even though conditions seem quiet now, we still value hearing from you.  Every bit of information we receive helps.

 

Education and Events

This Wednesday evening from 5-8pm, The Kettlehouse is hosting a Community Unite Pint Nite for the West Central Montana Avalanche Foundation.  The location is the Northside Kettlehouse, 313 N 1st Street (above the Orange Street underpass) in Missoula.  Proceeds from this event help pay for avalanche advisories and education.  Come on down to hoist a pint and support the efforts of our non-profit!

There are still a couple of open slots for the Level 1 Avalanche classes next month in the Bitterroot. To sign up, contact the U of M Outdoor Program at 243-5172.  The class size is limited to 14 participants so call now.