Martin Luther King Day Avalanche Advisory

MODERATE avalanche danger exists above 7000 feet on wind loaded terrain steeper than 35 degrees, LOW avalanche danger exists on all other backcountry terrain in west central Montana.

Under MODERATE avalanche conditions it is possible to trigger small avalanches in specific areas or large avalanches in isolated areas.  These locations are any open  slope steeper than 35 degrees and the higher east to north facing recently wind loaded terrain.

A return to winter conditions with heavy snow will raise concern about the stability of our mountain snowpack.

Hello!  This is Steve Karkanen with the West Central Montana Avalanche Center’s backcountry avalanche advisory for Monday January 16, 2012.

 

Weather and Snowpack Analysis

Since last Friday high elevation locations were blasted by high west-southwest winds.  The Point Six RAWS station recorded average wind speeds in the 30mph range with gusts to 55mph.  Large snow plumes were evident from many valley locations Saturday as wind slabs formed on the east to north aspects.  The wind dropped off Sunday morning and turned from the northwest.

Only minimal amounts of snow have been recorded by SNOTEL sites this morning and temperatures are in the single digits.

The overall stability continues to improve with time with the primary concern being these recently formed wind slabs.  Although conditions are improving, the structure of this years snowpack will not be able to support a heavy load.

 

Weather Forecast and Avalanche Outlook

The much anticipated winter storm is about to arrive.  Winter storm watches have been posted for all of western Montana with the first of a series of storms expected Tuesday.  Cold temperatures and an increase in precipitation will be the lead in today then we can expect heavy snow and high winds.

BACKCOUNTRY FORECAST FOR WESTERN MONTANA AND NORTH CENTRAL IDAHO

NATIONAL WEATHER SERVICE MISSOULA MT 220 PM MST SUN JAN 15 2012

HEAVY MOUNTAIN SNOW AND LIQUID WATER CONTENT THIS WEEK…

DISCUSSION…SNOW SHOWERS THROUGH MONDAY AFTERNOON ARE EXPECTED TO PRODUCE ACCUMULATING SNOW. A STRONG AND WET WESTERLY FLOW WILL SET UP OVER THE NORTHERN ROCKIES TUESDAY AND PERSIST THROUGH SATURDAY. EXPECT SEVERAL FEET OF SNOW (TOTAL 4-8 FEET) THROUGH THE ENTIRE PERIOD.

For now we’re taking a wait and see approach to this developing scenario.  There will be two major considerations with this storm.

 

  1. Heavy snowfall will quickly overload the most recent buried surface hoar layer which sits on a fine zipper crust 15-20cm from the surface.
  2. The initial storm will be cold then on Thursday a much stronger and warmer system will override cold air in the valleys bringing the possibility of rain to valley locations and a heavy wet snow in the mountains.  This scenario will make conditions very dangerous on any slope steeper than 30 degrees.

The bottom line is that you can expect to see very dangerous avalanche conditions begin to develop as soon as the mountains receive about a foot of snow.  The weather service is forecasting several feet so it should be a no-brainer that it will be dangerous out there.

We will be watching this closely and will update this information as needed.

Dudley will issue the next regular advisory Friday, January 20.

This Wednesday evening the Northside Kettle House is sponsoring a Community Unite Pint Night with the proceeds going to missoulaavalanche.org.  Come on out and celebrate the snow, win some cool prizes and help support our efforts to keep you from getting buried.  See you there!