January 13, 2012 Avalanche Advisory

LOW to MODERATE Avalanche danger conditions exist in the west central Montana Backcountry.

Good morning, this is Steve Karkanen with the west central Montana avalanche center’s backcountry avalanche advisory for Friday January 13, 2012.

Above 7000 feet on steep wind loaded terrain the avalanche danger is MODERATE, natural avalanches are unlikely and human triggered avalanches are possible.  On all other backcountry terrain the avalanche danger is LOW, natural and human triggered avalanches are unlikely.

If you know where and what to look for, you can probably find a few pockets where the avalanche danger is CONSIDERABLE, but the overall condition on slopes steeper than 35 degrees is MODERATE.  There are heightened avalanche conditions on terrain features such as steep wind loaded pockets, slope roll-overs and in places where the snowpack is shallow.

Weather and Snowpack Analysis

Mostly mild weather prevailed this week with a short burst of precipitation Tuesday afternoon and early Wednesday. SNOTEL sites picked up an average of 6 to 8 inches of new snow that covered a rime crust that was laid down over a broad area last Sunday.

All our observers report a strengthening snowpack with the weakest layer being the interface of the new snow and the rime crust.  The more deeply buried faceted layers we have been describing are continuing to slowly gain strength.  Stability testing yields failures at these layers but only when a great deal of force is applied.  In some specific cases, we do get fracture propagation of the thick slab on wind loaded north aspects and on slope convexities.

There is still enough weakness in the snow structure to be cautious. The avalanche danger will sky rocket the next time it snows heavily.

Weather Forecast and Avalanche Outlook

The Missoula Office of the National Weather Service is forecasting a cold front to move through the area Saturday night. Windy conditions and snow with the front will leave a few inches of snow. Temperatures Sunday will be much cooler with moderate to heavy snow.

A much wetter pattern develops Tuesday through the rest of the week.  Expect a return to winter with a vengeance.  Although the current snowpack conditions are improving over time, a quick heavy load will again tip the balance back into an unstable situation. This next storm will need to be closely monitored.

Expect conditions to remain similar with slow improvement until the area again receives significant snow.

I will issue the next advisory on Martin Luther King Day.

We have been seeing a few excellent reports from many of you.  These are very helpful and help us provide a better avalanche safety product for you.  You can easily submit this information on our website or just send us a quick note at [email protected]

On January 18 the Kettlehouse is sponsoring a Community Unite Pint Night with the proceeds benefiting missoulaavalanche.org. Check out our home page for more information.