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Archived

Avalanche Forecast

Dec 7th, 2015–Dec 8th, 2015
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
4: High
The avalanche danger rating at treeline will be high
Below Treeline
4: High
The avalanche danger rating below treeline will be high
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
4: High
The avalanche danger rating at treeline will be high
Below Treeline
4: High
The avalanche danger rating below treeline will be high

Regions: Glacier.

We are at the touchy upper end of Considerable trending toward High avalanche danger.  Conservative route selection is paramount.

Weather Forecast

A large pulse of warm precipitation is coming at us from the SW bringing upwards of 40mm of precipitation by Tuesday afternoon.  Freezing levels are expected to rise to over the 2000m level. 

Snowpack Summary

We are closing in on critical loading on the weak Dec 2 surface hoar layer down anywhere from 25-50cm. The building storm slab will overload this layer resulting in a widespread avalanche cycle. Look for a steadily increasing avalanche danger.

Avalanche Summary

Natural avalanches and skier triggered slides in the 1-1.5 size range were reported yesterday. Numerous avalanches were recorded in the highway corridor. These slides all appeared to be releasing on the Dec 2nd surface hoar layer. Field tests on a SE aspect at 2000m on Grizzly Shoulder gave a Rutch block 3 full block 50cm down on a sun crust.

Confidence

Timing of incoming weather systems is uncertain

Avalanche Problems

Storm Slabs

The Dec 2nd surface hoar layer is reaching critical overloading by the storm slab. Expect the storm slab to be reactive to both human and natural triggering.
Minimize overhead exposure during periods of heavy loading from new snow, wind.Watch for whumpfing, hollow sounds, and shooting cracks.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 3

Wind Slabs

Windloading has formed windslabs on alpine and treeline northerly aspects.  In some locations these slabs will be resting on the Dec 2nd surface hoar layer and will be sensitive to human triggering.
Use caution in lee areas. Recent wind loading have created wind slabs.Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: North, North East, East, South East.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 3