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Archived

Avalanche Forecast

Mar 8th, 2017–Mar 9th, 2017
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Glacier.

Variability in the storm slab bond to old snow surfaces is making snow stability harder to predict.  Be alert to signs of snowpack instability.

Weather Forecast

Sporadic bands of flurries will travel through the park today bringing light precipitation.  Ridge top winds will shift from southerly to westerly and will remain in the moderate range.  There will be a break in the precipitation tonight with more snow on the way Thursday.

Snowpack Summary

60cm+ of storm snow in the past week which in some locations is bonding well and other locations is still susceptible to human triggering. The storm snow has been accompanied by moderate to strong S winds aiding in the formation of storm slabs through all three elevation bands. The mid February persistent weak layers down 70cm+ is still a concern.

Avalanche Summary

Two new slides in the highway corridor to size 2.5. A flight into the NE ridge of Ursus Minor showed widespread avalanche activity during the storm cycle with size 3 slides off the north sides of 8812 and Ursus Major. The most interesting slide was a soft slab at treeline, 500m wide, 30-40cm deep and ran 200-300m and likely occurred on Monday.

Confidence

Intensity of incoming weather systems is uncertain

Avalanche Problems

Storm Slabs

Storm slab formation has been widespread and through all elevations. However its susceptibility to human triggering is highly variable. The bond to the old snow surface of crusts and facets is questionable.
The storm slab may be more sensitive to human triggering on solar aspects where it sits on sun crustIf triggered the storm slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 3

Wind Slabs

Moderate to strong S winds have continued to transport snow at upper elevations forming soft slabs along the immediate lee of ridges and cross winded features.  These may be sensitive to human triggering.
Upper elevation north through east aspects should harbor wind slab formed over the past week.The new snow will require several days to settle and stabilize.

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

Elevations: Alpine.

Likelihood: Likely

Expected Size: 1 - 3