Archived

Avalanche Forecast

Mar 14th, 2014–Mar 15th, 2014

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

2: Moderate

The avalanche danger rating below treeline will be moderate

Alpine

4: High

The avalanche danger rating in the alpine will be high

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

Regions: Glacier.

Deep reactive layers and another series of storms approaching deserve your attention. The snowpack this year is challenging, and has been surprising recreationalists and professionals alike. Be very cautious if you head into the backcountry.

Weather Forecast

A quick moving front will pass through the area today, bringing ~10cm with strong SW winds. A strong storm will arrive on Sat afternoon. Up to 20cm of snow is expected Sat, with moderate SW winds transporting snow and rapidly loading slopes. Another 16cm is expected Sunday. Freezing levels should stay below 1400m.

Snowpack Summary

Last weeks storm snow has settled over the March 2 crust down ~1m. Instabilities within the slab, and the crust, are becoming unreactive. The Feb 10 interface is down 1.5-2m and continues to react in snowpack tests. It has been most reactive recently on solar slopes, see below. Below this, the mid to lower snowpack is well settled.

Avalanche Summary

Yesterday, a group of ski tourers remotely triggered a size 2.5 avalanche from the thin rocky ridge at 2650. The avalanche failed over 30m away on a S aspect. It was ~1m deep, likely failing on the Feb 10 PWL, and ran over 400m. With the recent sunshine, numerous natural solar triggered avalanches to size 3 have been occurring daily.

Confidence

Timing, track, or intensity of incoming weather system is uncertain

Avalanche Problems

Persistent Slabs

We are expecting over 50cm of snow this weekend, with strong westerly winds. This will rapidly load the persistent weak layer down 1.5-2m. This layer continues to be reactive and surprise people throughout the region, producing impressive avalanches.

Be aware of thin areas that may propogate to deeper instabilites.Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2 - 4

Storm Slabs

Lots of new snow, with wind, through the weekend will form a new storm slab. This slab will likely be most reactive where it overlies suncrust, but will also bury small surface hoar. If triggered, this slab may also step down deeper.

Choose conservative lines and watch for clues of instability.Minimize exposure during periods of heavy loading from new snow, wind.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 2 - 3