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Avalanche Bulletin for 3/13
The Hatcher Pass Avalanche Center has issued a Special Avalanche Bulletin.
* Affected Area…For the Hatcher Pass State Park and Hatcher Pass surrounding areas including: Arkose Ridge, 16 mile, Gold Mint, Archangel, Marmot, IM Bowl, to Hatcher Pass.
* Avalanche Danger… Avalanche Danger is rated CONSIDERABLE. Significant rapid snowfall of 36” on 3/7-3/9 contributed to an avalanche cycle with a weak layer that continues to persist. An avalanche fatality occurred at low elevation on a S aspect on 3/9. On 3/12, a large avalanche on Marmot gully 3 crossed the road, closing the road. Hatcher Pass road will be closed at mile 12, on March 13th for avalanche mitigation.
Precautionary/Preparedness Actions… Careful snowpack evaluation, cautious route-finding and conservative decision-making skills are necessary for travel in the backcountry.
Similar avalanche danger may exist at locations outside the coverage area of any avalanche center.
Signal Word | Size (D scale) | Simple Descriptor |
Small | 1 | Unlikely to bury a person |
Large | 2 | Can bury a person |
Very Large | 3 | Can destroy a house |
Historic | 4 & 5 | Can destroy part or all of a village |
You can get away with skiing/riding all kinds of terrain right now BUT triggering a very large avalanche is still possible, as we just saw with the one that hit the road. A large avalanche problem still exists with old weak layers lingers in the snowpack. The problem is challenging to find and stubborn to trigger in most locations. We saw evidence of this problem Thursday with a few recent avalanches. One avalanche is believed to have been remotely triggered, on a S aspect at approx: 3500 ft. in Marmot gully#3( lookers right of the standard Marmot uptrack). This avalanche was large and crossed the road by 100 yards, and closed the road.
A second avalanche shortly after was reported on a W aspect of President’s ridge at a similar elevation. Trigger is unknown.
Snomachiners also reported a remotely triggered small slab on a S aspect at 2600′ near Idaho Peak. Although further away up Buffalo Mine, another incident occurred with a snomachine remotely triggered large slab avalanche.
We suspect that this persistent slab problem is easier to detect at low and mid elevation, on shallower slopes, most likely SE to W aspects where widespread whumping continues to be observed. It will be more challenging, but not impossible, to trigger this slab on most leeward aspects where the January facets are buried 3-5 feet deep.
Spring time temps are beginning to warm up and affect snow surfaces. If we see a rapid warm up, expect avalanche danger to increase.