Hatcher Pass Avalanche Forecast
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The avalanche danger is considerable at all elevations.
Overnight the forecast area has received 10-12 inches of new snow and .9″ of SWE.
Human-triggered persistent slab avalanches 3-5 feet thick will be likely at all elevations and all aspects on slopes 30º and steeper. These avalanches will be large in size.
Human-triggered loose dry avalanches 10-12 inches deep will be likely at all elevations and on all aspects. On slopes 40º and steeper. These avalanches will be small in size.
Natural avalanches are possible.
Since 12/12 Hatcher Pass has received 38 inches of snow and 3.4 inches of SWE.
There will be an end to all this snowfall! The current storm will end this afternoon, expect new snow to taper off, temperatures to drop and the sky to clear.
Numerous large natural avalanches were observed on Wednesday 12/14. There were likely more avalanches that occurred but poor weather inhibited our ability to see many locations.
Stairstep NW 3200′. D2 persistent slab avalanche. 12/13/22
Arkose 1 slide path. West 3600′ D2+ persistent slab avalanche. 12/13/22
Punk Spine, West 4100′ D2 persistent slab avalanche. 12/13/22
Government Peak area, East 4200′. D2 persistent slab avalanche on saddle between Peak 4600′ and Government. 12/13/22
Sunny Side of Hatch, East 4200′. D2+ persistent slab avalanches. 12/13/22
Avalanches not pictured:
Idaho Peak South 2700-3200′ several D2 persistent slab avalanches.
Arkose Waterfall slide path, West 3500′ D2 persistent slab avalanches.
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 |
The 39 inches of new snow that have fallen this week, has stressed weak faceted snow at the bottom of the snowpack. Human-triggered persistent slab avalanches will be likely at all elevations on all aspects, on slopes 30 degrees and steeper. Natural avalanches are possible. These avalanches will be large and capable of causing entire slopes to avalanche.
Lower punk spines NW 2400′ D2 persistent slab slab avalanche. 12/13/22
While in the field yesterday forecasters observed widespread natural avalanches that failed at the ground. These avalanches occurred at all elevations and all aspects. The snowpack still has flawed structure and will need time to adjust to all the new snow that fell over the last week.
As the weak sugary faceted snow at the ground gets buried deeper avalanches will be harder to trigger but the consequences of an avalanche will grow. Any persistent slab avalanche that is triggered will be large enough to bury, injure or kill a person.
The persistent slab problem is now buried deep enough that formal stability tests may not provide reliable information. It will be more important to identify the structure and determine if cohesive snow is sitting above weak faceted snow at the ground. Due to the depth of the weak layer, shooting cracks or collapsing may not be observed before triggering an avalanche.
Snow stake at 4am this morning.
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 |
The 10-12” of new snow that fell overnight will be capable of producing small loose dry avalanches. Human-triggered loose dry avalanches are likely on slopes over 40º. Natural avalanches are possible. The drizzle crust that formed on December 13th will act as a bed surface for loose dry avalanches.
This drizzle crust will be found at lower and mid elevations, forecasters have yet to verify how high in elevation this crust formed.
Hand pits and other traveling tests will be good tools to identify this avalanche problem.