Hatcher Pass Avalanche Forecast
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Today’s problems are persistent slab, dry loose, and wind slab. The most likely and largest consequence hazard today are loose dry avalanches in steep terrain. Persistent slabs are unlikely, and wind slabs are likely, but very small in size.
Coverage is still thin with 1-2 ½ feet of snow throughout the area. There are plenty of shallowly buried and exposed hazards. Even a small avalanche could result in compounded risk and consequence if swept into rocks.
For more information on this weeks weather, click the weather tab below.
Marmot looking tracked out. 11/18/20
Lower Presidents Ridge 11/18.
Dry Loose, Marmot, south facing slope, 4000′ 11/15
Wind Slab D1, Marmot, 4500′ NW 11/18
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 current snowpack has been slowly stabilizing over time, and the risk for human triggered persistent slab avalanches has decreased since the Election Dump on 11/7-8. It may be possible to human trigger small to large persistent slab avalanches in very isolated locations with previous wind loading, on all aspects, but primarily on west to north aspects, at upper elevations.
It’s been nine days since our last human triggered persistent slab avalanche. The faceted snow at the ground is generally buried underneath 1-2’ of snow. This will be found at all elevations and all aspects. Look at this observation on 11/15/20 to get a better idea of snowpack structure.
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 |
Cold temperatures have allowed surface snow to facet, and become weak sugary snow. This low-density snow will be capable of producing small dry Loose avalanches. Loose dry avalanches are probable on all aspects, on steep slopes 40° and steeper. Loose dry avalanches will travel fast and entrain enough volume to catch and carry a person. The main danger here is being swept into shallowly buried hazards.Users were observed triggering dry loose avalanches earlier in the week. Expect this problem to remain present throughout the week.
Dry Loose, Marmot, south facing slope, 4000′
Dry loose, Marmot, 4500′ NW
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 |
Small, fresh wind slabs, 2-3” thick, have formed recently in specific locations at the upper elevation near ridgelines on West to North aspects. These avalanches will be easily triggered on terrain 40° or steeper. Shooting cracks, stiffer snow overlying weaker snow, and smooth bulbous pillows, will be bulls-eye clues for this problem. Even a small wind slab could sweep you into dangerous, shallowly buried hazards.
Natural avalanches are unlikely.
Wind Slab D1, Marmot, 4500′ NW 11/18
Wind effect on Marmot ridge top. 11/18
No new precipitation this week.
Weather this week has been relatively stable until Wednesday(read more about winds below). This relatively cool clear weather, has allowed for snow surface to begin to facet. In some areas surface hoar 3mm in size has been observed. Temperatures at different elevations have been relatively uniform throughout the week. Starting in the teens at the beginning of the week, and increasing to the mid 20’s by Wednesday.
Winds from the east increased Wednesday with sustained winds up to 18 mphs and gust up to 27mph for 7 hours. These winds were able to transport low density surface snow and create some wind slabs.
NWS Rec Forecast here.
NWS point forecast here.
State Parks Snow Report and Motorized Access information here.
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Temp
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Rh
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Spd
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Gust
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Dir
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SWE
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SnoHt
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Min | 14 | 18 | 0 | 0 | N | 4.1 | 19 | ||||
Max | 28 | 52 | 8.2 | 15.3 | N | 4.3 | 21 | ||||
Average | 19.8 | 39 | 5.5 | 9.1 | – | 4.2 | 20 |