2/13: Natural and human triggered D1 avalanches were observed in keystone canyon.
2/12: A D3 avalanche at mile post 38 hit the Richardson highway and closed the road. Released on a south aspect in the upper elevation start zones, ~5500′, and stepped down around 4-4500′. Further DOT mitigation efforts on Three pigs and 40.5 mile produced no results.
2/11: Small avalanche observed on NW aspect of Dimond “promise land”, ~5500′ , R1-D1.5, wind loaded pocket just off ridge line.
-Several avalanches observed on steep benches below 2500′ on S aspect hippie ridge around MP 35. Only ran height of bench ~100′, but had long connected crowns suggesting these failed on a Persistent weak layer. Crowns ~2′ deep.
2/10: Skies cleared yesterday, from 46 mile to Thompson Pass very few natural avalanches were seen from the 27 inches of snow that fell from 2/8- 2/10.
2/8: Many full path avalanches were reported running around Valdez glacier lake.
2/6: 2 remote triggered avalanches on RFS at 1800-2000′.
Photo of 1st remote trigger listed
-Natural avalanches observed on south aspect at mile 40, ~1800′, 1-2 feet deep and ~100′ wide. SS-NL-R2-D1.5-O. These were triggered by small snow sluffs.
2/2: Numerous Small pockets of unsupported terrain released naturally in the tsaina valley below 2000′, 2′ deep.
1/27-1/30: Naturals were observed on RFS, N aspect ~6000′,
Avalanches were also observed on -40.5 mile, ~5000′ ,W aspect, 60 m crown
– 2 paths on Three Pigs, ~5000′, SE aspect, ran into the top 1/3 of aprons.
– 3 slides on Billy Mitchell ranging from 3000′-6000′, NW- N aspect. The most significant was on the upper bowl of cry babys, ~5000′, ~200 m crown, 1-2 meters deep.
1/23- Found fresh debris in a gully off point 3848′ behind the airport. D2, ran ~2000′.
~ 1/10- There have been several natural windslabs that have released in the Thompson Pass region:
-South slope of catchers mitt, near 27 mile icefall,~3500′, ~300m wide ,~3′ deep, ran 500′ HS-N-R3-D2.5. Photo shows extent of crown, which may have been bigger and is now filled in by wind transported snow.
– Gully Between Little and Big Oddessey, NW, 4000′, ~60 M wide, ~2-4′ crown, ran 1000′
-Averys, ~4000′, SW, ~70 M wide, ran ~1000′
1/11- Two natural wind slab avalanches observed at moonlight basin, 2500′-2800′, S aspect.
The first was on the small last roll before the road and had debris chunks up to 3′ deep “crown filled in by wind”, 200′ wide.
The second was in a cross loaded gully ~ 300′ above the road, with a crown up to ~10′ deep, ~100′ wide.
2/14: Clear skies, NE winds will ease and become moderate to light.
The Thompson Pass Mountain Forecast covers the mountains (above
1000 ft) surrounding Keystone Canyon through Thompson Pass to
This forecast is for use in snow safety activities and emergency
Temp at 1000` 20 F 12 F
Temp at 3000` 0-17 F 17 F
Chance of precip 0% 20%
(above 1000 FT) 0.00 in 0.04 in
(above 1000 FT) 0 in trace
Snow level sea level sea level
Wind 3000` ridges NE 15-25 mph NE 10-20 mph
Thompson Pass “DOT”
HN24W= total water received last 24 hours in inches
Thompson Pass weather history 19/20 season beginning 12/21 through 1/23. Click on links below to see full size image.
TP DEC 19
TP Jan 2020
TP through 2-13
Our area received 27 inches of snow 2/8-2/10, and an additional 4-8 inches on 2/12. This new snow is now being redistributed by strong NE winds.
Prolonged arctic temperatures in January have created a weak snowpack. Weaknesses in our snowpack are pronounced at old rain crusts where moisture was once concentrated, and has now formed facets. These rain crusts exist up to 3000′. Near surface facets were also formed in January and are spatially variable depending on their exposure to previous wind events.
Poor stability exists below 2500′ in the Thompson Pass region. Crust/Facet combos and near surface facets up to 2 mm exists that are now buried under 2-3 feet of snow. This layer is especially prominent in areas that were protected from strong wind in January and north of Thompson pass where temperatures were colder.
Prior to the 2/8 storm, stability improved as you went up in elevation and became good above 3000′ in certain areas. Strong outflow wind events in January did not allow near surface facets to be preserved in most locations. A very strong layer of wind affected snow exists under 2-3 feet of snow that fell beginning on the 26th of January. This wind affected snow is creating a bridging effect above a faceted mid and lower snowpack. These deep facets can still be reactive as seen by the D3 avalanche at 38 mile that closed the highway on 2/12. In alpine areas that were protected from January wind events, persistent weak layers will be present in the upper and mid snowpack that could still be reactive. In alpine areas this problem layer will be difficult to assess its distribution.
There is a high degree of spatial variability in our area. Careful snowpack assessment will necessary slope by slope. If you find good stability in one area don’t assume that the next place you go will be the same.
Forecast Confidence is Moderate.
Resolution is Moderate
Near surface facets found at 3000′ on Billy Mitchell 1/19. 2 MM grid.
There have been limited observations from interior locations due to low snow at lower elevations. Use caution if you travel in these areas.
If you see something in the mountains that could contribute to this forecast, leave a public observation. The more observations we receive, the better we can tune our forecast. If you would rather not post an observation publicly, feel free to send me an email at [email protected]
Be aware that the elevation bands have changed on our website. Low is now below 2000′, Mid is 2000-4000′ and high is 4000′ and above.
Send in your best mountain recreation photos to [email protected] so we can post a photo of the week!
Photo of the Week
Thanks to Spencer Byson for sending in this photo!
Ice Fest special announcement: The avalanche hazard is considerable in Keystone Canyon. A fragile snowpack exists in this location. Small human triggered and natural avalanches have been observed. Even small avalanches can knock you off your feet and sweep you downhill. Wear your beacon and avoid steep snow slopes with consequences below. See video in the observation section.
The avalanche hazard is considerable at all elevations. Strong outflow winds continue for our area and will easily redistribute the low density snow that fell on 2/12. Windslabs 1-2 feet deep will be present and could be reactive to human triggers on lee aspects (SE-NW). Watch out for pillowed snow surfaces, shooting cracks and hollow drum like snow, these are all indicators that you have found wind slab. Human triggered avalanches are possible today in areas that have received recent wind loading. Avalanches in the upper snowpack have the potential to step down into deeper layers of the snowpack and create very destructive avalanches. Avoid areas that are receiving active loading, cross loaded gullies and terrain traps.
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