The Bottom Line: The hazard rating above treeline is CONSIDERABLE. There is a buried weak layer; it is widespread. This SCARY problem could persist into the springtime....
Problem 1: Persistent Slab
Distribution: All aspects above treeline. Size: Large-very large. Likelihood: likely. Sensitivity: reactive.
Description: Above 3000', natural avalanches up to 4' have been reported, particularly on north aspects. There is a widespread buried weak layer (surface hoar), that is quite reactive. Snowpit stability tests are reading with FALSE positives - such as ECTX, because the buried weak layer is so deep. Evaluate ALL avalanche terrain carefully, choose mellower terrain, AND consciously choose group spacing. If SNOW is the Question, Terrain is the Answer. Now is NOT the time to choose large terrain features or objectives.
Problem 2: Wind Slabs
Distribution: Above 2000', primarily on southerly aspects. Size: small+. Likelihood: possible. Sensitivity: stubborn.
Description: On 1/31 the north wind picked up and is building new wind slabs. Wind slabs can be stiff and stubborn to trigger and can release higher and wider than expected. Use caution in wind-loaded terrain near ridgelines or below cornice-like features. Wind slabs often present themselves with stiff-hollow-drum-like sounding slabs.
Problem 3: Glide Avalanches.
There are open cracks from the port to 42 mile between 3500-4000' on multiple aspects and on January 8th there was a full release near mile 31 and there were multiple full releases on the Deserted glacier between Jan 12-18. It is important to remember glide cracks can release at any time and are not associated with human triggers. New snowfall is covering up these gaping, crevasse-like features so use caution particularly when traveling in FLAT LIGHT. The best way to manage this problem is to limit (AKA avoid) travel underneath and beside them.
The current list of known open glides cracks from West to East:
On Jan 30th multiple remote triggered and natural avalanches were observed between Nicks (gulley 3) and RFS. Crown heights were up to 4 FEET, above 3000' on north and south facing aspects. Reports continue to CONFIRM surface hoar was the weak layer, This layer is widespread and was buried on Jan 23.
On Jan 26th, a remotely triggered soft slab avalanche was triggered near the Tonsina Glacier, in Don valley. D2, 1-3' crown, 500' wide. There were also several natural D1 soft slab avalanches from Jan 25-26.
In the Tsaina valley numerous small wet loose avalanches ran on Jan 26th.
On Jan 26th multiple small wet loose avalanches were reported on steep south facing, low elevation terrain near Valdez.
On Jan 25th, a small natural soft slab was reported in very steep terrain low in Loveland Basin.
Please share your field observations including signs of stable snow HERE.
The most recent NWS rec Forecast can be found HERE:
417 AM AKST Sat Feb 2 2019
The Thompson Pass Mountain Forecast covers the mountains (above
1000 ft) surrounding Keystone Canyon through Thompson Pass to
Temp at 1000` 8 F -5- 1 F
Temp at 3000` 11-17 F 20 F
Chance of precip 20% 40%
(above 1000 FT) 0.02 in 0.04 in
(above 1000 FT) trace trace
Snow level sea level sea level
Wind 3000` ridges NE 6-23 mph NE 3-20 mph
SNOWPACK BIG PICTURE: The older snowpack is quite stable (good strength and structure). Any new snow since Jan 23 is likely to be sitting on widespread surface hoar and is currently UNSTABLE. Above 3500' there is up to 4' of new slabs sitting on these this week layer.
Recent snowpack history, from top to bottom:
Jan 30-Feb 1: Natural avalanche cycle on all aspects above 3000', up to size D2.5. Most ran on buried surface hoar.
Jan 28-30: 2" SWE in Valdez, moderate winds, freezing level 1000'.
Jan 23-25: Multiple days of warm and wet with periods of rain up to 2500'.
Jan 13-22: Mostly clear and dry with light to moderate north winds. Widespread Surface Hoar growth and Near Surface Faceting.
Jan 12-13: 3-10" of new snow with little wind.
Jan 4-12: was VERY cold and dry: moderate winds and wind chill reaching -50F. Pockets of surface hoar and widespread near surface faceting.
Dec 30-Jan 3: The New Year's Eve storm brought nearly 2.5" of SWE to Valdez and almost another 1" (SWE) on the 2-3rd of January. The rain line was 1200' during the Jan 2-3 storm, forming a 1-3" crust locking up all the snow beneath it. These storms accumulated over 3' above 2000' near Thompson Pass. Both of these storms had little wind.
Above 4000' the snowpack averages well over 300cm deep and has good strength and structure (few lemons). Below 4000', the snowpack is significantly shallower and has old problem layers that are bonding well (rounding) and currently dormant: facet-crust combos and BASEL facets (all the way to sea level).
If you get out riding, please send in an observation.
Do a rescue practice with your partners. Always carry a beacon, shovel, and probe, and KNOW HOW TO USE THEM.
Practice good risk management, which means only expose one person at a time to slopes 30 degrees and steeper, make group communication and unanimous decision making a priority, and choose your terrain wisely: eliminating unnecessary exposure and planning out your safe zones and escape routes.
The current hazard rating is CONSIDERABLE above 2000'. There is a buried weak layer that is producing large unpredictable avalanches. More info is available by clicking FULL FORECAST below.
Please share your field observations HERE.
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