Avalanche Advisory: Friday - Feb 5, 2021

THIS AVALANCHE ADVISORY EXPIRED ON February 6, 2021 @ 6:19 am
Avalanche Advisory published on February 5, 2021 @ 6:19 am
Issued by Steve Mace - ESAC

MODERATE avalanche danger persists at all elevations today. Evaluate snow and terrain carefully and use terrain choice to mitigate your exposure to potential persistent slab avalanches. Wind slabs of varying size and sensitivity will also be possible to find on all aspects near and above treeline.

Thank you to everyone who was able to make it to our second virtual education event on the evening of February 3rd, focusing on Avalanche awareness, How to use the advisory, and a discussion about the current state of the snowpack. This event was recorded and is available to view on our YouTube page!

2. Moderate

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Above Treeline
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

2. Moderate

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Near Treeline
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

2. Moderate

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Below Treeline
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
    Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
Avalanche Problem 1: Persistent Slab
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A robust slab is now resting on a weak and unconsolidated base in many areas throughout the range, particularly in the northern part of the forecast area. Northerly and easterly aspects are of greatest concern however we are not ruling out the broader distribution range of W-N-E-SE. Persistent Slab problems challenge our patience. Managing this problem requires extensive evaluation and deliberate terrain choice. Avalanches breaking on these lower weak layers have the potential to be large and destructive. Don’t be afraid to dig in and get a look at the lower layers of the snowpack to see if old snow is present in the areas you want to travel. Remember that persistent slab avalanches often propagate across and beyond terrain features that would otherwise confine surface instabilities such as wind or storm slab and in some cases persistent slab avalanches can be remotely triggered from adjacent slopes. Give yourself a wide safety margin, be wary of hazards that may reside above you, and use terrain choice to limit your exposure.

Avalanche Problem 2: Wind Slab
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Wind slabs will vary in size and sensitivity today and may be present on all aspects near and above treeline. Lingering wind slabs on northerly and easterly terrain have the potential to be quite large and may still be reactive to human triggers. Much of our alpine snowpack was ravaged by extreme winds on February 3rd leaving very little transportable snow left in exposed terrain. However, as our current northerly winds increase in speed today, fresh wind deposits may accumulate in isolated areas in more southerly and westerly terrain as well. Exposed areas and leeward catchment zones near and above treeline deserve elevated caution. Large drifts, recent cornice growth, and uneven snow surfaces are all clues that indicate nearby wind deposits. Do your own localized assessments and be suspect of terrain features that encourage drifting such as the leeward sides of ridgelines, gully features, and cross-loaded depressions.

advisory discussion

As we enter a period of quiet weather it will be important to remain vigilant. Surface warming resulting from sunny skies and warming temperatures could result in isolated loose wet activity or aid in loosening cornice features and small panels of wind slab.  While our warm climate should be a beneficial thing for stability in the long run it will take some time. Several large avalanches have been reported over the past few days demonstrating the destructive power of our current snowpack. Our current weather pattern will be a powerful draw to the backcountry enthusiast however, objective evaluation and deliberate terrain choice remain prudent.

recent observations
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2/04 – Mammoth area- Large avalanche, Hollywood bowl, Mammoth Lakes basin

2/04 – Mammoth area- Sherwin ridge, cornice collapse

2/04 – Mammoth area- Sherwin ridge, snowpack conditions

2/04 – Mammoth area- Sherwin ridge, variable surface conditions

2/04 – Mammoth area- Snow structure, MMSA backcountry

2/04 –Mammoth Area- Snow conditions, No name peak

2/04 – Mammoth area- Large avalanche, Bloody mtn

2/04 –Convict area- natural wind slab avalanche, Mono Jim Peak

2/04- Convict to McGee- Snow conditions

2/04- June Lake area- Snow conditions in the June Backcountry

2/04 -Rock creek- Snow conditions

2/04- Bishop area- Variable surface conditions, Habeggers

2/03 – Bishop Area –Table Mountain – Bardini Cyn – Stripping winds

2/03 – Rock Creek –Collapsing of snowpack in trees

2/03 – Mammoth Area- High winds and ground transport of snow

Weather and CURRENT CONDITIONS
weather summary

Expect Sunny skies and mild temperatures today. Temperatures are expected to be above freezing today with highs in the low to mid 40°s at lower elevations and in the mid 30°s above 10,000’. Expect winds to continue out of the N today, increasing to moderate- strong speeds with ridgetop gusts expected around 70 mph.

Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 8,000 ft. to 10,000 ft.
Friday Friday Night Saturday
Weather: Sunny. Clear. Sunny.
Temperatures: 37 to 45. deg. F. 21 to 27. deg. F. 40 to 48. deg. F.
Mid Slope Winds: East to northeast 10 to 20 mph with gusts to 35 mph. North to northeast 10 to 20 mph with gusts to 40 mph in the evening becoming light. Light winds becoming northwest around 15 mph in the afternoon. Gusts up to 30 mph.
Expected snowfall: 0 in. 0 in. 0 in.
Over 10,000 ft.
Friday Friday Night Saturday
Weather: Sunny. Clear. Sunny.
Temperatures: 31 to 37. deg. F. 19 to 25. deg. F. 33 to 39. deg. F.
Ridge Top Winds: North to northeast 25 to 40 mph shifting to the northwest in the afternoon. Gusts up to 70 mph. Northwest 15 to 30 mph. Gusts up to 70 mph in the evening. Northwest 15 to 25 mph with gusts to 35 mph.
Expected snowfall: 0 in. 0 in. 0 in.
Disclaimer
This Avalanche Advisory is designed to generally describe avalanche conditions where local variations always occur. This product only applies to backcountry areas located outside established ski area boundaries. The information in this Avalanche Advisory is provided by the Eastern Sierra Avalanche Center, who is solely responsible for its content.

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