Avalanche Advisory: Friday - Mar 27, 2020

THIS AVALANCHE ADVISORY EXPIRED ON March 28, 2020 @ 6:51 am
Avalanche Advisory published on March 27, 2020 @ 6:51 am
Issued by Chris Engelhardt - Eastern Sierra Avalanche Center

MODERATE avalanche danger exists above and near treeline Friday for Wind Slab and New Snow instabilities on ALL ASPECTS with a focus on the Northerly-Easterly slopes. LOW danger exists below treeline. There was a remote skier triggered avalanche on an East aspect at 9800ft yesterday in the Mammoth Lakes Basin. Additionally, pay attention for potential warming or greenhouse effects destabilizing new snow deposits on sunny aspects. Use wise terrain choice today to avoid fresh cornice, convex and unsupported slopes, or riding over terrain traps. Human triggered avalanches are possible, so evaluate snow and terrain carefully today.

*Given the current situation, an injury at this time requiring medical attention could result in serious consequences for yourself and others. Limit your risks!  

*To comply with the Inyo County Sheriff’s Office request, ESAC’s forecasts and field work are now limited to Mono County.

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.

1. Low

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Below Treeline
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
    Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
Avalanche Problem 1: Wind Slab
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The Mammoth area is of most concern where 10-12” of new snow was found in most local areas yesterday with an additional 1-4” snow falling in the evening and last night with moderate NE winds blowing up high in the northern part of the forecast zone. Be on the lookout for Wind Slab on NW-N-NE-E-SE aspects and also pay attention for potential cross loading on the sunnier aspects with overnight winds shifting to NE-NW. Be observant for cornices, cross loaded drifts and pillows of snow established on terrain features such as slopes adjacent to ridgeline, cliff bands and convex rollovers. Shooting cracks, audible whoompfing or panels of firmer wind effected snow resting on top of looser, less cohesive snow will be good indicators that wind slab is present. Be observant of overhead hazards, and plan your route accordingly if you’re travelling in terrain where avalanches may impact you from above. Maintain good travel protocols, such as traveling slopes one at a time (both up and down), anchoring up in safe spots, and maintaining good communication and consistent group plans and routes.

advisory discussion

There was rapid settlement yesterday with the new light snow becoming increasingly heavy, cohesive and viscous on East aspects that were receiving lots of solar input…even by mid-morning. This could have been a contributing factor to the skier triggered slide on an East aspect above the traditional approach to Red Cone at 9800ft yesterday. This incident is a poignant reminder to take pause and remember to always follow your fundamental travel protocols and to constantly re-evaluate conditions as you travel both up and down in the winter mountain environment.

Loose Dry sloughing should still be on the radar in steep, tight and confined terrain and in relation to exposure. Surface sloughing was observed throughout the Mammoth and VA lakes area yesterday and a cold night last night likely pulled more moisture from surface snow.

This has not been the winter, nor the time right now with all we are dealing with to risk serious injury by skiing with abandon… especially regarding the overall thin and obstacle ridden conditions we have dealt with all season.

It is also important to practice social distancing at all times, from travelling in seperate cars going to the trailhead, and keeping at least 6 feet between individuals while skinning and re-grouping.  We all need to do our part in preventing the spread of this Corona Virus!  

Weather and CURRENT CONDITIONS
weather summary

A sunny day transitioning to partly cloudy skies is on tap for today with light to moderate NW winds for the higher elevations. Temperatures will reach the mid 30sF for the lower elevations while 17-26F will be in store above 10000ft. A return to more unsettled weather with chance of snow and mostly cloudy conditions for Saturday.

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 then becoming partly cloudy. Snow levels below 7000 feet. Chance of precipitation is 0%. Partly cloudy. Snow levels below 7000 feet. Chance of precipitation is 0%. Mostly cloudy. Chance of snow in the afternoon. Snow levels below 7000 feet. Chance of precipitation is 30%.
Temperatures: 27 to 35. deg. F. 11 to 17. deg. F. 29 to 37. deg. F.
Mid Slope Winds: Light winds. Gusts up to 25 mph in the morning. Light winds. Light winds.
Expected snowfall: 0 in. 0 in. Up to 1 inch. | SWE = less than 0.10 inch. in.
Over 10,000 ft.
Friday Friday Night Saturday
Weather: Sunny then becoming partly cloudy. Snow levels below 7000 feet. Chance of precipitation is 0%. Partly cloudy. Snow levels below 7000 feet. Chance of precipitation is 0%. Mostly cloudy. Chance of snow in the afternoon. Snow levels below 7000 feet. Chance of precipitation is 35%.
Temperatures: 17 to 26. deg. F. 5 to 10. deg. F. 19 to 28. deg. F.
Ridge Top Winds: Northwest around 15 mph with gusts to 30 mph. West around 15 mph in the evening becoming light. Southwest around 15 mph in the morning becoming light.
Expected snowfall: 0 in. 0 in. Up to 1 inch. | SWE = less than 0.10 inch. 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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