Avalanche Advisory: Saturday - Mar 14, 2020

THIS AVALANCHE ADVISORY EXPIRED ON March 15, 2020 @ 6:53 am
Avalanche Advisory published on March 14, 2020 @ 6:53 am
Issued by Chris Engelhardt - Eastern Sierra Avalanche Center

CONSIDERABLE avalanche danger exists Above and Near tree line Saturday for WIND SLAB on NW-N-E-SE ASPECTS. MODERATE avalanche danger will develop below tree line. Extreme SW winds will actively be cross loading and forming fresh wind slab on terrain conducive to capturing snow, such as couloirs, and slopes adjacent to ridgeline, cliff bands and rock outcroppings. Although likely small in size, natural avalanches are certainly possible and human triggered avalanches are likely today. Conservative decision making and route selection is key.

3. Considerable

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Above Treeline
Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.

3. Considerable

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Near Treeline
Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.

2. Moderate

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Below Treeline
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
    Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.
Avalanche Problem 1: Wind Slab
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    Certain
    Very Likely
    Likely
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    Very Large
    Large
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W-SW winds ramped up Friday with extreme velocities (upwards of 100mph) at ridge top during the night and continuing today. NORTHERLY-EASTERLY ASPECTS at ALL ELEVATIONS will potentially be harboring  fresh WIND SLAB Saturday. Be on the lookout for unstable wind slab on a variety of terrain features such as slopes adjacent to rock outcropping, cliff bands and side walls of gullies and chutes. Fresh snowfall that has started Saturday morning combined with residing loose snow from this past week’s storms will be redistributed forming wind slab throughout the range. Field observations this week have reported 15-20cm of new snow in the southern part of the range (SF Big Pine & Kearsage Area) as well as plenty of soft surface snow readily available for wind transport in the Mammoth Crest area. Forecasters observed significant snow transport Friday from strong high elevation W-SW winds.

Be observant of blowing snow, recent loose snow avalanche activity, and fresh cross loaded ribbons and pillows of snow established adjacent to terrain features. Shooting cracks 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. Recent natural avalanche activity and debris are sure signs of unstable conditions.

Weather and CURRENT CONDITIONS
weather summary

Violent SW winds and cloudy skies will dominate Saturday with snowfall in the mountains. Temperatures will still climb into the low 40sF for lower mountain elevations and should remain below freezing (21-31F) above 10000ft. Extreme SW winds will average 40-60mph with gusts up to 90mph at ridge top. The brunt of the storm in relation to snow looks to impact our area Saturday night into Sunday, but expect potentially 3-6” to fall in the higher elevations Saturday, with 1-3” for the lower mountain elevations. Snowfall is forecast to continue tonight with additional accumulations into Sunday with accumulations in the 7-14” range.

Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 8,000 ft. to 10,000 ft.
Saturday Saturday Night Sunday
Weather: Partly cloudy. Chance of snow through the day. Snow levels below 7000 feet. Chance of precipitation is 40%. Mostly cloudy. Snow likely in the evening, then snow after midnight. Snow levels below 7000 feet. Chance of precipitation is 65%. Mostly cloudy. Snow likely. Snow levels below 7000 feet. Chance of precipitation is 65%.
Temperatures: 32 to 42. deg. F. 21 to 27. deg. F. 27 to 37. deg. F.
Mid Slope Winds: Southwest 20 to 35 mph with gusts to 75 mph. Southwest 20 to 30 mph with gusts to 65 mph. Southwest 20 to 35 mph with gusts to 60 mph.
Expected snowfall: 60% probability of 1 to 3 inches. 40% probability of 3 to 6 inches. | SWE = up to 0.15 inch. in. 60% probability of 4 to 8 inches. 40% probability of 8 to 12 inches. | SWE = 0.25-0.50 inch. in. 70% probability of 2 to 6 inches. 30% probability of 6 to 12 inches. | SWE = 0.20-0.45 inch. in.
Over 10,000 ft.
Saturday Saturday Night Sunday
Weather: Partly cloudy then becoming mostly cloudy. Chance of snow. Snow levels below 7000 feet. Chance of precipitation is 50%. Mostly cloudy. Snow. Snow levels below 7000 feet. Chance of precipitation is 80%. Mostly cloudy. Snow likely in the morning, then snow in the afternoon. Snow levels below 7000 feet. Chance of precipitation is 70%.
Temperatures: 21 to 31. deg. F. 14 to 19. deg. F. 18 to 26. deg. F.
Ridge Top Winds: Southwest 40 to 60 mph with gusts to 90 mph. Southwest 35 to 55 mph with gusts to 80 mph. Southwest 30 to 50 mph with gusts to 75 mph.
Expected snowfall: 40% probability of 1 to 3 inches. 60% probability of 3 to 6 inches. | SWE = up to 0.15 inch. in. 70% probability of 4 to 8 inches. 30% probability of 8 to 12 inches. | SWE = 0.30-0.55 inch. in. 70% probability of 3 to 6 inches. 30% probability of 6 to 12 inches. | SWE = 0.25-0.50 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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