Avalanche Advisory: Wednesday - Feb 27, 2019

THIS AVALANCHE ADVISORY EXPIRED ON February 28, 2019 @ 6:38 am
Avalanche Advisory published on February 27, 2019 @ 6:38 am
Issued by Chris Engelhardt - Eastern Sierra Avalanche Center

The avalanche danger is CONSIDERABLE at Upper elevations today. MODERATE avalanche danger resides at mid elevations and LOW danger exists at lower elevations. Fresh snow (4-12") accumulations today/tonight combined with loading SW winds will make for increasing danger throughout the day. WIND SLAB is of most concern today.

3. Considerable

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

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.
    Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.
Avalanche Problem 1: Wind Slab
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SW WINDS have been battering the forecast area with visible bannering of snow daily. These southerly winds will continue to blow today, and combined with fresh snowfall, will produce wind slab, especially in the nooks and crannies of alpine terrain. If we see intense periods of snow fall and accumulations, avalanche danger will certainly increase in the high/mid elevations for wind slab on Northerly aspects. Conservative decision making will be essential if wanting to venture into intricate and more extreme terrain such as couloirs and leeward catchment zones. Look for CORNICES or other fat looking snow pillows and surfaces to determine if there is fresh wind loading. New snow will be falling on a variety of old snow surfaces including smooth wind board and particularly notable below the 10000ft level, our Valentine’s Day rain crust. These shiny glass patches have been glimmering and will potentially provide slick sliding surfaces for new snow and additionally nasty slopes for a rider to take a fall on. Look for the basic red flags such as recent avalanche activity and shooting cracks while travelling today, to determine if there is increasing instability of new snow.

Avalanche Problem 2: Storm Slab
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If we see the high end of snow totals today through tonight, there will be potential for fresh storm slab primarily on Northerly aspects. New snow will be falling on a variety of wind shorn surfaces that could inhibit bonding of the new snow. Fairly warm temperatures at the mid-lower elevations will promote better bonding potential for new snow, but also could make for cohesive and tensioned storm slab that could be triggered by a skier. Again, consideration should be given to all the shiny smooth rain crust surfaces out there residing below 10000ft that could provide an optimal surface for new snow to slide on.

Weather and CURRENT CONDITIONS
weather summary

Mostly cloudy skies with snow are on tap for the forecast area today. Wind…yes, SW winds will continue, although decreasing during the day with moderate speeds in the lower to mid elevations and extreme gusts over the ridge tops reaching 90mph in the morning hours. Overall speeds should abate a bit though from the recent onslaught and decrease to the 35-50mph range in the afternoon at higher elevations. Temperatures will be above freezing (31-40F) in the lower elevations while high elevations will stay within 22-27F today. Although tapering a bit, snow will continue through the night and into Thursday with anticipated modest amounts for the area. Let’s hope we see the high end of snow totals (~1ft) over the course of the next few days to repair the recent wind damage to the snowpack surface.

 

Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 8,000 ft. to 10,000 ft.
Wednesday Wednesday Night Thursday
Weather: Mostly cloudy. Snow in the morning, then chance of snow in the afternoon. Snow levels below 7000 feet increasing to 7000 feet in the afternoon. Chance of precipitation is 100%. Mostly cloudy. Chance of snow. Snow levels below 7000 feet. Chance of precipitation is 50%. Mostly cloudy. Snow in the morning, then chance of snow in the afternoon. Snow levels below 7000 feet. Chance of precipitation is 75%.
Temperatures: 31 to 41. deg. F. 24 to 29. deg. F. 31 to 39. deg. F.
Mid Slope Winds: Southwest 15 to 30 mph with gusts to 60 mph. South 15 to 30 mph with gusts to 60 mph. Southwest 15 to 30 mph with gusts to 55 mph.
Expected snowfall: 80% probability of 3 to 6 inches. 20% probability of 6 to 8 inches. | SWE = 0.25-0.50 inch. in. 70% probability of 1 to 3 inches. 30% probability of 3 to 5 inches. | SWE = up to 0.25 inch. in. 60% probability of 2 to 5 inches. 40% probability of 1 to 3 inches. | SWE = 0.15-0.25 inch. in.
Over 10,000 ft.
Wednesday Wednesday Night Thursday
Weather: Cloudy. Snow in the morning, then snow likely in the afternoon. Snow levels 7000 feet. Chance of precipitation is 100%. Mostly cloudy. Chance of snow in the evening, then snow after midnight. Snow levels 7000 feet. Chance of precipitation is 75%. Mostly cloudy. Snow in the morning, then snow likely in the afternoon. Snow levels below 7000 feet. Chance of precipitation is 85%.
Temperatures: 22 to 27. deg. F. 17 to 22. deg. F. 23 to 29. deg. F.
Ridge Top Winds: Southwest 40 to 60 mph decreasing to 35 to 50 mph in the afternoon. Gusts up to 90 mph. Southwest 30 to 50 mph with gusts to 75 mph. Southwest 30 to 50 mph with gusts to 70 mph.
Expected snowfall: 80% probability of 3 to 8 inches. 20% probability of 8 to 10 inches. | SWE = 0.30-0.55 inch. in. 70% probability of 2 to 4 inches. 30% probability of 4 to 7 inches. | SWE = up to 0.30 inch. in. 70% probability of 3 to 6 inches. 30% probability of 2 to 4 inches. | SWE = up to 0.45 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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