Avalanche Advisory: Thursday - Jan 10, 2019

THIS AVALANCHE ADVISORY EXPIRED ON January 11, 2019 @ 6:43 am
Avalanche Advisory published on January 10, 2019 @ 6:43 am
Issued by Steve Mace - ESAC

Considerable avalanche danger will remain today at upper elevations on W-NW-N-NE-E aspects.  8-10”of snow fell yesterday accompanied by moderate to strong winds.  Expect to find sensitive wind slabs on northerly aspects in areas where topography encourages drifting. 

Expect to see significant warming today as we enter into a period of high pressure. Loose wet avalanches will be possible on solar aspects today at all elevations as day time temperatures rise and the skies clear.

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.

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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The primary concern today will be fresh wind slabs sensitive to human trigger on northerly aspects at mid and upper elevations.  8-10” of dense snow fell yesterday with moderate to strong winds and significant transport noted near and above tree line. Use surface clues to identify and avoid wind-loaded slopes over 35°. Fresh cornice growth, drifting, and uneven snow surfaces are all signs that wind slabs are in near by terrain.  Use extra caution if heading into the alpine today where the size and distribution of wind slab is likely greater. As temperatures rise today, there is a possibility that the sensitivity of wind slabs on more solar aspects may increase. 

While unlikely there is still a possibility of finding lingering wind slabs in more sheltered areas at lower elevations.  New snow will make surface clues very difficult if not impossible to find, when in doubt stick to less consequential lower angle terrain. 

Avalanche Problem 2: Loose Wet
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The weather will change significantly today as we see clearing skies, a rise in temperature, and a drop in wind speed.  Loose wet avalanches will be possible on solar aspects today at all elevations. Be on the look out for signs of warming including wet snow surface and rollerball activity. While resulting slides are likely to be small they could easily cause a fall or carry a person through unpleasant terrain.

 

Avalanche Problem 3: Persistent Slab
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Structure in the snow pack remains poor and weak faceted snow continues to be found 60-80cm from the surface.  Test results have been mixed and while we have not had reports of avalanche activity on these deeper weak layers the possibility of triggering one remains.  Persistent slab avalanches are dangerous and unpredictable, propagating long distances and running further down slope.  Careful snow pack evaluation and conservative terrain choices that limit your exposure are recommended.

advisory discussion

As we move into a period of favorable weather it is important to remain vigilant.  We have a wide range of avalanche problems today affecting all aspects and elevations, travel is unpleasant and difficult in many areas, and the snowpack structure remains poor.  

While persistent slabs are proving unlikely, avalanches breaking on these deeper weak layers would be large and destructive.  In addition, forecaster confidence in the distribution and reactivity of this weak layer is low and continued caution is recommended.   

Weather and CURRENT CONDITIONS
weather summary

Expect to see sunny skies and warm temperatures today as a high-pressure system moves into the area. Daytime highs will be in the mid 30’s today at upper elevations and ridge top winds will be light to moderate out of the south with gusts expected to reach 35mph.  

Tomorrow looks to be very similar with a slight increase in our winds expected in the afternoon. 

Another storm system is expected to move in later this weekend or early next week as the high-pressure system exits the area and makes its way to the east.  

Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 8,000 ft. to 10,000 ft.
Thursday Thursday Night Friday
Weather: Sunny. Clear. Sunny. Then becoming Partly cloudy
Temperatures: 36 to 41. deg. F. 18 to 23. deg. F. 35 to 41. deg. F.
Mid Slope Winds: Light winds. Light winds becoming south 10 to 15 mph after midnight. South 10 to 15 mph with gusts to 30 mph.
Expected snowfall: None in. None in. None in.
Over 10,000 ft.
Thursday Thursday Night Friday
Weather: Sunny. Clear. Partly cloudy then becoming mostly cloudy.
Temperatures: 30 to 35. deg. F. 14 to 19. deg. F. 28 to 34. deg. F.
Ridge Top Winds: Southwest 10 to 20 mph. Gusts up to 35 mph in the morning. Southwest 10 to 15 mph. Gusts up to 25 mph after midnight. South 15 to 25 mph. Gusts up to 25 mph increasing to 35 mph in the afternoon.
Expected snowfall: None in. None in. None 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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