Avalanche Advisory: Saturday - Jan 19, 2019

THIS AVALANCHE ADVISORY EXPIRED ON January 20, 2019 @ 6:54 am
Avalanche Advisory published on January 19, 2019 @ 6:54 am
Issued by Steve Mace - ESAC

Avalanche Danger will be CONSIDERABLE at all elevations today. Human triggered avalanches remain likely. Sensitive wind slab, storm slab, and persistent slab avalanches are the main concern, however loose wet avalanches will also be possible today on solar aspects.  Cautious route finding and conservative decision making will be essential today as you travel into the backcountry.  

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.

3. Considerable

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Below Treeline
Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.
    Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.
Avalanche Problem 1: Wind Slab
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Size, sensitivity, and distribution of wind slabs will vary a lot today.   With moderate west winds yesterday expect to find small, fresh wind slabs on easterly terrain at mid and upper elevations. These fresh wind slabs are likely to be sensitive to human trigger.   It will also be possible to find large stubborn wind slabs on more northerly terrain, results of last weeks storm which brought 3-5 ft of new snow accompanied by strong to extreme southwest winds. Keep in mind that these extreme winds distributed snow in unpredictable ways. It will be possible to find lingering wind slab in unexpected places such as further down slopes and in more sheltered areas.  As the temperature rises today wind slabs are likely to get more sensitive especially on solar aspects.  

Avalanche Problem 2: Storm Slab
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Numerous reports of storm slab avalanches came in yesterday, including a skier triggered slide in the Sherwin's.  As the snowpack adjusts to the new load, it will be essential to keep in mind that slopes over 30° are still suspect.  The presence of buried surface hoar in many sheltered locations is particularly concerning. Avalanches releasing on this dangerous weak layer have the potential to propagate long distances and run in lower angle terrain. Forecaster confidence on the distribution of preserved buried surface hoar is low; however, it has been confirmed in at least one recent avalanche. Careful snowpack evaluation will be essential and conservative terrain selection is highly recommended. 

Avalanche Problem 3: Persistent Slab
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Persistent slab avalanches will be possible today.  Significant weight was added to the snowpack this week, stressing an already precarious structure.  Loose faceted snow continues to be found near the ground throughout the forecast area.  These persistent avalanches will be more sensitive in areas where the overall snowpack is thinner.  With the risk of wind slab and storm slab avalanches today it is important to keep in mind that even relatively small avalanches have the potential to step down to these deeper layers.  Resulting avalanches are likely to be very large and destructive, propagating long distances and traveling far into runout zones. Confidence in the sensitivity of these persistent slabs is low, and care should be taken to stay far away from suspect slopes.  

advisory discussion

In addition to the problems listed above, it's likely that we will see loose wet activity on solar aspects.  With increased solar radiation and warm temperatures today, keep an eye out for signs of warming like wet, sticky snow and roller ball activity. Resulting avalanches are likely to be small but they will have the potential to cause a fall and carry a skier.   

As you make your holiday weekend plans keep in mind that dangerous avalanche conditions exist throughout the forecast area.  We are dealing with multiple avalanche issues that range in sensitivity and distribution and have very different implications for travel.  Human triggered avalanches are likely today at all elevations, and resulting avalanches have the potential to be very large and destructive. Use careful snowpack evaluation and conservative route choice to limit your exposure. When in doubt avoid avalanche terrain.

Weather and CURRENT CONDITIONS
weather summary

Mild weather is expected today marked by partly cloudy skies, light southwest winds, and temperatures approaching 40° above 10,000'.  Things will cool off tonight as temperatures drop below freezing and the winds increase with gusts expected to reach 55mph after midnight.  

Winter is expected to return tomorrow as a cold front moves into the area.  3-5" of snow expected at upper elevations. Winds tomorrow will to increase to moderate and remain southwest while temperatures drop throughout the day. as a

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. Partly cloudy. Partly cloudy then becoming mostly cloudy. Chance of snow through the day. Snow levels below 7000 feet increasing to 7000 feet in the afternoon. Chance of precipitation is 45%.
Temperatures: 40 to 46. deg. F. 22 to 27. deg. F. 33 to 41. deg. F.
Mid Slope Winds: Southwest 10 to 15 mph with gusts to 35 mph. Southwest 10 to 15 mph. Gusts up to 40 mph increasing to 50 mph after midnight. Southwest 15 to 30 mph increasing to 30 to 40 mph in the afternoon. Gusts up to 80 mph.
Expected snowfall: None in. None in. 60% probability of 1 to 2 inches. 40% probability of 3 to 5 inches. | SWE = up to 0.15 inch. in.
Over 10,000 ft.
Saturday Saturday Night Sunday
Weather: Partly cloudy. Partly cloudy. Partly cloudy then becoming mostly cloudy. Chance of snow through the day. Snow levels below 7000 feet increasing to 7000 feet in the afternoon. Chance of precipitation is 50%.
Temperatures: 34 to 39. deg. F. 18 to 23. deg. F. 24 to 30. deg. F.
Ridge Top Winds: Southwest 15 to 25 mph with gusts to 35 mph. Southwest 20 to 35 mph. Gusts up to 40 mph increasing to 55 mph after midnight. Southwest 35 to 55 mph with gusts to 80 mph.
Expected snowfall: None in. None in. 60% probability of 1 to 2 inches. 40% probability of 3 to 5 inches. | SWE = up to 0.20 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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