Avalanche Advisory: Sunday - Feb 10, 2019

THIS AVALANCHE ADVISORY EXPIRED ON February 11, 2019 @ 6:45 am
Avalanche Advisory published on February 10, 2019 @ 6:45 am
Issued by Chris Engelhardt - Eastern Sierra Avalanche Center

The avalanche danger is HIGH at upper and middle elevations. CONSIDERABLE danger will exist for lower elevations. WIND SLAB on Northerly-Easterly aspects will be the major concern with additional storm slab and dry loose avalanche problems existing.

4. High

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Above Treeline
Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.

4. High

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Near Treeline
Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.

3. Considerable

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Below Treeline
Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.
    Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.
Avalanche Problem 1: Wind Slab
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Strong to extreme Southerly and Westerly winds will build wind slab on NORTHERLY and EASTERLY aspects particularly in the upper elevations and mid elevations today. Wind direction has been all over the place, and with velocities of over 100mph yesterday/last night, snow loading patterns will be quite dynamic and widespread. Expect wind slab development on every aspect in the mountains today! Avoid skiing over terrain traps such as depressions and gully features.

Avalanche Problem 2: Storm Slab
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The violent winds up high will have reduced storm slab issues at upper elevations, but the mid to lower elevations could have storm slab development on a wide range of aspects today. Although relatively light in nature, the significant amount of newly fallen snow the past 2 days will start to settle, bond, be pressed by winds and over time gain more cohesiveness which in some cases could lead to storm slab conditions. Be vigilant and observant for signs of instability today such as audible whumphing of the snow, shooting cracks and recent avalanche activity. Terrain features such as convex rolls, unsupported slopes above cliffs, and steep slopes above terrain traps should be avoided.

Avalanche Problem 3: Loose Dry
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Cold temperatures, strong to extreme loading winds and multiple feet of new snow will make loose dry avalanches very likely on all aspects. These avalanches triggered naturally by winds, falling tree bombs, cliff shedding, or by a skier can entrain a large amount of snow once they start moving down the slope. Point releases may trigger other residing wind and storm slab instabilities and produce significant debris piles, especially in terrain traps such as depressions and gullies.

advisory discussion

There were a lot of people out enjoying the mountains and the fresh snow conditions yesterday. The increase in winds and added snowfall accumulations will make for more hazardous avalanche and deep snow immersion conditions today. Terrain or slopes that were amazing yesterday could have changed significantly with the extreme winds overnight and additional snowfall. Do your own local assessments and follow foundational protocols for backcountry travel. Travelling in avalanche terrain today is not recommended.

SKIING WITH A PARTNER is always preferred in the backcountry, but is even now more important both at the ski areas and out of bounds. Deep snow immersion is a real hazard right now that should be discussed with your group before riding today. Falling headfirst in a tree well will be hazardous. The key thing is to ski with a partner who will be able to help you get out of deep snow if you take a fall. If you find yourself in a tree well or deep snow situation, try not to panic, maintain a good airway to breath, and slowly dig yourself out in a planned concerted effort.

Weather and CURRENT CONDITIONS
weather summary

The storm continues through today with cloudy skies, strong to extreme S-W winds (possible gusts reaching 100mph on ridgetops) and increasing snow totals. Last night, another foot of snow fell and upwards of another 6-12” is slated to fall today. Saturday/Sunday snow totals combined with the nearly 2ft of snow that fell Friday night through Saturday will present deep surface conditions. Temperatures remain chilly with single digits to teens (7-13F) in the upper elevations and 14-22F in the mid to lower elevations. Snow and winds should taper off tonight with negative temperatures and a sunny day is on tap for Monday. We will have a brief reprieve, before another bigger, wetter, and stronger system is staged to hit the Sierra late Tuesday through Wednesday with multiple feet of snow in the forecast. Looks like we’re going to have a long ski season in 2019.

 

Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 8,000 ft. to 10,000 ft.
Sunday Sunday Night Monday
Weather: Cloudy. Snow in the morning, then snow likely in the afternoon. Snow levels below 7000 feet. Chance of precipitation is 100%. Mostly cloudy then becoming partly cloudy. Slight chance of snow showers in the evening. Snow levels below 7000 feet. Chance of precipitation is 15%. Sunny. Snow levels below 7000 feet. Chance of precipitation is 5%.
Temperatures: 14 to 22. deg. F. 2 below to 6 above zero. deg. F. 22 to 30. deg. F.
Mid Slope Winds: West 15 to 30 mph. Gusts up to 70 mph decreasing to 40 mph in the afternoon. West 15 to 20 mph with gusts to 40 mph. West around 15 mph. Gusts up to 45 mph decreasing to 35 mph in the afternoon.
Expected snowfall: 80% probability of 5 to 10 inches. 20% probability of 10 to 15 inches. | SWE = 0.30-0.55 inch. in. 80% probability up to 1 inch. 20% probability no accumulation. | SWE = 0.00-0.03. in. No accumulation. | SWE = none. in.
Over 10,000 ft.
Sunday Sunday Night Monday
Weather: Cloudy. Snow in the morning, then snow likely in the afternoon. Snow levels below 7000 feet. Chance of precipitation is 100%. Mostly cloudy then becoming partly cloudy. Slight chance of snow showers in the evening. Snow levels below 7000 feet. Chance of precipitation is 20%. Partly cloudy then becoming sunny. Snow levels below 7000 feet. Chance of precipitation is 5%.
Temperatures: 7 to 13. deg. F. 6 below to zero. deg. F. 16 to 21. deg. F.
Ridge Top Winds: Southwest 45 to 65 mph with gusts to 105 mph becoming west and decreasing to 25 to 35 mph with gusts to 60 mph in the afternoon. Northwest 20 to 30 mph with gusts to 50 mph. West 25 to 35 mph with gusts to 55 mph decreasing to 15 to 30 mph with gusts to 45 mph in the afternoon.
Expected snowfall: 80% probability of 6 to 12 inches. 20% probability of 12 to 18 inches. | SWE = 0.40-0.65 inch. in. No accumulation. | SWE = trace amounts. in. No accumulation. | SWE = 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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