Avalanche Advisory: Sunday - Feb 17, 2019

THIS AVALANCHE ADVISORY EXPIRED ON February 18, 2019 @ 6:38 am
Avalanche Advisory published on February 17, 2019 @ 6:38 am
Issued by Chris Engelhardt - Eastern Sierra Avalanche Center

The avalanche danger is CONSIDERABLE at all elevations today. WIND SLAB on Easterly thru Northerly aspects will be the major concern due to moderate (ideal snow transporting) winds and continued light snowfall. Storm slab and dry loose avalanche problems at all elevations will also be a hazard. Cautious and Conservative route finding is essential in the mountains today.

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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Moderate Westerly and Southerly winds will build wind slab on EASTERLY and NORTHERLY aspects at all elevations today.  These more moderate velocities (15-25mph) expected for today are perfect for loading leeward aspects with freshly deposited snow. In addition to today’s conditions, southerly winds from the previous day’s storm have been extreme with velocities of over a 100mph which can produce widespread and unpredictable loading patterns on all aspects and elevation bands. Expect wind slab development on nearly every aspect in the mountains today!   It is also important to point out that a RAIN CRUST was created up to around 10000ft in the forecast area during Feb 14/15. Although new snow has been shown to be bonding fairly well to this layer, it is now buried up to 3ft down and could provide a good sliding surface for new loading slabs. Performing your own local snow assessments for this rain crust is advised. Avoid skiing over terrain traps such as depressions and gully features and be observant for new cornice growth, cross-loading adjacent to ridgelines and micro-terrain features, and avoid convex rolls and unsupported slopes.

Avalanche Problem 2: Storm Slab
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Violent winds up high will have reduced storm slab issues at upper elevations, but mid to lower elevations could have storm slab development on a wide range of aspects today. Be vigilant and observant for signs of instability today such as audible whumphing of the snow, shooting cracks and recent avalanche activity. Upwards of another 80-90” of snow has fallen through the preceding storm cycle creating a significant amount of snow bonding, settling and in some cases gaining tension in areas such as convex rolls where a trigger may start fresh slabs in motion.

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 trigger 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

Quite the February we’ve been having with reports coming that this month is potentially one of the biggest on record.  With such stormy and violent conditions of late, extreme winds, a rain event, and lack of observations above tree line; it will be good to ease into terrain with a careful eye and good communication with your partners in the upcoming lull in weather. Appears we may have a few days of calmer conditions before a potential slider works its way into the forecast area mid-week. Enjoy and be safe out there!!! Due your own local assessments and follow foundational protocols for backcountry travel.

Weather and CURRENT CONDITIONS
weather summary

Cloudy skies will persist with flurries and pulses of snow through this morning and afternoon. Light (1-3”) accumulations of snow are expected today with a gradual tapering off thru the afternoon. Winds are also on the decrease, but will prevail from the West with more moderate speeds. Below normal temperatures will continue (15-23F @ 8-10000ft & 8-13F above 10000ft) making for chilly conditions today, so be sure to be prepared, especially for the wind chill in more exposed areas.

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 likely in the morning, then snow showers in the afternoon. Cloudy. Snow showers likely in the evening, then slight chance of snow showers after midnight. Mostly cloudy. Slight chance of snow showers through the day.
Temperatures: 15 to 23. deg. F. 1 to 7 deg. F. 15 to 23 deg. F.
Mid Slope Winds: West around 15 mph with gusts to 25 mph. North around 15 mph 15 to 23.
Expected snowfall: 80% probability of 1 to 4 inches. 20% probability of 4 to 7 inches. in. 70% probability up to 2 inches. 30% probability no accumulation. in. No accumulation in.
Over 10,000 ft.
Sunday Sunday Night Monday
Weather: Cloudy. Snow likely in the morning, then snow showers in the afternoon. Cloudy. Snow showers likely in the evening, then slight chance of snow showers after midnight. Mostly cloudy. Slight chance of snow showers through the day.
Temperatures: 8 to 13 deg. F. 4 below to 1 above zero. deg. F. 8 to 13 deg. F.
Ridge Top Winds: West 15 to 25 mph with gusts to 35 mph North 15 to 25 mph with gusts to 40 mph. North 15 to 25 mph with gusts to 35 mph
Expected snowfall: 70% probability of 2 to 4 inches. 30% probability of 4 to 7 inches. in. 70% probability up to 1 to 3 inches. 30% probability no accumulation. 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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