Avalanche Advisory: Wednesday - Jan 23, 2019

THIS AVALANCHE ADVISORY EXPIRED ON January 24, 2019 @ 6:51 am
Avalanche Advisory published on January 23, 2019 @ 6:51 am
Issued by Chris Engelhardt - Eastern Sierra Avalanche Center

The avalanche danger is MODERATE at all elevations today. Wind slab is the primary concern in the Upper Elevations. Warming temperatures may destabilize wind slabs and cause loose wet avalanches. Persistent slab avalanches remain a problem.

2. Moderate

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Above Treeline
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

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.
    Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
Avalanche Problem 1: Wind Slab
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Moderate NORTHERLY WINDS will blow today and are projected to switch a bit to the NW from the previous NE flow from yesterday and last night. Southerly aspects up high should be the primary terrain to approach with caution due to the combination of increasing temperatures (34-39F), clear sunny skies, and fresh wind transported snow from the prevailing N winds. Be aware of constrained terrain such as couloirs that could funnel destabilizing snow on warming aspects.

Avalanche Problem 2: Loose Wet
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Increased temperatures and clear sunny days could cause some loose wet activity on solar aspects today, especially at mid to lower elevations where slopes will see significant warming.

Avalanche Problem 3: Persistent Slab
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Our persistent slab problem exists throughout the forecast zone with weak faceted snow present on a majority of aspects and elevations. There are multiple concerns, with faceted snow near the ground, mid-pack persistent grains in the form of surface hoar, melt-freeze layers, and crusts. These persistent slabs (residing cohesive slab resting on top of weak persistent grains) are unpredictable and can propagate over wide distances and run through what would often be considered safe terrain. Quite often these persistent problems stabilize over time as the snowpack adjusts and settles... we just need to be patient and continue to monitor them with the onset of high pressure and above normal temperatures forecasted for the area.

In the SOUTHERN part of the forecast zone (Bishop Creek to Rock Creek), the snowpack is typically much shallower averaging from 130-160cm in depth. Up until last week’s big storm of Jan 16-17 the snowpack was quite minimal and faceted with loose cohesionless snow. After the storm it remains very spatially variable with many places harboring thin upside down snowfields that are weak in structure. In the NORTHERN part of the forecast zone (Crowley-Mammoth-Virginia Lakes) overall snowpack is generally deeper with depths averaging from 150cm to over 300cm. Buried mid pack SURFACE HOAR is a layer we will need to continue monitor (See 1/22-Mammoth Area-Tele bowl crown profile).

advisory discussion

It will be interesting to see what will transpire with our current snowpack and persistent slab issues with the onset of above normal temperatures and a period of high pressure slated for the rest of January. 

 

Weather and CURRENT CONDITIONS
weather summary

Much warmer temperatures and sunny skies are on tap for the forecast zone with lessening winds and calmer conditions. Temperatures will be well above freezing even in the Upper elevations (34-39F) and even warmer at lower elevations (39-44F). After a good storm cycle period we are transitioning into high pressure. Shortwaves are expected to move through the area from the north and could allow a slider system back into the region, but predictability of those systems are limited to a few days out.

 

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: Sunny Clear Sunny
Temperatures: 39 to 44. deg. F. 19 to 24. deg. F. 40 to 45. deg. F.
Mid Slope Winds: Light winds. Gusts up to 25 mph increasing to 40 mph in the afternoon. Light winds. Gusts up to 40 mph decreasing to 25 mph after midnight. Light winds.
Expected snowfall: 0 in. 0 in. 0 in.
Over 10,000 ft.
Wednesday Wednesday Night Thursday
Weather: Sunny Clear Sunny
Temperatures: 34 to 39. deg. F. 15 to 20. deg. F. 36 to 42. deg. F.
Ridge Top Winds: Northwest 15 to 25 mph. Gusts up to 40 mph in the afternoon. Northwest 15 to 25 mph. Gusts up to 40 mph in the evening. North 10 to 15 mph.
Expected snowfall: 0 in. 0 in. 0 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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