Avalanche Advisory: Monday - Feb 19, 2018

THIS AVALANCHE ADVISORY EXPIRED ON February 20, 2018 @ 6:35 am
Avalanche Advisory published on February 19, 2018 @ 6:35 am
Issued by Josh Feinberg - Eastern Sierra Avalanche Center

As new snow accumulates from last night through today, accompanied by strong to moderate winds, avalanche danger will increased to CONSIDERABLE for areas that receive up to 6” of total new snow due to fresh wind slabs at mid to upper elevations on all aspects.  Avoid steep slopes with fresh dense wind deposits. 

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.

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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    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

Light snow showers began last night and will continue thru the day, with up to 6” of total new snow possible for some areas.  Strong winds out of the SW will gradually decrease to moderate levels and shift out of the NW for most of today gusting in the 40s at most elevations.  This combination will certainly build new sensitive wind-slabs at mid to upper elevations below ridgelines, in the sidewalls of gullies, across slopes and around other features that promote drifting.  All aspects are suspect due to the shift in winds, but as the day progresses NE to E thru S to SW slopes will be of greatest concern as winds settle in out of the NW.  Human triggering will be likely, and natural avalanches possible in areas with the greatest amounts of new snow.  Avoid fresh dense wind deposits on steep slopes, and look for clues like cracks shooting from your skis indicating sensitive unstable snow.

advisory discussion

Very strong SW winds gusting over 100mph at ridge-tops persisted through most of yesterday and last night as a cold front made its way into our area.  Despite limited loose snow available for transport, snow could still be seen getting blown across ridges at tree line and above throughout most of the range.  The very high winds likely resulted in most of this snow sublimating into the atmosphere, but some likely got deposited into small sensitive wind slabs.  As new snow began falling last night and is forecasted to continue through most of today, and winds decrease to more moderate levels more ideal for wind slab deposition, fresh sensitive wind slabs will become more and more widespread throughout the day.  Firm surface conditions previous to this new snow, from hard wind-board to melt/freeze crusts, are very widespread.  These firm surfaces will be easy for new wind slabs to fail on, as well as riders to fall out of control on.  Beware of all the dangerous obstacles in our shallow snowpack as well.  The relatively small amount of new snow expected (possibly up to 6" in some areas) just isn't enough to raise concern over storm slabs in sheltered areas.  

recent observations
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-2/18: Bishop to Mammoth - Turbulent snow transport

-2/17: June - Negatives - increasing winds, snow stability

-2/16: Mammoth - Red Cone/Hollywood Trees/McLoad Lake - Stability & Persistent Weakness Assessment

-2/16: VA Lakes - Wind Effected

Weather and CURRENT CONDITIONS
weather summary

A large-scale trough of low pressure settles into our region today, bringing unsettled very cold air (coldest of the season!), snow showers, and wind.  Up to 6” total new snow could be possible for some areas by evening time.  Temperatures will barely reach double digits around 10,000’ and strong winds will decrease through the day and shift from out of the SW to the NW with gusts in the 40s at most elevations. 

The rest of the week will remain very cold, with a slight warming on Wednesday before another cold front pushes thru on Thursday bringing more unsettled weather and light snow showers.

Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 8,000 ft. to 10,000 ft.
Monday Monday Night Tuesday
Weather: Mostly cloudy. Snow showers likely. Mostly cloudy then becoming partly cloudy. Chance of snow showers through the night. Sunny
Temperatures: 11 to 19 deg. F. -2 to 4 deg. F. 18 to 24 deg. F.
Mid Slope Winds: Northwest North Northwest
Expected snowfall: 1 to 4 in. up to 1 in. 0 in.
Over 10,000 ft.
Monday Monday Night Tuesday
Weather: Mostly cloudy. Snow showers likely. Mostly cloudy then becoming clear. Snow showers likely in the evening. Sunny
Temperatures: 5 to 10 deg. F. -7 to -2 deg. F. 13 to 18 deg. F.
Ridge Top Winds: Northwest Northwest Northwest
Expected snowfall: 1 to 4 in. up to 1 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 Snowpack Summary is provided by the Eastern Sierra Avalanche Center, who is solely responsible for its content.

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