Avalanche Advisory: Friday - Mar 29, 2019

THIS AVALANCHE ADVISORY EXPIRED ON March 30, 2019 @ 6:36 am
Avalanche Advisory published on March 29, 2019 @ 6:36 am
Issued by Steve Mace - ESAC

The avalanche danger remains CONSIDERABLE at mid and upper elevations and MODERATE at lower elevations.  Fresh, sensitive wind slabs remain the primary concern today on Northerly and Easterly aspects at middle and upper elevations, however, with warming temperatures, light winds, and clear skies, Loose wet avalanches will also be possible on solar aspects.  Conservative terrain selection and careful snowpack evaluation will be crucial 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.

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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8-18” of new snow fell in the northern reaches of the forecast area during the last couple of days accompanied by strong SW winds.  Steady moderate SW winds continued to load leeward slopes throughout the day yesterday.  As wind speeds drop today, the likelihood of fresh slab development will diminish, but wind slabs deposited during and after the storm will still be sensitive to human trigger.  Problem areas will primarily be on northerly and easterly aspects at mid and upper elevations where terrain features encourage drifting. The leeward sides of ridgelines, gully features, and cross-loaded depressions are all suspect.  Be particularly cautious in extreme terrain or on steep unsupported slopes.  Surface clues such as blowing snow, recent cornice growth and uneven snow surfaces can help to identify and avoid areas of recent wind deposit. 

Avalanche Problem 2: Loose Wet
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With warm temperatures, light winds, and clear skies today it will be possible to see some loose wet activity on solar aspects. While the biggest risk will be at lower elevations the intense March sun will be out in force today and it may be possible to see significant surface warming even at higher elevations. Be on the look out for wet, sticky snow surface, and rollerballs as these are signs of surface warming and may foreshadow larger point release avalanches.

Avalanche Problem 3: Storm Slab
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While the sensitivity of Storm slab avalanches has likely decreased today it will not be impossible to find residual storm instabilities, particularly in sheltered and shaded terrain. Wumphing, shooting cracks and recent avalanches are all signs of nearby hazard.  Heightened caution is advised in steep terrain particularly in areas where terrain features increase the consequence of an avalanche.  Even relatively small loose sloughs can knock you off your feet and potentially carry you through some unpleasant terrain.

advisory discussion

Before our most recent storm surface conditions were a mixed bag of wind board, melt freeze crusts and loose-grained faceted snow.  While the new and old snow seems to be bonding well at lower elevations, this is less pronounced at upper elevations.  These sometimes-slick interfaces can increase the sensitivity of slab avalanches. Avalanches today may propagate wider, and run further than you may normally expect.

A number of reports of natural and skier-triggered avalanches came in yesterday including some very close calls in extreme, alpine terrain.  These act as good reminders that even relatively small spring storms can bring a variety of avalanche concerns. As spring approaches the long days and mild weather have a tendency to draw us into more consequential terrain. But its important to give the snow pack time to adjust.  Keep track of changes in the snow surface, remember that wind slabs remain a concern for many days even after the wind has slowed or even stopped all together, and always use safe travel protocols.  

Weather and CURRENT CONDITIONS
weather summary

 Sunny skies, light winds, and warm temperatures should make for a pleasant day on the east side.   Expect highs in the mid 30's at upper elevations with ridge top winds expected only into the teens today.  At lower elevations, the temperature will reach into the 40’s.  There is a chance we will see some partly cloudy skies this afternoon with a slight chance of isolated showers.

Temperatures are expected in the low teen this evening with clearing skies and diminishing winds. Tomorrow promises to be clear calm and warm as a brief stint of high pressure takes hold.  This quiet weather may be short-lived however as another system is expected to impact the area after the weekend.

Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 8,000 ft. to 10,000 ft.
Friday Friday Night Saturday
Weather: Sunny. Partly cloudy then becoming clear. Sunny.
Temperatures: 32 to 42. deg. F. 14 to 19. deg. F. 33 to 41. deg. F.
Mid Slope Winds: Southwest 5 to 10 mph. West around 10 mph in the evening becoming light. Light winds.
Expected snowfall: 0 in. 0 in. 0 in.
Over 10,000 ft.
Friday Friday Night Saturday
Weather: Sunny then becoming partly cloudy. Partly cloudy then becoming clear. Sunny.
Temperatures: 23 to 31. deg. F. 8 to 13. deg. F. 26 to 32. deg. F.
Ridge Top Winds: Southwest 5 to 10 mph. West around 10 mph becoming light. Light winds.
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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