Avalanche Advisory: Friday - Feb 22, 2019

THIS AVALANCHE ADVISORY EXPIRED ON February 23, 2019 @ 5:33 am
Avalanche Advisory published on February 22, 2019 @ 5:33 am
Issued by Josh Feinberg - Eastern Sierra Avalanche Center

With 6-12” of new low-density snow since Wednesday and moderate to strong winds, MODERATE avalanche danger will exist at mid and upper elevations due to WIND SLABS. LOOSE DRY sloughs will remain a concern for lower elevation steep sheltered terrain.   

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.

1. Low

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Below Treeline
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
    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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Ridge top winds have been consistently out of the north and northeast for the last 24 hours, peaking last night with gusts over 80mph. Over prior days, winds have been shifting back and forth.  Winds are now on a decline, with N to NE gusts only expected into the 20mph range over ridge tops by this afternoon.  Below ridge tops however, wind directions have been quite variable.  Wind slabs today could range from new smooth and sensitive to older etched, rough and stubborn.  While greatest concern exists for upper elevation slopes facing NW-SW-E, be wary of all aspects. These are likely to be found just below ridgelines, the sidewalls of gullies, and around mid-slope terrain fluctuations.  Do your own localized assessments, and realize that small terrain variations could be hiding a surprising sensitive wind slab. These wind slab avalanches could knock a person off their feet, lead to a nasty fall in consequential terrain and even a burial especially if a terrain trap is involved.

Avalanche Problem 2: Loose Dry
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Cold temperatures have kept old snow soft and loose in more sheltered terrain.  Nearly a foot of new low-density snow fell in some areas between Mammoth and June since Wednesday.  Loose dry sloughs are likely in steep lower elevation sheltered terrain. These could be large enough to knock someone off their feet and lead to a possible burial especially if a terrain trap is involved. Manage slough wisely, or avoid steep sheltered terrain.

advisory discussion

Rain over Valentine’s day led to firm icy crusts up to 10,000’+ in some areas, which were then covered by additional snowfall. In wind swept areas and at lower elevations where these icy crusts are at the surface or only shallowly buried, slide for life conditions exist!  In addition these crusts can make for very good sliding surfaces for slough or larger avalanches to run on.  

Continue to be aware of large dangerous cornices at ridge tops especially on easterly facing slopes! 

recent observations

-2/21 - June - Chicken Wing:  NE winds moving snow over ridgetops, rain crust exploration.  

-2/21 - Lundy Canyon: Reports of heavy wind effected snow at low to mid elevations, upper elevations not explored.

-2/19 - June - Dream Mtn(3D Chute): Person triggered and caught in avalanche, gets taken 1,400'.  Reports of other skier triggered wind slabs that same day on other slopes with southern exposure.   

 

Weather and CURRENT CONDITIONS
weather summary

Partly cloudy skies with an occasional flurry this morning will lead to sunshine in the afternoon. North winds peaked last night and have been declining since midnight, and are only expected to gust into the 20mph range over ridge tops by this afternoon.  Expect warmer but still cold temperatures, with highs near 20° around 10,000’.  More sunshine, even warmer temperatures, and light wind is on tap for the weekend, before chances of light precipitation returns for the beginning of next week.

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: Partly cloudy then becoming sunny. Scattered snow showers in the morning. Chance of precipitation is 30%. Clear. Partly cloudy.
Temperatures: 22 to 28. deg. F. 4 to 10. deg. F. 28 to 34. deg. F.
Mid Slope Winds: North around 15 mph with gusts to 30 mph in the morning becoming light. Light winds. West around 15 mph in the morning becoming light.
Expected snowfall: No accumulation. | SWE = trace amounts. in. 0 in. 0 in.
Over 10,000 ft.
Friday Friday Night Saturday
Weather: Partly cloudy then becoming sunny. Scattered snow showers in the morning. Chance of precipitation is 30%. Clear. Partly cloudy.
Temperatures: 14 to 19. deg. F. 3 to 8. deg. F. 21 to 26. deg. F.
Ridge Top Winds: North 15 to 20 mph. Gusts up to 35 mph decreasing to 25 mph in the afternoon. Northwest around 15 mph with gusts to 25 mph. West around 15 mph with gusts to 25 mph.
Expected snowfall: 10% probability up to 1 inch. 90% probability no accumulation. | SWE = trace amounts. 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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