Avalanche Advisory: Tuesday - Feb 25, 2020

THIS AVALANCHE ADVISORY EXPIRED ON February 26, 2020 @ 6:49 am
Avalanche Advisory published on February 25, 2020 @ 6:49 am
Issued by Josh Feinberg - Eastern Sierra Avalanche Center

Southern mountains received up to 7” of new snow up high on Saturday, while areas north received a trace.  Shifting moderate winds at upper elevations will continue thru today.  MODERATE avalanche danger still lingers at upper elevations in the southern portion of the forecast zone due to recent windslabs and slope warming from the sun. LOW avalanche danger continues for Mammoth and north, with slick and variable conditions being the greatest concern.

 

2. Moderate

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

1. Low

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Near Treeline
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

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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New snowfall varied greatly on Saturday across the forecast zone, with much greater amounts of 7” to the south and trace amounts to the north. NE winds during the storm shifted out of the W on Sunday and back to the N and NE for Monday and today gusting into the 50s at ridge tops.

 

For southern areas, sensitive to stubborn wind slabs may still be found at upper elevations just below ridgelines, sidewalls of gullies, and around rocks and other cross-loaded terrain features.  Atleast one natural avalanche big enough to bury someone occurred after the storm on Sunday triggered by sun warming rocks.  Today, human triggered avalanches are still possible, and while less likely, small natural avalanches could still occur where fresh wind deposited snow is warmed by the sun and surrounding rocks. Slick underlying conditions could increase the time required for these slabs to bond, and result in them running further than expected. Evaluate local new snowfall amounts, watch for signs such as blowing snow, and carefully assess areas with deeper wind deposited denser snow.  Be especially cautious of gully or couloir features that funnel falling snow or rocks from broad expanses, especially as slopes above warm from the sun.

 
Avalanche Problem 2: Loose Wet
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For areas that received greater amounts of fresh snow to the south, sunny skies and warm temperatures today could still trigger loose wet avalanches on E-SE-S-SW-W aspects as they warm.  Watch for signs of small rollerballs originating from rock bands as early indications that larger loose-wet avalanches could be possible.  A loose-wet avalanche could also trigger a more consequential fresh wind slab.     

advisory discussion

The new snow that fell in the southern mountains on Saturday, while not incredibly substantial, was a long awaited change to the over 3.5 straight weeks of LOW avalanche danger. For Mammoth and north, the LOW streak continues.  Variable and firm conditions abound.  A fall will be hard to self arrest in many areas, and even a small avalanche could have a very bad outcome especially with all the obstacles that exist.  Ski crampons, crampons, and ice ax have become standard equipment for travel in many areas. Enjoyable turns can still be found in northerly facing protected trees which continue to harbor softer faceted snow, as well as on sunny aspects as they warm from the sun.      

 
Weather and CURRENT CONDITIONS
weather summary

A blocking rIdge of high pressure will keep things sunny and dry thru the end of the week with above average temperatures.  For today expect mostly light N to NE winds gusting up to 50mph over ridge tops, decreasing in the afternoon.  Highs are expected to reach a few degrees warmer than yesterday breaking 40°F around 10,000’, and 50°F around 8000’.      

 

A cold front is projected to impact the Pacific Northwest this weekend, bringing increased winds for us on Saturday with chances of light snow on Sunday thru Monday, and cooler temperatures next week. 

Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 8,000 ft. to 10,000 ft.
Tuesday Tuesday Night Wednesday
Weather: Sunny. Snow levels below 7000 feet increasing to 7000 feet in the afternoon. Chance of precipitation is 0%. Clear. Snow levels 7000 feet. Chance of precipitation is 0%. Sunny. Snow levels below 7000 feet increasing to 7500 feet in the afternoon. Chance of precipitation is 0%.
Temperatures: 41 to 51. deg. F. 24 to 30. deg. F. 45 to 55. deg. F.
Mid Slope Winds: Light winds. Gusts up to 40 mph decreasing to 30 mph in the afternoon. Light winds. Gusts up to 25 mph. Light winds. Gusts up to 25 mph in the morning.
Expected snowfall: 0 in. 0 in. 0 in.
Over 10,000 ft.
Tuesday Tuesday Night Wednesday
Weather: Sunny. Snow levels below 7000 feet increasing to 7000 feet in the afternoon. Chance of precipitation is 0%. Clear. Snow levels 7000 feet. Chance of precipitation is 0%. Sunny. Snow levels below 7000 feet increasing to 7500 feet in the afternoon. Chance of precipitation is 0%.
Temperatures: 32 to 40. deg. F. 19 to 24. deg. F. 35 to 43. deg. F.
Ridge Top Winds: North 15 to 30 mph. Gusts up to 50 mph decreasing to 35 mph in the afternoon. Northeast 15 to 20 mph shifting to the west after midnight. Gusts up to 30 mph. West around 15 mph with gusts to 30 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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