Avalanche Advisory: Tuesday - Jan 28, 2020

THIS AVALANCHE ADVISORY EXPIRED ON January 29, 2020 @ 6:40 am
Avalanche Advisory published on January 28, 2020 @ 6:40 am
Issued by Chris Engelhardt - Eastern Sierra Avalanche Center

LOW avalanche danger exists at all Elevations. Monitor for isolated pockets of Wind Slab on Northerly-Easterly aspects and be aware of potential Loose Wet activity on Southerly aspects. Watch for unstable snow in isolated areas or extreme terrain and maintain fundamental backcountry travel protocols.

1. Low

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

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.
    Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
Avalanche Problem 1: Wind Slab
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Be aware of fresh wind slab and new snow deposits after Sunday’s light snow accumulations (1-4”). SW-Westerly winds were actively transporting snow throughout the day Sunday. Northerly-Easterly aspects at Upper to Middle elevations will be of most concern. Look out for unstable snow conditions such as fat pillows adjacent to ridgelines, rock outcroppings or cliff bands, and avoid riding over terrain traps.

Avalanche Problem 2: Loose Wet
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Sunny skies and warm temperatures could contribute to small loose wet activity on sunny aspects today. Shedding snow may present hazard in exposed or extreme terrain with warming contributing to loosening of new snow deposits. If travelling beneath aspects being warmed by the sun, be aware of overhead hazards, especially if you’re in terrain that could funnel or direct small amounts of shedding snow towards you (e.g. couloirs that have South facing aspects above that shed their snow into your climbing or skiing objective).

Avalanche Problem 3: Persistent Slab
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Large collapses, surface cracking, and propagating test results have been observed throughout the range within our relative thin and degrading snowpack. A majority of these signs of poor stability are attributed to loose faceted snow residing under buried crusts or old wind board layers within the upper part of the snowpack. There have been no avalanches reported on these buried weak layers, but it is a present and real condition that should be considered in making wise terrain choices. Distribution is inconsistent and isolated to slopes with poor snowpack structure and areas where there is contiguous slab. Cross loaded gullies within thin vegetated areas, for example, have been zones where this condition has been found. Persistent slabs can be much more unpredictable than new snow storm or wind slabs and can be triggered from a distance and propagate over further distances in unpredictable patterns.

advisory discussion

On Sunday, 1-4” of snow fell across the forecast area with W-SW winds transporting it to a variety of leeward terrain conducive to capturing snow. Observations in the Mammoth area yesterday recorded thin, low volume wind slab in steep N-E aspects adjacent to rock features and sidewalls of gullies. There were also small cross loaded pillows on southerly aspects that were a bit reactive, but also were cooked down by yesterday’s sun and warmth. Although reactive, this shallow new wind slab was not running far, nor entraining much snow as it slid minimal distances. Monday’s warm temperatures and sunny skies also contributed to cooking the sunny aspects and reducing the amount of available snow for transport by todays predicted west-southwest flow. Sunny skies and warming today could loosen small deposits of Sunday’s snow on warming aspects, particularly S-W. Shedding snow could entrain enough to make for an unpleasant impact, especially in extreme or exposed terrain.

 

recent observations
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1/27 – Mammoth Area –TJ Bowl –thin and small wind slabs

1/27 – Mammoth Area –Lakes Basin –warm temps, isolated small wind slab

1/26 – Bishop Area – Basin Mountain –spatial variability & new snow

1/25 – McGee Creek – Baldwin Cirque – Snow Conditions

1/24 – McGee Creek Area –McGee Mountain – Collapse/shooting cracks

Weather and CURRENT CONDITIONS
weather summary

Another mild day is on tap as we near the end of January. Partly cloudy skies will give way to sunny weather with warm temperatures and light to moderate West- Southwesterly winds Tuesday. Ridge top winds could gust up to 55mph, but will average 25-40mph. Temperatures will again climb into the low 40sF in the lower mountains and reach 24-30F above 10000ft. Record high temperatures are predicted for this weekend.

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: Mostly cloudy then becoming partly cloudy. Snow levels below 7000 feet. Chance of precipitation is 0%. Clear. Snow levels below 7000 feet. Chance of precipitation is 0%. Sunny. Snow levels below 7000 feet. Chance of precipitation is 0%.
Temperatures: 32 to 42. deg. F. 16 to 21. deg. F. 29 to 37. deg. F.
Mid Slope Winds: Southwest to west 10 to 20 mph with gusts to 40 mph. West to northwest 15 to 25 mph with gusts to 40 mph in the evening decreasing to 10 to 20 mph. North to northeast 15 to 25 mph with gusts to 50 mph.
Expected snowfall: 0 in. 0 in. 0 in.
Over 10,000 ft.
Tuesday Tuesday Night Wednesday
Weather: Mostly cloudy then becoming sunny. Snow levels below 7000 feet. Chance of precipitation is 5%. Clear. Snow levels below 7000 feet. Chance of precipitation is 0%. Sunny. Snow levels below 7000 feet. Chance of precipitation is 0%.
Temperatures: 24 to 30. deg. F. 12 to 18. deg. F. 22 to 30. deg. F.
Ridge Top Winds: Southwest to west 25 to 40 mph with gusts up to 55 mph. West to northwest 25 to 35 mph with gusts to 50 mph in the evening decreasing to 15 to 25 mph with gusts to 40 mph. North 30 to 50 mph with gusts to 75 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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