Eastern Sierra Avalanche Advisory - 2/15/17

THIS AVALANCHE ADVISORY EXPIRED ON February 17, 2017 @ 5:14 pm
Avalanche Advisory published on February 15, 2017 @ 5:14 pm

Issued by Doug Lewis - Eastern Sierra Avalanche Center

Bottom Line

How to read the advisory

The primary avalanche concern for Wednesday thru Thursday will be increasing wind slabs at middle and upper elevations as pre-frontal winds increase Thursday. Wednesday, ahead of the next system warm temperatures will maintain the threat of loose wet avalanches on solar aspects at middle and lower elevations. Wednesday: Above about 9000 feet, natural avalanches are unlikely, but human triggered avalanches possible. Evaluate snow and terrain carefully and identify windloaded features such as below ridgelines and along the sidewalls of gullies. Thursday: natural avalanches possible; human- triggered avalanches likely on wind loaded slopes.

Wednesday: Below ~ 8000 feet, overall both natural unlikely and human triggered avalanches will be unlikely. Thursday, isolated pockets of Wind Slab may form in favored locations (gullies, shallow depressions, rock outcroppings, etc.) if the snowline falls further than forecasted.

No Rating

Above Treeline

No Rating

Near Treeline

No Rating

Below Treeline

Avalanche Problem 1: Wind Slab

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Moderate Southwesterly winds accompanying the arrival of the next system Thursday will form wind slabs NW-N-NE-E-SE. Heightened avalanche conditions exist on NW-N-NE-E-SE wind loaded terrain at upper and middle elevations. Be wary of hollow, drum-like sounding snow or cracks shooting out from your feet.

advisory discussion

The precipitation from last week’s Atmospheric River with reports of extensive natural avalanches. Strong Southwesterly winds formed Wind Slabs on all aspects. As the system departed, the Southwest flow veered to the Northeast As the system departed, forming additional Wind Slabs primarily on NW-W-SW-S-SE aspects. Winds decreased through the early part of the week allowing the recently formed Wind Slabs to slowly stabilize. Winds are forecasted in increase Thursday with dense snowfall, which will begin a new round of Wind Slab instability throughout the the mid to upper elevations.

Warming temperatures over the past few days helped to settle and strengthen the snowpack as a whole but southerly aspects began to shed some of the recent new snows with widespread Loose Wet avalanches, primarily below ~ 11,000’. The next system may well bring additional rain to the Lower elevations saturating the recent snowfall, which will increase the potential for Loose Wet releases. Be on the lookout for moist surface snow, pinwheels rolling down around you, and steep rocky terrain.

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Unexpected High winds - Mammoth area (2/15/17)

Bishop Creek (2/15/17) –

Solitude Canyon (2/13/17) –

Weather and CURRENT CONDITIONS

weather summary

...HIGH WIND WATCH IN EFFECT FROM LATE TONIGHT THROUGH THURSDAY AFTERNOON...

Dry conditions with increasing clouds ahead of the next system. Thursday will feature a windy day with mountain snow and lower valley rain. Friday into Saturday brings another system with less wind but additional rain and higher elevation snow. There will be a brief break before a much stronger storm brings wind and more significant precipitation early next week.

Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS

For 8,000 ft. to 10,000 ft.

	Wednesday	Wednesday Night	Thursday
Weather:	Sunny then becoming mostly cloudy.	Mostly cloudy.	Cloudy with snow.
Temperatures:	42 to 48 deg. F.	29 to 34 deg. F.	31 to 37 deg. F.
Mid Slope Winds:	Light winds becoming southwest	Southwest	Southwest
Expected snowfall:	0 in.	0 in.	up to 6 in.

Over 10,000 ft.

	Wednesday	Wednesday Night	Thursday
Weather:	Sunny then becoming mostly cloudy.	Mostly cloudy.	Cloudy with snow.
Temperatures:	36 to 42 deg. F.	25 to 30 deg. F.	26 to 32 deg. F.
Ridge Top Winds:	Light winds becoming southwest	Southwest	Southwest
Expected snowfall:	0 in.	0 in.	2 to 6 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.