Eastern Sierra Avalanche Advisory

Avalanche Advisory published on April 23, 2014 @ 7:02am: Issued by Sue Burak - Inyo National Forest
This advisory is valid for 24 hours.
bottom line

The avalanche danger is mostly Low but you may find some Moderate: 1) on slopes with lingering wind slabs from yesterday's wind along the upper elevation ridges and 2) if we get significant sun warming today, the danger will rise to Moderate for wet sluffs on steep slopes that are getting wet from sun warming.

Cornices in the Tioga Pass area are large- avoid traveling beneath cornices as the day warms up.

 

The Eastern Sierra Avalanche Center is winding down for the season - Advisories will be issued this Friday and the following Friday, May 2. 

How to read the advisory


Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern. Natural avalanches unlikely; human-triggered avalanches possible. Small avalanches in specific areas; or large avalanches in isolated areas.

avalanche danger

How to read the advisory

2. Moderate

Above treeline

1. Low

Near treeline

No Rating

Below treeline

The avalanche danger is mostly Low but you may find some Moderate: 1) on slopes with lingering wind slabs from yesterday's wind along the upper elevation ridges and 2) if we get significant sun warming today, the danger will rise to Moderate for wet sluffs on steep slopes that are getting wet from sun warming.

Cornices in the Tioga Pass area are large- avoid traveling beneath cornices as the day warms up.

 

The Eastern Sierra Avalanche Center is winding down for the season - Advisories will be issued this Friday and the following Friday, May 2. 

Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern. Natural avalanches unlikely; human-triggered avalanches possible. Small avalanches in specific areas; or large avalanches in isolated areas.

weather

Warmer temperatures are forecasted for today and Thursday before a colder and wetter storm arrives Friday. The cold front that moved through yesterday cooled temperatures 15-20 degrees colder than Monday and the weekend. Short term ridging builds over the West Coast briefly, shifting the storm track to the north.

Daytime highs will reach the mid 40's today and Thursday. Overnight lows will be in the mid 20's. The Friday storm brings strong winds and an increasing possibility for up to a foot of new snow.

recent observations

There was an outbreak of wet loose avalanches last Friday in the Tioga Pass area, otherwise avalanche conditions were very quiet over the last five days. The Tioga Pass area continues to have decent overnight refreezes with spring snow conditions on most sun exposed slopes. North aspects along the ridgetops have a variety of thin wind crusts and settled dry snow. 

Wet sluffs off White Mtn. photo credit Preston Few.

 

Avalanche Problem 1
type aspect/elevation characteristics
likelihood size trend
likely
unlikely
large
small
Decreasing Danger
description

Gusty west and northwest winds accompanied  a few inches of dry new snow that fell above 10,000 ft in the Tioga Pass area yesterday. An inch of two fell at the highest elevations in the Mammoth area. Winds gusting at the top of Mammoth Mountain reached 80 mph yesterday afternoon. After a cold night, today's clear skies, light winds and 15 degrees of warming will give the snow surface quite a shock. By tomorrow, the weather roller coaster heads back down to cold temperatures and there is a good chance of 10-12 inches of new snow  by Friday night. This late season, cold winter storm will bring winter avalanche problems this weekend and could catch people off guard who are expecting spring snow conditions.  The next advisory will be posted Friday morning and will cover the expected weekend avalanche conditions.

 

Avalanche Problem 2
type aspect/elevation characteristics
likelihood size trend
likely
unlikely
large
small
Decreasing Danger
description

The mountains picked up a trace to 3 inches of snow Tuesday. Ridgetop temperatures plummeted to the mid 20's and dropped back to the teens overnight. Winds blew new snow off the ridgetops yesterday afternoon and formed fresh drifts that might be sensitive to a person. They are going to be small but perhaps enough to knock a person over. They can be avoided by sticking to sheltered or wind-scoured areas.

Avalanche Problem 3
type aspect/elevation characteristics
likelihood size trend
likely
unlikely
large
small
Decreasing Danger
description

True to the meaning of "persistent", depth hoar remains dry at the bottom of the thin snowpack in the Rock Creek area. The most recent observations are from the weekend, when supportable skiing on winter ski was reported above 11,500 ft but conditions turned ugly on gentle and steep slopes below 11,000 ft to snowline. Melt-freeze crusts are not supporting the weight of a skier making for unpredictable and unpleasant skiing conditions. The snowpack is thin and when the surface crust  collapses into depth hoar, there isn't much snow to protect you from rocks and downed trees.

advisory discussion

Gusty west and northwest winds accompanied  a few inches of dry new snow that fell above 10,000 ft in the Tioga Pass area yesterday. An inch of two fell at the highest elevations in the Mammoth area. Winds gusting at the top of Mammoth Mountain reached 80 mph yesterday afternoon. After a cold night, today's clear skies, light winds and 15 degrees of warming will give the snow surface quite a shock. By tomorrow, the weather roller coaster heads back down to cold temperatures and there is a good chance of 10-12 inches of new snow  by Friday night. This late season, cold winter storm will bring winter avalanche problems this weekeed and could catch people off guard who are expecting spring snow conditions.  The next advisory will be posted Friday morning and will cover the expected weekend winter avalanche conditions.

 


ESAC Weather Page

Weather Station Links:
June Mountain Summit
Mammoth Summit
Rock Creek
CURRENT CONDITIONS  Weather Observations Between June (10,000 ft.) and Mammoth (11,000 ft.)
0600 temperature: 22 deg. F.
Max. temperature in the last 24 hours: 29 deg. F.
Average wind direction during the last 24 hours: WSW
Average wind speed during the last 24 hours: 45 mph
Maximum wind gust in the last 24 hours: 80 mph
New snowfall in the last 24 hours: 1 inches
Total snow depth: 16 inches
Two-Day Mountain Weather Forecast  Produced in partnership with the Reno NWS
For 8,000 to 10,000 ft.
  Today Tonight Thursday
Weather: mostly sunny mostly cloudy mostly sunny
Temperatures: 48 deg. F. 33 deg. F. 45 deg. F.
Wind direction: SW SW SW
Wind speed: 5-10 5-10 10-20
Expected snowfall: 0 in. 0 in. 0 in.
For above 10,000 ft.
  Today Tonight Thursday
Weather: mostly sunny mostly cloudy mostly sunny
Temperatures: 47 deg. F. 25 deg. F. 43 deg. F.
Wind direction: SW W W
Wind speed: 10 5-15 10-20
Expected snowfall: 0 in. 0 in. 0 in.
Disclaimer

This advisory applies only to backcountry areas outside established ski area boundaries. This advisory only describes general avalanche conditions and local variations always occur. This advisory expires 24 hours after the posted time unless otherwise noted. The information in this advisory is provided by the USDA Forest Service who is solely responsible for its content.



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