Mon, March 30, 2015 Turnagain Pass Avalanche Forecast

Mon, March 30th, 2015

Alpine
Above 2,500'

Moderate (2)

Treeline
1,000'-2,500'

Moderate (2)

Below Treeline
Below 1,000'

No Rating (0)

Alpine Above 2,500'		Moderate (2)
Treeline 1,000'-2,500'		Moderate (2)
Below Treeline Below 1,000'		No Rating (0)

Danger Scale:

No Rating (0)

Low (1)

Moderate (2)

Considerable (3)

High (4)

Extreme (5)

Avalanche Problem 1

Storm Slabs

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

More info at Avalanche.org

Snowfall amounts over the past several days have varied across the forecast zone. The result is slabs ranging anywhere from 6-18” in the Alpine. On East, South and West aspects these slabs sit on a thin crust. Yesterday my partner and I found these slabs to be well bonded to these crusts. Traveling along areas that were being actively loaded by wind showed no signs of instability (collapsing or cracking). Despite these encouraging results, there has been enough loading (close to 1” H20 in the Girdwood Valley) to create instability today. It will be important to be on the lookout for upside down slabs in the Alpine. Most suspect will be steep slopes receiving direct sunlight.

New snow in the Alpine is generally well bonded to underlying surfaces. Caution is still advised in terrain approaching 40 degrees as new slabs need some time to adjust. photo:Wagner

Rocky Knob Sunburst

Avalanche Problem 2

Wet Loose

Wet Loose

Wet Loose avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.

More info at Avalanche.org

While we should see mostly cloudy skies today, the sun could make an occasional appearance. If and when this happens, expect wet loose avalanches to quickly occur on terrain 40 degrees and over. Volume will be low to medium. Consequences will increase in line with the terrain. Sustained steep slopes will produce more dangerous, higher volume wet loose avalanches. If the sun pops out or the snow at your feet is wet and heavy (likely in the Treeline elevations) it will be time to back off of steep terrain.

Additional Concern

Cornice

Cornice

Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.

More info at Avalanche.org

Large unsupported masses of snow are looming over many starting zones in the Alpine. Practice good habits around cornices. On the way up pick routes that minimize time spent in the line of fire. On ridges and above starting zones keep your distance from the edge until you can see the base of the cornice and where it connects to the underlying terrain.

Weather

Mon, March 30th, 2015

Southerly flow caused by a large complex Low pressure system in the Gulf has continued to dominate the weather pattern over the last several days. This has resulted in mild temps with showery precipitation and moderate winds. The Girdwood Valley picked up 6 € of dense snow (.9 € H20) and the Turnagain Pass SNOTEL picked up 2 €/.2 (snow/H20). Higher amounts fell on the North end of Turnagain Pass.

Today that Southerly flow will continue to bring light amounts of snow and rain with only 1-2 € of snow expected. Rain/snow line should climb as high as 1,500′. Winds will be in the 10-15 mph range out of the East and temperatures at 1,000′ will rise into the high 30s F.

The extended outlook is showing more of the same as we move into the work week. Circulation around the aforementioned system in the Gulf will bring multiple rounds of precip, clouds and mild temps through at least Wednesday.

PRECIPITATION 24-hour data (6am – 6am)

	Temp Avg (F)	Snow (in)	Water (in)	Snow Depth (in)
Center Ridge (1880′)	30	2/rain	.2	60
Summit Lake (1400′)	33	0	0	10
Alyeska Mid (1700′)	33	6/rain	.9	37

RIDGETOP 24-hour data (6am – 6am)

	Temp Avg (F)	Wind Dir	Wind Avg (mph)	Wind Gust (mph)
Sunburst (3812′)	24	ENE	17	39
Seattle Ridge (2400′)	27	n/a	15	31

Observations

Recent Observations for Turnagain Pass

Date	Region	Location	Observer
05/22/23	Turnagain	Avalanche: Tincan	Nick D'Alessio
05/12/23	Turnagain	Avalanche: Tincan, Sunburst, Magnum, Cornbiscuit	Heather Thamm
05/07/23	Turnagain	Observation: Tincan – Bear Tracks	CNFAIC Staff
05/05/23	Turnagain	Observation: Seattle Ridge	AS/ WW Forecaster
05/02/23	Turnagain	Observation: Cornbiscuit	Schauer/ Sturgess Forecaster
05/02/23	Turnagain	Observation: Seward Hwy Turnagain Pass	Joel Curtis
04/30/23	Turnagain	Observation: Magnum	Ayla, Kit Crosby, Barton
04/29/23	Turnagain	Observation: Tincan	John Sykes
04/28/23	Turnagain	Avalanche: Taylor Pass/Pastoral	Schauer/ Creighton Forecaster
04/28/23	Turnagain	Avalanche: Tincan	Andy Moderow

Riding Areas

Updated Thu, June 01st, 2023

Status of riding areas across the Chugach NF is managed by the Glacier and Seward Ranger Districts, not avalanche center staff. Riding area information is posted as a public service to our users and updated based on snow depth and snow density to prevent resource damage at trailhead locations. Riding area questions contact: mailroom_r10_chugach@fs.fed.us

Area	Status	Weather & Riding Conditions
Glacier District
Johnson Pass	Closed	Closed May 15.
Placer River	Closed	Closed May 15.
Skookum Drainage	Closed	Will close to motorized use on April 1, 2023 per the National Forest Plan.
Turnagain Pass	Closed	Will close on June 1.
Twentymile	Closed	Scheduled closure May 1.
Seward District
Carter Lake	Closed	Scheduled closure May 1.
Lost Lake Trail	Closed	Scheduled closure May 1.
Primrose Trail	Closed	Scheduled closure May 1.
Resurrection Pass Trail	Closed	Closed to motorized use for the 2022/23 winter season per Forest Plan. Open next season.
Snug Harbor	Closed	Extended opening until May 15.
South Fork Snow River Corridor	Closed	Scheduled closure May 1.
Summit Lake	Closed	Scheduled closure May 1.