Fri, April 17, 2015 Turnagain Pass Avalanche Forecast

Fri, April 17th, 2015

Alpine
Above 2,500'

Considerable (3)

Treeline
1,000'-2,500'

Considerable (3)

Below Treeline
Below 1,000'

No Rating (0)

Alpine Above 2,500'		Considerable (3)
Treeline 1,000'-2,500'		Considerable (3)
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

Wind Slabs

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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

Today up to 5” of new snow combined with moderate winds (20-30mph) from the Northeast could form isolated wind slabs up to 8″ thick on leeward terrain features. On shaded features in the Alpine (where a surface crust doesn’t exist) these wind slabs could stress the most recent storm slab up to 2’ thick. At lower elevations these wind slabs will be forming on a surface crust and could be tender.

Wind slab thickness will depend on how much snow falls today. A large low-pressure system is expected to push into our region this evening. Winds are likely to increase into the 40s mph and an additional 8” of snow is expected this evening. Should this storm arrive earlier then expected the avalanche danger could increase to CONSIDERABLE by early evening.

Careful snowpack and terrain evaluation are required for every group traveling in the mountains. If you find that the snowfall intensity and strong winds are causing rapid loading, keep your slope angles below 35° and avoid large open slopes.

Deeper Persistent Layers:

There are several old weak layers burried deep within our snowpack. Today’s moderate winds and new snow will likely make visibility challenging. Should a window apear making steeper more extreme terrain appealing, condsider that we don’t have a lot of current info about these layers. It has been 6 days since activity has been observed in these deeper layers, but it is uncertain how much additional loading + the right trigger will re-awaken them.

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

Springtime requires us to pay close attention to how the snow changes throughout the day. We have seen intense solar affect almost every day. This is a reminder that our current snowpack can change dramatically from the morning into the afternoon. Although sun isn’t supposed to be an issue today, it has suprised us over the last few weeks and subtle warming affects are playing more of a role than noticed.

As this storm moves into our area expect rain/snow line to start moving up in elevation and could be as high as 1500’ by Saturday morning. Should the lower elevation snow become wet and saturated wet loose avalanches will be possible.

Turnagain Pass looks more like winter than it has most of the season. The Forest Service is closely monitoring the snow depths and snow density on the motorized side of the road for a potential motorized opening. There isn’t quite enough coverage yet to protect the vegetation below, but check back here should this next storm come in cold.

Weather

Fri, April 17th, 2015

Yesterday cloud cover in the morning was thick and in the afternoon skies became partly sunny at times. Scattered snow and rain showers were observed throughout the day with little to no accumulation. Temperatures were between 30-40F at lower elevations and averaged in the mid 20s F along ridgetops. Winds were calm in the morning increasing to 15-20 mph from the Northeast in the afternoon.

Overnight temps at lower elevations dipped just below freezing and only a trace of precipitation was recorded. Winds were moderate 15-25mph from the Northeast along ridgetops.

Showery rain and snow conditions are expected throughout today. Winds will increase in the afternoon as a large low-pressure system arrives tonight bringing rain and strong winds. Rain/snow line may be as high as 1500′ by Saturday.

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

	Temp Avg (F)	Snow (in)	Water (in)	Snow Depth (in)
Center Ridge (1880′)	34	0	0	75
Summit Lake (1400′)	34	0	0	12
Alyeska Mid (1700′)	34	2	.19	43

RIDGETOP 24-hour data (6am – 6am)

	Temp Avg (F)	Wind Dir	Wind Avg (mph)	Wind Gust (mph)
Sunburst (3812′)	24	ENE	13	45
Seattle Ridge (2400′)	26	n/a	17	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 Sat, September 23rd, 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	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.
Placer River	Closed	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.
Skookum Drainage	Closed	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.
Turnagain Pass	Closed	Scheduled opening on the Wednesday before Thanksgiving per Chugach National Forest plan. Subject to adequate snow cover.
Twentymile	Closed	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.
Seward District
Carter Lake	Closed	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.
Lost Lake Trail	Closed	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.
Primrose Trail	Closed	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.
Resurrection Pass Trail	Closed	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.
Snug Harbor	Closed	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.
South Fork Snow River Corridor	Closed	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.
Summit Lake	Closed	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.