Fri, April 05, 2019 Turnagain Pass Avalanche Forecast

Fri, April 5th, 2019

Alpine
Above 2,500'

Moderate (2)

Treeline
1,000'-2,500'

Moderate (2)

Below Treeline
Below 1,000'

Moderate (2)

Alpine Above 2,500'		Moderate (2)
Treeline 1,000'-2,500'		Moderate (2)
Below Treeline Below 1,000'		Moderate (2)

Danger Scale:

No Rating (0)

Low (1)

Moderate (2)

Considerable (3)

High (4)

Extreme (5)

Avalanche Problem 1

Glide Avalanches
Almost Certain

Very Likely

Likely

Possible

Unlikely

Likelihood
Historic (D4-5)

Very Large (D3)

Large (D2)

Small (D1)

Size

Glide Avalanches

Glide Avalanches are the release of the entire snow cover as a result of gliding over the ground. Glide avalanches can be composed of wet, moist, or almost entirely dry snow. They typically occur in very specific paths, where the slope is steep enough and the ground surface is relatively smooth. They are often proceeded by full depth cracks (glide cracks), though the time between the appearance of a crack and an avalanche can vary between seconds and months. Glide avalanches are unlikely to be triggered by a person, are nearly impossible to forecast, and thus pose a hazard that is extremely difficult to manage.

Likelihood of Avalanches

Terms such as "unlikely", "likely", and "certain" are used to define the scale, with the chance of triggering or observing avalanches increasing as we move up the scale. For our purposes, "Unlikely" means that few avalanches could be triggered in avalanche terrain and natural avalanches are not expected. "Certain" means that humans will be able to trigger avalanches on many slopes, and natural avalanches are expected.

Size of Avalanches

Avalanche size is defined by the largest potential avalanche, or expected range of sizes related to the problem in question. Assigned size is a qualitative estimate based on the destructive classification system and requires specialists to estimate the harm avalanches may cause to hypothetical objects located in the avalanche track (AAA 2016, CAA 2014). Under this schema, "Small" avalanches are not large enough to bury humans and are relatively harmless unless they carry people over cliffs or through trees or rocks. Moving up the scale, avalanches become "Large" enough to bury, injure, or kill people. "Very Large" avalanches may bury or destroy vehicles or houses, and "Historic" avalanches are massive events capable of altering the landscape.

Signal Word	Size (D scale)	Simple Descriptor
Small	1	Unlikely to bury a person
Large	2	Can bury a person
Very Large	3	Can destroy a house
Historic	4 & 5	Can destroy part or all of a village

More info at Avalanche.org

Cooler temperatures over the region have put a halt on the wet avalanche issues we had last week. Many slopes are covered with crusts and the avalanche danger has decreased dramatically. Despite this, the pesky glide avalanche problem has not gone away and is our main concern for anyone headed into the backcountry. Cracks keep opening up and releasing in popular areas. Humans do not trigger glide avalanches, which makes the problem unpredictable as they can avalanche at any time. The good thing is we can watch for, and avoid, being under opening cracks. This is a case of ‘don’t be caught in the wrong place at the wrong time’. These slides, even small ones, are extremely destructive.

Glide avalanche on Magnum’s SW face (PMS Bowl), releasing Tues Apr 2nd. This is a heavily traveled slope and an example of how a person may be caught in the wrong place at the wrong time.

Additional Concern

Normal Caution

Normal Caution

Normal Caution means triggering an avalanche is unlikely but not impossible.

More info at Avalanche.org

Other than the creepy glide avalanche issue, the mountains are in a Normal Caution regime as far as avalanche danger. This means human triggered avalanches are unlikely. Some things to watch for and keep in mind if headed out today:

LOOSE WET: If slopes in the sun (and out of the breeze) heat up enough today, wet loose sluffs could be triggered this afternoon/evening.

CORNICES: Cornices remain very large along some ridgelines in the alpine. Give them a wide berth and avoid travel directly below them, especially in the heat of the day.

South of Turnagain in Summit Lake and the interior Kenai Peninsula the snowpack is very thin with a poor structure. Triggering a slab 2-3’ deep is unlikely, but not out of the question. The most suspect slopes are in the alpine above 3000’ – on shaded aspects any time of the day or on steep solar aspects late in the afternoon if the surface crusts soften.

Weather

Fri, April 5th, 2019

Yesterday: Mostly cloudy skies were over the area with light rain in Girdwood (0.1″) and Portage (0.4″). Ridgetop winds over the past 24-hours have been light to moderate from the east averaging ~10mph with gusts into the 20’s mph. Temperatures have been steady in the 20’sF along ridgelines and in the 30’sF at 1,000′. Cloud cover overnight has limited cooling in valley bottoms and low elevation stations are reporting low 30’sF.

Today: Partly sunny skies are expected today before clouds and light rain move back in tonight. Ridgetop winds are forecast to remain in the 10-15mph range with gusts to 30mph from an easterly direction. Temperatures look to stay mild, climbing to 40F at 1,000′ and the upper 20’sF along ridgelines.

Tomorrow: Stormy weather is expected as a low pressure spinning in the Gulf pushes a front over the Eastern Turnagain Arm. Rain falling up to 1,500′ or so is expected (possibly higher) with water amounts in the .25 – 1″ range. This equates to roughly 2-6″ of snow falling in the higher elevations. Ridgetop winds should pickup from the east as well. At this point, Sunday looks to remain cloudy and wet as the front stalls over before heading out possibly Monday. Stay tuned!

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

	Temp Avg (F)	Snow (in)	Water (in)	Snow Depth (in)
Center Ridge (1880′)	33	0	0	64
Summit Lake (1400′)	33	0	0	21
Alyeska Mid (1700′)	32	0	0.1	58

RIDGETOP 24-hour data (6am – 6am)

	Temp Avg (F)	Wind Dir	Wind Avg (mph)	Wind Gust (mph)
Sunburst (3812′)	22	NE	11	26
Seattle Ridge (2400′)	27	SE	6	18

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.