Fri, January 13, 2017 Turnagain Pass Avalanche Forecast

Fri, January 13th, 2017

Alpine
Above 2,500'

Considerable (3)

Treeline
1,000'-2,500'

Moderate (2)

Below Treeline
Below 1,000'

Moderate (2)

Alpine Above 2,500'		Considerable (3)
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

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

It’s official – after a two-week dry spell, snow is falling this morning!! Although there’s only been around an inch so far, by this evening we could get up to 8-10″ in favored locations and 4-6″ in un-favored locations. Plus, an additional 4-6″ is possible overnight tonight. It will be one of those days to keep close tabs on how much new snow has fallen and how hard is it snowing. This will directly influence the avalanche hazard. The new snow is falling on a variety of old surfaces, including slick hard wind slabs/crust and soft faceted snow. Despite the myriad of different surfaces, expect bonding of the new snow to initially be poor.

Upper-elevation slopes in the Alpine are likely to be obscured today, but this is the terrain most suspect for receiving enough snow (up to 8+”) along with winds strong enough to form wind slabs that release naturally. If you find yourself in this situation, expert level snowpack assessment is necessary for entering avalanche terrain. Mid-elevation slopes and areas in the trees are more likely to receive less snow (4-6″) and little wind. In this terrain, naturally occurring avalanches are unlikely but human triggered shallow soft slabs and sluffs, the depth of the new snow, may be possible on the steeper slopes.

What to watch for:

How much new snow are you traveling through?
Heavy snowfall, strong winds?
Cracking in the new snow?
Are you traveling under an avalanche path that may be loading with snow above you?

Stepping off the skin track or jumping off your snowmachine to do quick hand pits will be a great tool for sussing out new snow depth and bonding. If skies are clear enough, look for loose snow avalanches in the steep terrain and keep your situational awareness up as the day progresses!

Photo below: An example of the pre-existing snow surface that the new snow is falling on – old hard wind slabs/crusts. Very weak faceted snow sits under these hard slabs and crusts. Once the storm snow bonds with the crust we could see avalanches breaking in the faceted snow beneath (will we get enough of a load for this? a focused question for this weekend).

Additional Concern

Glide Avalanches

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.

More info at Avalanche.org

Warming temperatures associated with the Southerly flow may enhance glide activity. Glide cracks have been slowing opening this week; though we have not seen/heard of any new cracks releasing. Keep an eye out for cracks, which is difficult with new snow and wind, and limit time underneath them.

Weather

Fri, January 13th, 2017

Yesterday was our last clear sky day with temperatures in the single digits in valley bottoms and the teens-20’s in the upper elevations. Ridgetop winds picked up later in the day from the Southeast to the 10mph range.

Overnight, clouds filled in and light snowfall began around 3-4am. Roughly a trace to an inch is being reported at stations this morning, including snow to sea level. Ridgetop winds have bumped up to 15-20mph with gusts into the 30’s. Temperatures have climbed dramatically at sea level as the inversion has been scoured away (28-30F at sea level, mid-20’s at the mid-elevations and mid-teens at the Ridgetops).

Today, we are expecting anywhere from 4-8+” of new snow and another 4-6″ tonight. Although temperatures have warmed dramatically, we should still see mostly snow to sea level with this event. Ridgetop temperatures will be in the mid-20’s F. Ridgetop winds are likely to increase more today into the 20-40mph range with gusts into the 50’s.

Tomorrow the system looks to move out and skies begin to break up as a cold and dryer North flow heads our way.

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

	Temp Avg (F)	Snow (in)	Water (in)	Snow Depth (in)
Center Ridge (1880′)	21	trace	0	33
Summit Lake (1400′)	10	0	0	11
Alyeska Mid (1700′)	20	0.3	0.1	21

RIDGETOP 24-hour data (6am – 6am)

	Temp Avg (F)	Wind Dir	Wind Avg (mph)	Wind Gust (mph)
Sunburst (3812′)	16	E	9	30
Seattle Ridge (2400′)	17	SE	17	35

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.