Sun, November 20, 2016 Turnagain Pass Avalanche Forecast

Sun, November 20th, 2016

Alpine
Above 2,500'

Considerable (3)

Treeline
1,000'-2,500'

Moderate (2)

Below Treeline
Below 1,000'

No Rating (0)

Alpine Above 2,500'		Considerable (3)
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

Persistent Slabs

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.

More info at Avalanche.org

What a weekend to begin the forecast season here at the CNFAIC. During the last two days we have had over 10 human triggered avalanches. One of these was on a popular low angled slope (Manitoba) in the Summit Lake area. Luckily, from what we know of, no one has been injured in any of these slides. A lost ski and pole on Friday from an individual caught and carried in Tincan Common Bowl seems to be the worst of it so far. With this, we have had 10 public observations in the last two days describing the events and details – thank you for making time to send us your information !!

The problem with the snowpack is a layer of buried surface hoar that sits below new snow from last Thursday. Areas on the North side of the Pass (Tincan and Eddies) saw 10-12″, while the Southern side (Sunburst and over to Summit Lake) saw 5-8+”, hence this buried surface hoar is anywhere from 5-12″ below the surface and is the thickness of slabs folks are triggering. Slabs are soft and releasing while people are riding them as well as being triggered remotely from above or the side.

Two notable characteristics of this avalanche problem:
1- Releasing on very low slope angles, angles in the 20’s (one was measured at 18 degrees!).
2- Running much further than expected

If you are headed out today, be very wary of any slope near treeline or above treeline that has not avalanched. Keep slope angles low and be aware of crossing under slopes above you. If the light gets poor (new snow and wind are expected tonight), be aware of your return route – as not to get suckered somewhere you don’t want to go. Today is another day to be extra conservative – we have a long and hopefully snowy season ahead.

Photo below: Human triggered soft slab avalanches on Sunburst.

Photo below: Human triggered avalanche just above treeline on Tincan. Note the debris that ran over the skin track. More on this report HERE.

Again, thank you to the many people submitting observations – if you haven’t done so already, take a few minutes and check them out.

Weather

Sun, November 20th, 2016

Partly cloudy skies yesterday gave way to some sunshine later in the day with valley fog up to 1,500′. There was no precipitation and temperatures were in the mid 20’s F. Winds were light and variable. Overnight, a trace to an inch of new snow fell at Turnagain Pass.

Today, Sunday, a short lived storm system will move in from the East. Skies are expected to become mostly cloudy by the end of the day with light snow beginning to fall. Ridgetop winds will be Easterly around 10mph and picking up tonight into the 25-35mph range. Overnight, we could see anywhere from 4-8″ of new snow. Temperatures will be in the 20’s F and it looks like snow should fall to sea level again – so cross your fingers!

On Monday, snowfall and wind are expected to tapper off by mid-day and temperatures cool slightly. It looks like we will have a break in weather Tuesday and into Wednesday with temperatures staying in the low 30’s at sea level and the mid 20’s in the mountains.

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

	Temp Avg (F)	Snow (in)	Water (in)	Snow Depth (in)
Center Ridge (1880′)	23	1	0.1	18
Summit Lake (1400′)	21	0	0	3
Alyeska Mid (1700′)	23	0	0	3

RIDGETOP 24-hour data (6am – 6am)

	Temp Avg (F)	Wind Dir	Wind Avg (mph)	Wind Gust (mph)
Sunburst (3812′)	19	East	5	18
Seattle Ridge (2400′)	21	N/A (sensor rimed)	N/A (sensor rimed)	N/A (sensor rimed)

Observations

Recent Observations for Turnagain Pass

Date	Region	Location	Observer
05/21/22	Turnagain	Avalanche: Magnum, Lipps and Tincan	CNFAIC Staff
05/17/22	Turnagain	Avalanche: Sunburst	CNFAIC Staff
05/17/22	Turnagain	Observation: Tincan Ridge	Joe Kurtak
05/11/22	Turnagain	Avalanche: Cornbiscuit and Magnum west faces	CNFAIC Staff Forecaster
05/07/22	Turnagain	Observation: Granddaddy	Kit Barton
04/29/22	Turnagain	Observation: Sunburst wx station	AS/ MM/ AM/ NH
04/28/22	Turnagain	Observation: More Turnagain Pass/Summit Lake wet slab activity	Alex Marienthal
04/27/22	Turnagain	Observation: Magnum	Sykes / Buttrick Forecaster
04/27/22	Turnagain	Observation: Girdwood/Summit/Turnagain Road obs	A S
04/24/22	Turnagain	Avalanche: Seattle Ridge – large glide avalanche on Repeat Offender path	CNFAIC Staff Forecaster

Riding Areas

Updated Fri, May 13th, 2022

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 as of May 1 per Forest Plan.
Placer River	Closed	Closed as of April 25th due to insufficient snow coverage.
Skookum Drainage	Closed	Closed as of April 1st per Forest Plan.
Turnagain Pass	Open	Open. Extended opening through May 31.
Twentymile	Closed	Closed as of April 6th due to insufficient snow coverage.
Seward District
Carter Lake	Closed	Closed as of May 1 per Forest Plan.
Lost Lake Trail	Closed	Closed as of May 1 per Forest Plan.
Primrose Trail	Closed	Closed as of May 1 per Forest Plan.
Resurrection Pass Trail	Closed	Closed as of May 1 per Forest Plan.
Snug Harbor	Closed	Closed as of May 1 per Forest Plan.
South Fork Snow River Corridor	Closed	Closed as of May 1 per Forest Plan.
Summit Lake	Closed	Closed as of May 1 per Forest Plan.