Sun, January 21, 2024 Turnagain Pass Avalanche Forecast

Sun, January 21st, 2024

Alpine

Above 2,500'

2 - Moderate

Treeline

1,000'-2,500'

2 - Moderate

Below Treeline

Below 1,000'

1 - Low

Mon, January 22nd, 2024

Alpine

Above 2,500'

2 - Moderate

Treeline

1,000'-2,500'

2 - Moderate

Below Treeline

Below 1,000'

1 - Low

Mon, January 22nd, 2024

Alpine

Above 2,500'

2 - Moderate

Treeline

1,000'-2,500'

2 - Moderate

Below Treeline

Below 1,000'

1 - Low

0 - No Rating

1 - Low

2 - Moderate

3 - Considerable

4 - High

5 - Extreme


Travel Advice	Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.	Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.	Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding, and conservative decision-making essential.	Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.	Extraordinarily dangerous avalanche conditions. Avoid all avalanche terrain.
Likelihood of Avalanches	Natural and human-triggered avalanches unlikely.	Natural avalanches unlikely; human-triggered avalanches possible.	Natural avalanches possible; human-triggered avalanches likely.	Natural avalanches likely; human-triggered avalanches very likely.	Natural and human-triggered avalanches certain.
Avalanche Size and Distribution	Small avalanches in isolated areas or extreme terrain.	Small avalanches in specific areas; or large avalanches in isolated areas.	Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas.	Large avalanches in many areas; or very large avalanches in specific areas.	Very large avalanches in many areas.

Recent Avalanches

With the exception of the ongoing glide avalanche cycle and some avalanches triggered by falling cornices on Friday, we have not seen any new slab avalanche activity in our advisory area since last Sunday, Jan. 14. Yesterday Skiers in Portage observed a very large avalanche that occurred sometime over the past week between the Burns and Portage Glaciers, which would be just outside of our forecast zone.

Large avalanche near Portage that was seen yesterday but likely occurred during last week’s wind event. Photo: Kit Barton, 01.20.2024

Avalanche Problem 1

Glide Avalanches
N E S W NW NE SE SW

Aspect/Elevation
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.

Aspect/Elevation of the Avalanche Problem

Specialists develop a graphic representation of the potential distribution of a particular avalanche problem across the topography. This aspect/elevation rose is used to indicate where the particular avalanche problem is thought to exist on all elevation aspects. Areas where the avalanche problem is thought to exist are colored grey, and it is less likely to be encountered in areas colored white.

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

With another day of quiet weather on the way today, our main concern for now remains the active glide cycle that has been unfolding since late December. We continue to see new glide activity from Girdwood to Seward, with large glide cracks opening up and releasing in very popular areas. It is impossible to predict the timing of a glide avalanche, but with all of the action we’ve seen over the past few weeks we are expecting to see more today. These avalanches are large and destructive since they involve the entire season’s snowpack, now 5-7′ deep on average. Luckily, the cracks that open up prior to a glide avalanche make this problem easy to recognize, and a lot easier to manage than some other trickier avalanche problems. Avoid spending any time under an open glide crack since they release spontaneously. If your intended route crosses under a slope with a glide crack above, consider an alternate route if at all possible. If you can’t find a way around it, travel quickly to minimize your exposure time and move one at a time while you cross under the hazard. Be sure to plan your safe spots carefully- these avalanches are very big and can run long distances.

If it weren’t for these darn glide avalanches we would probably be at low danger right now, keeping in mind all of the normal caution safe travel practices. There are probably isolated and small wind slabs lurking out there near some lonely ridgetops, but we are not expecting to see people triggering avalanches until we see another loading event. If you are thinking about getting into steeper terrain while we are in this extended period of calm weather and generally stable snow, be sure to reduce the consequences of some outlier avalanche by travelling one at a time in steep terrain and watching your partners from safe spots outside of avalanche runout zones. Although the snowpack is generally stable, we’re still assessing conditions before getting into big terrain- using travel tests and test slopes just to make sure we’re not missing anything before we jump into steeper slopes. We’ve seen multiple reports of falling cornices over the past few days, which is a good reminder to limit spending any time under them.

Active glide cracks in the Lynx Creek area. Yikes. 01.21.2024

This very large cornice is peeling away from the ridgeline above Wolverine, commonly referred to as ‘Flying Cornice’. This cornice is hanging on by a thread, and it would be impossible to recognize how close it is to releasing if you were below it. Photo: Matti Silta, 01.20.2024

Weather

Sun, January 21st, 2024

Yesterday: We saw another day of clear and calm weather yesterday. Temperatures were once again warmer at upper elevations, with high temperatures in the upper 20s F at ridgetops and in the single digits to low teens F in the valleys. Weather stations this morning are showing the coldest temperatures in the past 24 hours; in the single digits above and below 0 F.

Today: A weak system will be passing through today, bringing partly to mostly cloudy skies but no significant weather otherwise. Winds will be light with variable direction but should stay less than 10 mph, and we may see a few snowflakes later in the day but no accumulation is expected. The temperature inversion that has been keeping temperatures mild at upper elevations has broken down, and we are expecting high temperatures in the low to mid teens F with lows dropping down into the single digits above and bleow zero F.

Tomorrow: High pressure moves back in tomorrow, with skies expected to clear through the day and winds to switch back to the west but remain light at around 5-10 mph. Temperatures will linger in the single digits above and below zero F, and no precipitation is expected.

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

	Temp Avg (F)	Snow Depth (in)
Center Ridge (1880′)	16	78
Summit Lake (1400′)	11	N/A
Alyeska Mid (1700′)	17	77
Bear Valley – Portage (132′)	0	–
Grouse Ck – Seward (700′)	8	50

RIDGETOP 24-hour data (6am – 6am)

	Temp Avg (F)	Wind Dir	Wind Avg (mph)	Wind Gust (mph)
Sunburst (3812′)	17	E	7	22
Seattle Ridge (2400′)	19	E	5	77

Observations

Recent Observations for Turnagain Pass

Date	Region	Location	Observer
10/27/24	Turnagain	Observation: Tincan	Michael Kerst
10/21/24	Turnagain	Observation: Turnagain Pass Road Observation	Trevor Clayton
10/19/24	Turnagain	Observation: Tincan – Below Todds Run	Andy Moderow
10/18/24	Turnagain	Observation: Taylor Pass	Eli Neuffer
10/15/24	Turnagain	Observation: Tincan Common	John Sykes Forecaster
10/14/24	Turnagain	Avalanche: Tincan	CNFAC Staff
05/13/24	Turnagain	Observation: Eddie’s, Sunburst, Seattle, Cornbiscuit, Pete’s South	H Thamm
05/13/24	Turnagain	Observation: Turnagain Pass non-motorized side	Amy Holman
05/12/24	Turnagain	Observation: Warm up Bowl	Tony Naciuk
05/07/24	Turnagain	Observation: Turnagain Pass Wet Slabs	A S

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