Mon, December 26, 2016 Turnagain Pass Avalanche Forecast

Mon, December 26th, 2016

Alpine

Above 2,500'

4 - High

Treeline

1,000'-2,500'

4 - High

Below Treeline

Below 1,000'

3 - Considerable

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.

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

Yesterday natural avalanches 2 ft. deep were observed. These were long running and large enough to bury and kill a person. Cracking and collapsing (whumpfing) were also observed.

Red flags… Rapid loading = Expect dangerous avalanches.

STORM TOTALS in the upper elevations so far:

Turnagain Pass: 30+” and counting, 2.8″ of H2O
Girdwood Valley: 20+” and counting, 1.6″ of H2O
Summit Lake: 4-6″, .4″ of H2O

Snow continues to fall with another 1-4″ inches expected today. 16″- 20″ of snow was measured yesterday on Turngagain Pass. An additional 10+ inches has fallen since then. All of this new snow is forming thick slabs, especially in the alpine where consistent easterly winds have been blowing into the 40’s. The weak surface snow and weak snowpack have been rapidly loaded. Expect natural avalanches today and that triggering an avalanche is very likely on any slopes over 30 degrees. Avalanches have the potential to be long running and could be remotely triggered. Avoid travel underneath avalanche terrain as well. This includes the Seattle Ridge up-track and all slopes, gullies and runout zones.

This needs to be highlighted again today:

Treed areas such as the Tincan Trees: Storm snow slab avalanches 2-3′ thick are likely to be triggered in the trees. The new snow is denser than the underlying old snow – creating an upside down and unstable snowpack. Avoiding slopes over 30 degrees in treed areas is also recommended. Due to the weak faceted snow below the new snow the snowpack is “bottomless”. Movement through the snow was challenging yesterday and will only be more of a struggle today.

Travel in avalanche terrain is NOT recommended. Deep, dangerous avalanches are likely. BE PATIENT.

Natural avalanche in the Snake Pit on Tincan, 12.25.16. The next gully over also slid.

Weather

Mon, December 26th, 2016

Yesterday skies were obscured and it snowed or rained depending on elevation throughout the day with periods of heavy precipitation. Easterly winds were in 20s gusting into the 40s. Temperatures were in the 20Fs at ridge tops and in 30s in the valleys. Rain/snowline fluctuated around 500′. The storm continued overnight and temperatures are rising slightly this am.

Today will be cloudy and another 1-4″ of snow is forecasted to fall, rain below 400′. Temperatures are forecasted to hover around freezing, either above or below depending on elevation. Winds will remain easterly 5-15 mph with higher gusts in the alpine. The snow showers are forecasted to continue overnight into tomorrow with temperatures cooling and winds becoming calm.

Tomorrow is forecasted to be cloudy with a slight chance of snow showers, temperatures in the low 20Fs and light NW winds.

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

	Temp Avg (F)	Snow (in)	Water (in)	Snow Depth (in)
Center Ridge (1880′)	29	20	2	50 + (estimate)
Summit Lake (1400′)	31	2	.2	10
Alyeska Mid (1700′)	31	10	.9	32

RIDGETOP 24-hour data (6am – 6am)

	Temp Avg (F)	Wind Dir	Wind Avg (mph)	Wind Gust (mph)
Sunburst (3812′)	Under repair	Under repair	Under repair	Under repair
Seattle Ridge (2400′)	24	rimed	rimed	rimed

Observations

Recent Observations for Turnagain Pass

Date	Region	Location	Observer
04/16/24	Turnagain	Observation: Cornbiscuit	Krueger / Matthys Forecaster
04/15/24	Turnagain	Observation: Taylor Pass	John Sykes Forecaster
04/15/24	Turnagain	Observation: Seward Highway – Tern Lake to Portage	Joel Curtis
04/14/24	Turnagain	Observation: Sunburst	T. Olsen-Lund, R. Sullivan I. Adams
04/14/24	Turnagain	Observation: Turnagain Pass Snomo	K. Gallaher
04/13/24	Turnagain	Observation: Spokane Creek	Everet Megli
04/11/24	Turnagain	Observation: Tincan	John Sykes Forecaster
04/10/24	Turnagain	Avalanche: Seattle Ridge	Schauer/ Keeler Forecaster
04/10/24	Turnagain	Observation: Cornbiscuit South Face	Todd Kelsey
04/10/24	Turnagain	Avalanche: Tincan	N. Dumont J. Carlberg

Riding Areas

The riding areas page has moved. Please click here & update your bookmarks.