Sun, December 25, 2016 Turnagain Pass Avalanche Forecast

Sun, December 25th, 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

All I want for Christmas is a big snow storm
A big snow storm
Just, a big snow storm…

Merry Christmas riders and skiers!!! It seems as though Santa has answered our wishes and brought us a long awaited ‘Chugach Storm’! Yes, it’s raining at sea level, but above 500′ there is sticky new snow blanketing the mountains. Unfortunately, this is too much to play with today as by this afternoon we could be up to 20+” of new snow in 24 hours.

STORM TOTALS in the upper elevations so far:

Turnagain Pass: 12″ and counting
Girdwood Valley: 12″ and counting
Summit Lake: 2-4″

EXPECTED AVALANCHE ACTIVITY: This is a text-book “rapid loading event”. Not only is 2′ of snow in 24 hours an avalanche maker in itself, this snow is falling on a VERY weak surface. The loose faceted snow combined with surface hoar (that we’ve been skiing/riding on the past several days) will act like ball bearings and inhibit the new snow from sticking to the mountainsides. Hence, widespread natural slab avalanches up to 2′ thick are likely and human triggered avalanches very likely. Winds should stay strong along with the snowfall through tonight and wind loaded slopes could harbor slabs as thick as 4′.

Treed areas such as the Tincan Trees: Storm snow slab avalanches 1-2′ 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.

Check out the Turnagain Pass Snowstake loop at the RWIS DOT station. Thanks to the DOT for getting this station up and running for the winter!

Weather

Sun, December 25th, 2016

During the past 24-hours we have seen the start to our ‘Christmas Storm’. Snow began falling at noon yesterday and totals up to 6am this morning are above and in the table below. Winds ramped up dramatically yesterday morning from the East and have remained in the 30’s mph with gusts over 60mph on the ridgetops. We have limited wind data with the Sunburst weather station down, but it’s no question the winds are very strong with this system. Temperatures have warmed from the teens to the mid-20’sF above the trees and into the low 30’sF at 1,000′. The rain/snow line looks to be hovering near 500′.

We are expecting another 10-12″ of snowfall today with around 1″ of water equivalent. Winds are expected to remain strong from the East in the 30’s mph with gusts to 75mph on the ridgetops. Temperatures look to stay warm with a rain/snow line remaining around 500′.

Tonight and tomorrow the system slowly moves out and we should see instability showers adding another few inches along with cooler temperatures.

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

	Temp Avg (F)	Snow (in)	Water (in)	Snow Depth (in)
Center Ridge (1880′)	27	12	0.8	36
Summit Lake (1400′)	30	2	0.2	9
Alyeska Mid (1700′)	28	8	0.7	24

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′)	22	SE	29	60

Observations

Recent Observations for Turnagain Pass

Date	Region	Location	Observer
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
04/29/24	Turnagain	Avalanche: Turnagain aerial obs	Tully Hamer
04/27/24	Turnagain	Observation: Johnson Pass	Noah Mery
04/23/24	Turnagain	Observation: Turnagain Sunny Side	Travis SMITH
04/21/24	Turnagain	Observation: Bertha Creek	Anonymous
04/20/24	Turnagain	Avalanche: Spokane Creek	Schauer/ Mailly Forecaster
04/16/24	Turnagain	Observation: Cornbiscuit	Krueger / Matthys Forecaster

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