Wed, January 28, 2015 Turnagain Pass Avalanche Forecast

Wed, January 28th, 2015

Alpine

Above 2,500'

2 - Moderate

Treeline

1,000'-2,500'

1 - Low

Below Treeline

Below 1,000'

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. Dangerous avalanche conditions.	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

Wind Slabs

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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

Temperatures have been relatively cool (single digits to teens F) over the last four days. Turnagain Pass has about 4-6” of slightly aged, low-density snow available for transport. This morning winds have increased along ridgetops averaging 15mph with gusts into the low 30’s. The prominent wind direction on Seattle Ridge has been Southwesterly and Easterly on Sunburst. If winds continue as forecasted today this combination of loose dry snow and moderate winds could be just enough to form wind slab pockets up to 6” thick. Be on the look out for tender areas of wind-stiffened snow. These shallow slabs will be small, not likely to bury a person, but could be just enough to knock you off your feet and take you for a ride in terrain steeper than 35°.

Yesterday we received a report of a skier triggered soft slab 10” deep that propagated 75’ across a Western aspect, mid-slope near 5000’. This is outside of our normal forecast zone, but is worth noting for anyone planning to access remote terrain. Also Girdwood Valley, Portage, and Summit Lake have seen more wind exposure than Turnagain Pass in the last three days, therefore wind slab pockets could be more tender and easier to initiate on leeward features. Evaluate surface conditions as you travel today and watch for visible wind loading on terrain above you. This could be extra important for ice climbers in very steep terrain where natural wind slab avalanches could occur.

Additional Concern

Normal Caution

Normal Caution

Normal Caution means triggering an avalanche is unlikely but not impossible.

More info at Avalanche.org

Glide Cracks

No new significant glide activity has been observed over the last week. Due to the unpredictable nature of glide avalanches it is important to get a good look at the terrain you’re about to ski/ride to avoid traveling directly on the slab of a glide. See photo below. In general be quick if traversing direcly below glides to minimize your travel time in the run-out zone.

Close up of a glide crack on Magnum’s South face. This ski track crosses directly over this glide and appears to be from before Jan.24th with 2″ of new snow covering it.

Low snow coverage

Below 2000’ low snow coverage is deceiving with only a few inches of new snow covering rocks, ice and vegetation. Take your time getting in and out of the alpine today.

Weather

Wed, January 28th, 2015

Yesterday skies were sunny and clear with light variable winds averaging 5-10mph. No new precipitation was recorded and temperatures increased slightly from single digits into the mid teens to low 20’sF during the day.

Overnight ridgetop winds have increased, averaging 15mph with gusts into the low 30’s. Wind directions are variable based on location. As of this morning Sunburst wind direction is Easterly, and Seattle Ridge has more of a Southwesterly flow. Temperatures have remained in the teens (F) overnight and no precipitation has been recorded.

Today ridgetop winds are expected to remain moderate, averaging 15mph with gusts into the high 20’s to low 30’s from the Northeast. Temps will be in the low to mid 20’s F, with partly cloudy skies.

Tonight there is a chance for light precipitation, up to an 2 € of new snow at higher elevations and 1 € at sea level. Temperatures are expected to remain in the low to mid 20’s F and winds will remain moderate 15-25mph, mostly from the Northeast into the evening.

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

	Temp Avg (F)	Snow (in)	Water (in)	Snow Depth (in)
Center Ridge (1880′)	19	0	0	31
Summit Lake (1400′)	13	0	0	7
Alyeska Mid (1700′)	16	0	0	22

RIDGETOP 24-hour data (6am – 6am)

	Temp Avg (F)	Wind Dir	Wind Avg (mph)	Wind Gust (mph)
Sunburst (3812′)	16	E	6	25
Seattle Ridge (2400′)	17	Var	9	33

Observations

Recent Observations for Turnagain Pass

Date	Region	Location	Observer
11/16/23	Turnagain	Observation: Tincan Common	William Finley
11/14/23	Turnagain	Observation: Sunburst/Magnum	Adrian Beebee
11/14/23	Turnagain	Observation: Seattle Ridge	Schauer/ Creighton/ Ellis Forecaster
11/13/23	Turnagain	Avalanche: Tincan Trees	Eeva Latosuo
11/12/23	Turnagain	Observation: Sunburst	Schauer/ Creighton/ Nave Forecaster
11/12/23	Turnagain	Avalanche: Goldpan – avalanche	Mike Records
11/11/23	Turnagain	Observation: Tincan Common	Andy Moderow
11/11/23	Turnagain	Observation: Taylor Pass – Sunburst	Wadsworth / Stwertka
11/10/23	Turnagain	Observation: Tincan	Andrew Schauer Forecaster
11/10/23	Turnagain	Observation: Tincan Trees	Michael Kerst

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