Sun, February 24, 2013 Turnagain Pass Avalanche Forecast

Sun, February 24th, 2013

Alpine

Above 2,500'

2 - Moderate

Treeline

1,000'-2,500'

2 - Moderate

Below Treeline

Below 1,000'

2 - Moderate

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

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

Today’s main player in the avalanche game will be the wind. Yesterday’s new snow came in with strong east wind and though the wind died down overnight, it is forecast to pick back up today. Both lingering slabs formed yesterday, as well as fresh slabs today, will be the thing to watch out for. With the addition of a few inches of snow today, expect these slabs to be in the 8-16″ range. Keeping an eye out for active wind loading and cracking in the snow around you will be your best clue to finding and avoiding a wind slab.

Additional Concerns:

Loose snow avalanches: In areas without wind effect, kicking off sluffs on the steeper slopes should be expected. These are not likely to be large due to the modest amounts of new snow.

We received a bit of a refresher yesterday. 4-8” of new snow not only covered the upper elevations but made its way down to sea level as well. Below treeline riding conditions are drastically improving from a week ago and now harbor a few wind slab and loose snow avalanche concerns as well.

Avalanche Problem 2

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

The outlier. There are two layers buried below the surface that are worth mentioning: (1) facets above the late January crusts 3-6’ deep and (2) weak early season snow near the ground. Triggering one of these layers is most pronounced in areas with a shallow snowpack (i.e., the interior Kenai Mountains as well as thin slopes in the Turnagain/Girdwood zones). Keeping with safe travel practices and steering clear of thin areas are your best bet for avoiding one of these outliers.

Weather

Sun, February 24th, 2013

Yesterday’s modest storm brought snow to sea level and varying amounts to the region. The north side of Turnagain Pass through Girdwood picked up roughly 4-8 € while the east side of the Pass was about half that. Summit Lake looks to have seen 2-3 €. Winds associated were easterly averaging 20-30mph with gusts to the 50’s. Temperature was in the mid-teens at ridgetops and around 30F at sea level.

A brief break between systems overnight will be short lived as a weak front will bring a few more inches of snow and moderate east wind this afternoon. Temperatures are expected to remain in the mid-teens on ridgetops and near 30F at sea level

Lately, several of the low pressure systems that have been passing by have been far enough to the south to keep the warm air at bay and snow at sea level. This trend is expected to continue for several more days – good news for the lower elevations.

Fitz will issue the next advisory tomorrow morning, February 25^th.

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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