Sat, November 08, 2014 Turnagain Pass Avalanche Forecast

Sat, November 8th, 2014

Alpine

Above 2,500'

0 - No Rating

Treeline

1,000'-2,500'

0 - No Rating

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. 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

Wet Loose

Wet Loose

Wet Loose avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.

More info at Avalanche.org

Wet avalanches: Rain falling off-and-on up to 1800′ has weakened our 2-3′ snowpack and everything from wet loose, wet slab and glide avalanches have been reported. All of these reports have come in today (Saturday) and avalanche size has been described as small to medium. These are releasing on all aspects and elevations around 3,000′ and below.

As stated in the bottom line, be cautions of runout zones and areas under/near glide cracks where an avalanche occurring above could run down into your location.

Glide avalanches and cracks in the Girdwood area (Virgin Valley) above. Photo taken by Tim Glassett ADOT&PF.

Avalanche Problem 2

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

Dry avalanches: Above 3,000′ in the alpine terrain where it is snowing and blowing – classic stormy weather with little visibility – natural storm snow avalanches are likely. These come in the form of wind slabs, storm slabs and loose snow avalanches. Though winds are predominantly from the East, all aspects are suspect that harbor snow.

If you are debating getting out in the higher elevation backcountry to where it’s snowing, beware that natural avalanches are possible. Even if the skies clear and the snow stops be VERY suspect of triggering an avalanche. With weak snow on the ground earlier this month, the new storm snow may take several days to gain strength. Watch out for strong (harder) snow over weak (softer) snow – these are ingredients for a slab avalanche. Digging or poking in the snow with your pole can be very useful for sussing out this bad combination.

It looks like it will keep snowing up high for another few days – possibly this will begin to fill the cracks on the glaciers and set down a good base for the year?!

Weather

Sat, November 8th, 2014

November is coming in warm, wet and windy. We have had precipitation for 6 of the first 7 days of November and another several more days on the way. This is due to Super Typhoon Nuri that has evolved into a strong low pressure system centered in the Bearing that has shifted the storm track right to Southcentral AK. See image below from the NWS.

This is good news for the alpine elevations above treeline where it is snowing but for the lower elevations, not so much. The rain/snow line has been hovering between 1500 and 1800 feet and is expected to rise with warmer and wetter air masses moving in as the storm track dips further south.

Since Halloween night we have seen 25″ of snow and 3″ of water equivalent at the Turnagain Pass SNOTEL. This has been in two storm intervals. The first being colder 10/31-11/3 (12″ snow and 1.2″ water) and the second being warmer with a rain/snow mix 11/5-11/7 (13″ snow and 1.7 water). Winds have been strong out of the East with averages 20-25mph and gusts to 50mph.

As we head into this week expect rain to continue up to 1500-2500′ and snow above. Models are showing around 2″ of precipitation from now (11/8 through Monday 11/10).

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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