Wed, December 14, 2016 Turnagain Pass Avalanche Forecast

Wed, December 14th, 2016

Alpine

Above 2,500'

1 - Low

Treeline

1,000'-2,500'

1 - Low

Below Treeline

Below 1,000'

1 - Low

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

Normal Caution

Normal Caution

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

More info at Avalanche.org

While we patiently wait for the next snow event, folks continue to get out and enjoy the blue sky days and what snow we do have. To generalize, the snowpack above treeline is anywhere from 3-6′ thick on the North end of Turnagain Pass and 2-3′ thick on the South end the Pass (more snow typically falls on the North end because it’s closer to the Arm). Along the road the snowpack is anywhere form 6″ to 20″. It has been 14 days since our last snow event that added 6-10+”. The snowpack is generally stable and turning to sugar snow from the top down (near surface faceting) and in many thinner areas like Summit Lake, from the bottom up (forming depth hoar). Essentially, these cold days are creating a very weak foundation for the next load of snow.

If you are headed out today, watch for wind slabs near ridgelines that are sitting on weak faceted snow (we received a report describing a wind slab that collapsed but didn’t release yesterday in the Girdwood Valley). Additionally, watch for cornices and ‘facet’ sluffs on very steep terrain. Last, the ‘outlier’ slab avalanche that could fail mid-pack due to the Nov 16 buried surface hoar is worth keeping in the back of your head.

Weather

Wed, December 14th, 2016

It looks as though yesterday closed up the last of the single digit temperatures and bluebird skies. A large area of low pressure is pushing in and scouring out the cold air. Temperatures warmed up to the 15-25F range from valley bottoms to ridgetops overnight and ridgetop winds have remained light from a Westerly direction.

For today we should see mostly clear skies with some valley fog. Temperatures will remain in the 15-20F range in the parking lots and mid 20’sF along the ridgelines. Winds are expected to be Northwesterly around 5-10mph on the ridgelines.

Again, the more interesting news is this weekend and next week. If the stars align we should see snow accumulation as early as Thursday, and not only snow to sea level, but snow falling at Hatcher Pass. At his point, models are showing a Southwest flow direction for Thursday into Friday – favoring Hatcher Pass as well as Anchorage. The larger system for Sunday looks to favor Turnagain Pass.

Check out part of the National Weather Service’s long term discussion below:

“.LONG TERM FORECAST (Days 3 through 7…Fri through Tue)…

A pattern change remains on track for late this week into next
week …. will help to usher a train of fast-moving systems … This
will bring a moderating trend to temperatures……… as well as
increased precipitation chances, especially along the coastlines.
Trends suggest there may be ample snow opportunities inland
by early next week as well.”

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

	Temp Avg (F)	Snow (in)	Water (in)	Snow Depth (in)
Center Ridge (1880′)	18	0	0	20
Summit Lake (1400′)	16	0	0	5
Alyeska Mid (1700′)	20	0	0	9

RIDGETOP 24-hour data (6am – 6am)

	Temp Avg (F)	Wind Dir	Wind Avg (mph)	Wind Gust (mph)
Sunburst (3812′)	18	W	3	15
Seattle Ridge (2400′)	20	SW	4	14

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

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