Thu, March 16, 2017 Turnagain Pass Avalanche Forecast

Thu, March 16th, 2017

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

What a long strange trip it’s been without any measurable precipitation… 22 days for those that are counting! Surface conditions are made up primarily of thin crusts, hard wind board on ridges and near surface facets (recycled powder) in favored areas sheltered from the recent winds. Avalanche concerns to keep in mind today if venturing out:

Wind Slabs: Some fresher wind slabs likely formed during Tuesday’s wind event and could be tender, though likely small in size. Watch for shooting cracks indicating recently loaded slopes and fresher wind slabs. Older, stiffer wind slabs such as the one triggered on Seattle ridge last weekend will be less likely to trigger by a skier or snowmachiner today. Smooth pillowed snow on steep unsupported features or in rocky areas will be the most suspect of areas for someone to initiate an old wind slab.

Loose Snow Avalanches (Sluffs): Dry sluffs on steep slopes are probable and have been fast moving this week. Keep terrain choices and potential consequences in mind when managing sluffs.

Glide Avalanches: Glide cracks continue to slowly open above popular terrain on Seattle Ridge and in other zones across the advisory area. These may release at any time. Minimize exposure time spent under visible cracks.

Cornices: Cornices should always be given an extra wide berth if travelling along a corniced ridge. Like glide cracks, minimize your exposure time spent under these backcountry bombs.

Persistent Slabs and Deep Slabs: There are various weak layers in our thin snowpack. Buried surface hoar sits 1-3+’ below the surface and faceted snow sits in the mid and base of the pack. Given plenty of time and a lack of changing weather, these weak layers (with varying degrees of strength) are in a ‘dormant stage’. Although unlikely, an avalanche breaking deeper in the pack isn’t completely out of the question in areas such as Johnson Pass, Lynx Creek and in parts of Girdwood Valley (especially around Crow Pass). A cornice fall or glide crack release could also be a large enough trigger to wake up one of these persistent slabs.

Wind-buffed Magnum ridge with a sizeable cornice still in-tact over PMS bowl. photo: Conrad Chapman

Thin sun-crust capping chained Facets at 2,400′ yesterday on Magnum. photo: Conrad Chapman

Weather

Thu, March 16th, 2017

High clouds making for a grey-bird day were a welcome €˜change’ for many a backcountry enthusiasts in south-central Alaska yesterday. Unfortunately those clouds weren’t of the precip-producing type. Temps continue to be unseasonably cool with a high topping out in the single digits at 1880′ on Center ridge. Winds were light to moderate from the NW at ridgetop levels.

High clouds today will give way to mostly sunny skies by this afternoon. Expect light winds from the NNE today as the worst of the blow appear to be over (at least for now). Temps will again start out cool but should warm a bit more today to the low 20’s F at 1,000′. No measurable precip is expected.

Expect mostly clear skies, light winds and cool overnight temps recovering to the 20’s F thru the weekend. We’ve got some “chances of snow” materializing in the longer term forecast by early next week. Stay tuned!

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

	Temp Avg (F)	Snow (in)	Water (in)	Snow Depth (in)
Center Ridge (1880′)	6	0	0	59
Summit Lake (1400′)	9	0	0	29
Alyeska Mid (1700′)	9	0	0	56

RIDGETOP 24-hour data (6am – 6am)

	Temp Avg (F)	Wind Dir	Wind Avg (mph)	Wind Gust (mph)
Sunburst (3812′)	0	WNW	5	16
Seattle Ridge (2400′)	3	N	6	20

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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