Sat, March 02, 2019 Turnagain Pass Avalanche Forecast

Sat, March 2nd, 2019

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

After 8 days of brilliant sunny skies and springtime temperatures, a few clouds and cooler air is slated to move in today. The decrease in temperature will limit wet avalanche activity on south facing slopes and avalanche danger has dropped to Normal Caution (LOW danger). Over the past week, avalanche activity has been related to afternoon warming on southerly facing slopes. This triggered a number of wet loose slides, a few moist slabs and a few glide avalanches. As the southerly slopes now sport a solid sun crust, which may not soften today, and wet avalanches are not expected, glide avalanches are the exception moving forward. Things to keep in mind if you are headed out today:

Glide avalanches – Several small glide cracks released yesterday. These types of avalanches are highly destructive, unpredictable and not associated with human triggers. It’s always best to watch for and limit exposure under glide cracks.
Dry-loose sluffs – Loose surface snow exists in steep shaded terrain. Dry sluffs can move faster than expected or knock a person over.
Cornice falls – As always in mountain travel, give cornices a wide berth.
An outlier slab avalanche – Although it is unlikely a person could trigger a slab avalanche, the mountains can harbor surprises, especially in thin snowpack areas. Considering the consequences before entering into high consequence terrain and maintaining good travel protocol are good habits that could pay off one day.

Glide avalanches on the lower portion of Raggedtop Mtn, releasing yesterday (3/1). Photo taken from Girdwood.

Recent wet loose avalanche activity in upper Glacier Creek / Girdwood Valley.

Additional Concern

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

South of Turnagain – Summit Lake and Silvertip zones: For anyone traveling in this area note that a shallow snowpack with a generally poor structure exists. A variety of old weak layers (facets and buried surface hoar) sit in the mid and base of the snowpack. It is uncertain as to how reactive these layers are at this point and if they could produce a slab avalanche. We do know whumpfing has been observed in the Summit area and last Thursday’s (2/21) wind event triggered many large slab avalanches breaking in deeper weak layers. Assessing the slab as well as the weak layer will be important. Old wind slabs in steep terrain sitting on weak snow are the most suspect places to trigger an avalanche.

Weather

Sat, March 2nd, 2019

Yesterday: Sunny skies with light and variable winds were over the region. Temperatures climbed into the mid 30’sF along the high peaks and mid elevations, while valley bottoms reached 30F. Overnight, temperatures have only dropped to the teens at most low elevations while ridgetop temperatures have dropped to the teens as well – limiting the inversion.

Today: A few clouds are slated to move in today along with a chance for valley fog. The ridge of high pressure is weaker and that has decreased temperatures in the Alpine and increased them at sea level. Daytime highs should reach the mid 20’sF along ridgelines and the mid 30’sF in the low elevations. Ridgetop winds will be light from the east, 5-10mph.

Tomorrow: Mostly cloudy skies with a chance for a snow flurry or two will be over the area. No accumulation is expected. Mountian temperatures look to remain in the teens to 20’sF while ridgetop winds will be light from the east.

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

	Temp Avg (F)	Snow (in)	Water (in)	Snow Depth (in)
Center Ridge (1880′)	29	0	0	59
Summit Lake (1400′)	21	0	0	28
Alyeska Mid (1700′)	30	0	0	54

RIDGETOP 24-hour data (6am – 6am)

	Temp Avg (F)	Wind Dir	Wind Avg (mph)	Wind Gust (mph)
Sunburst (3812′)	30	E	3	10
Seattle Ridge (2400′)	30	E	5	12

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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