Sun, April 26, 2015 Turnagain Pass Avalanche Forecast

Sun, April 26th, 2015

Alpine

Above 2,500'

2 - Moderate

Treeline

1,000'-2,500'

2 - Moderate

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

After several days of mostly clear skies and a springtime melt-freeze regime, we have very warm temperatures and cloud cover that has moved in overnight. Ridgetop temperatures are reading between 30 and 32F this morning and cloud cover has likely limited the amount of surface re-freeze. What this means is an increase in wet avalanche potential as daytime warming does not have to soften surface crusts before destabilizing the snowpack. This also is how our springtime “shed cycle” begins; the shed cycle is when we see large natural wet avalanches as the snowpack melts away and sluffs off the mountainsides. Will this week’s warming initiate a true shed cycle? It’s too soon to say, but we need to keep the idea in mind as there is still plenty of snow at the higher elevations that has yet to transition into a summer snowpack. Watching for recent wet avalanche activity throughout the next several weeks should be on our minds.

WET LOOSE AVALANCHES:
If you are headed out today, paying attention to the amount of overnight re-freeze on Southerly aspects will be key. If the snow is unsupportable and saturated – stay off of steep slopes as large wet loose avalanches are possible. On Northerly aspects, watch for the soft settled powder to become damp, or even wet. If this occurs, damp and wet sluffs will be possible on steep Northerly slopes.

CORNICES:
Cornices could start calving with the warm temperatures this week. As always, steering clear of these from both above and below is wise. Cornice crevasses are also showing up along ridgelines; this is where the cornice pulls away from the underlying terrain or snow.

Photo below is of a cornice crevasse from the CFR ridge on Tincan this weekend.

Weather

Sun, April 26th, 2015

Yesterday was yet another inviting and mostly sunny day in the backcountry. Ridgetop winds were light from the East and temperatures warm, near 30F on the ridgelines and mid 40’s F at 1,000′.

Today, we have cloud cover and very WARM air being ushered in as large low pressure system spins in the Gulf. We are too far North of the system for precipitation but we should see overcast skies and season high temperatures in the 34-38F range on the ridgelines. Ridgetop winds are expected to be light to moderate, 10-20mph, from the North and East.

For Monday, intermittent cloud cover, warm temperatures and light precipitation is expected. Accumulations look to be only 1-3″ at the upper elevations with a rain/snow line ~1,500′. Ridgetop winds are expected to be from the North as West as the low-pressure in the Gulf moves off to the Southeast and a wrap-around flow pattern sets up.

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

	Temp Avg (F)	Snow (in)	Water (in)	Snow Depth (in)
Center Ridge (1880′)	41	0	0	70
Summit Lake (1400′)	40	0	0	13
Alyeska Mid (1700′)	42	0	0	43

RIDGETOP 24-hour data (6am – 6am)

	Temp Avg (F)	Wind Dir	Wind Avg (mph)	Wind Gust (mph)
Sunburst (3812′)	28	E	11	34
Seattle Ridge (2400′)	32	n/a	11	29

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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