Tue, April 01, 2014 Turnagain Pass Avalanche Forecast

Tue, April 1st, 2014

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

Cornice

Cornice

Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.

More info at Avalanche.org

We end Marvelous March and begin Amazing April with the 16th day in a row of sunny and beautiful weather. There are light and variable winds on tap and coupled with 13 hours 24 minutes of sunshine, we can expect some surface warming on slopes with a Southerly tilt. Many of these slopes have large looming cornices that will be baking in the sun again today. We have not seen many cornice falls recently but due to their unpredictable nature, they are good to avoid regardless. Additionally, as with all mountain travel in the spring-time, being aware of what is above you is essential, especially when daytime warming loosens the snow and rocks up.

Below is a photo Graham took yesterday of a corniced ridgeline near Bear Valley/Portage area. Graham also noted what looked to be a ‘semi’ fresh avalanche in the Bear Valley area – thought to be triggered by ice fall. See more on that and his write-up HERE.

Avalanche Problem 2

Dry Loose

Dry Loose

Dry Loose avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.

More info at Avalanche.org

Though some may think it’s a fool’s errand to be looking for powder right now, the fact is shaded areas continue to sport good riding conditions. Each day under these clear skies the surface continues to facet and become looser. On many shady slopes there is between 2 and 6″ of ‘re-cycled powder’, so to speak. If the slope is steep enough however, triggering low volume sluffs in this loose snow is fairly easy – it seems the slope has be over 40 degrees.

Southerly slopes are heating up just enough to soften for a few hours in the late afternoon, but hit these at the wrong time and it’s survival travel – at best. We have not heard of, or seen, any wet sluffs on these aspects recently. Yet, it is always something to keep in mind if you find yourself on a steep sunny slope with several inches of wet and sloppy snow.

‘Re-cycled’ or ‘Re-crystallized’ powder on Northerly aspects:

Weather

Tue, April 1st, 2014

During the past 24-hours skies have been clear and temperatures have averaged in the mid-20’sF at the higher elevations. Winds have been light from the West and North in the 5mph range and are dying off this morning.

For today, it should feel quite warm out there with the increasing sunshine. Ridge top winds are expected to be light and variable – even on the highest peaks. Temperatures that have cooled to the low teens at the valley bottoms should climb to the low 30’sF during the day while the ridge tops will remain in the mid-20’sF.

For tomorrow, another carbon copy sunny day. Yet, for the weekend the large scale pattern is shifting slightly. The blocking high over us currently looks like it might migrate East and put Southcentral a bit more in the line of fire for some precipitation (at the very least, cloud cover…). Stay tuned.

March Recap: In like a lamb, teased by a lion, then out like a lamb…

Well, March ended up being fairly uncomplicated weather wise. The Monthly weather chart says it all. After 9 days of clear and cold conditions Winter Part III arrived with a one week storm cycle that put down 5′ of heavy snow (5+” water). As one would expect, a healthy avalanche cycle ensued and then from March 17 to the 31st not a hint of precip was seen. There are many tan faces littering the mountains attesting to the last 15 days of bluebird weather!

Snowpack: As of April 1st we are at 52% of our median SWE (snow water equivalent).

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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