Fri, April 25, 2014 Turnagain Pass Avalanche Forecast

Fri, April 25th, 2014

Alpine

Above 2,500'

2 - Moderate

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

Wind Slabs

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

More info at Avalanche.org

After a long stretch of clear skies, sunscreen and quiet avalanche conditions, we are getting back into a somewhat stormy weather pattern. The Easterly winds already picked up along the ridgelines yesterday and there is snow above 1500ft on tap for the next several days.

As we head back into winter at the upper elevations we can put loose snow sluffs and wind slabs back on our radar. Snow is expected to fall in earnest this afternoon and although amounts are uncertain, as is often the case, we could see up to 4” by sunset (~9:45pm). Favored areas such as Portage Valley could see 5-7”. This will be falling on old stout surface crusts.

Wind slab avalanches should be expected on any slope with recent wind deposited snow. Considering there is very little pre-existing snow available to transport, it will depend on new snow amounts as to wind slab formation and size. With modest amounts expected the avalanche activity should be fairly low in volume, predictable and easy to suss out.

A look at the pre-existing surface from the Sunburst parking A look at this morning’s weather conditions (Tincan Ridge from
lot yesterday. the DOT Turnagain Pass webcams).

Weather

Fri, April 25th, 2014

Yesterday was another bluebird day on the Pass. Sunny skies gave way to a few cumulus clouds by the afternoon and temperatures climbed to the mid 30’s F on the peaks. The wind kicked up to the 20mph range from the East late in the day and has continued overnight associated with a small system moving through from the Gulf.

Today this smaller system continues to move North ahead of a large Aleutian Low tracking East with an associated front which will impact our region by the afternoon. There is a chance for .4 € of rain below 1500ft with 2-4 € of snow above from this afternoon through midnight. Winds will continue from the East in the 25-35mph range and temperatures look to stay in the mid 20’s F above treeline and 35-40F at 1000ft.

The front mentioned above is forecast to stall out over us for the weekend with 40-50mph Easterly winds and a decent shot of rain/snow can be expected (the rain/snow line should be around 1200ft). As for the CORN HARVEST tomorrow from 3-7pm €“ let’s hope we get a little break in the cloud cover and precipitation!

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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