Issued: Tue, Apr 03, 2018 at 8AM

Expires: Thu, Apr 05, 2018

Above 2,500ft Low

1,500 to 2,500ft Low

Below 1,500ft Low

Degrees of Avalanche Danger ?

1. Low
2. Moderate
3. Considerable
4. High
5. Extreme

Avalanche Danger Rose ?

Avalanche Problems ?

Problem Details

The avalanche danger is generally low, but with pockets of thin wind slab to watch out for. Remember, low danger does NOT mean no danger. Keep your eyes open and be on the lookout for any surprises.

Problem #1: Wind Slab

Location: Wind loaded E-S-W aspects, treeline and higher. 2-3″ of new snow that fell last week has been whipped around by Northerly winds. In isolated wind loaded areas, this new snow has formed fresh wind slabs up to 8″ thick. Keep an eye out for wind loaded slopes where these fresh surface slabs may be thick enough to sweep a person down into high-consequence terrain. These wind loaded pockets may cause small areas of MODERATE danger.

Fresh soft slab sensitive to human weight. Mt. Ripinsky, Thursday March 29th.

Problem #2: Deep Slab

Location: Thin areas above 2,500ft. Especially at the Chilkat Pass. Confidence: Low. Now that the midpack is solidly re-frozen, a strong bridge exists over the main weak layer (old facets 1m deep in the Lutak zone and 30-45cm deep in the Pass). In most areas, it will be nearly impossible to penetrate the upper frozen ice layer. BUT, in areas where the snowpack is thin, it may still be possible to trigger basal facets or depth hoar which could propagate into areas of deep slab. The likelihood of this happening is generally low, but still possible. Use extra caution to avoid thin rocky areas at the margins of a slab. Be careful when approaching summits, ridges, and other windswept areas. Unsupported slopes will be most likely to slide in this scenario.

Recent Avalanche Activity

During the freeze-thaw conditions over the weekend (March 17th-18th), reports from the field included one human-triggered wet slide at the Pass, and isolated whumphing/collapsing still happening in all zones.

There was a widespread avalanche cycle (March 10th-13th), mostly size D2-D3, a few D4, all aspects. Failure planes appear to have been both above and below the Jan. ice crust, within storm snow, and on depth hoar at the ground in some rocky areas.

Recent Weather

Temperatures have dropped several degrees the last few days, and even south aspects are staying solidly frozen through the day. Cold weather with moderate north winds will continue through Thursday. It should be mostly sunny with clouds increasing Thursday evening. 

 Snow Depth [in] Last 24-hr Snow/SWE [in] Last 3-days Snow/SWE [in]  Today’s Freezing Level [ft]  Today’s Winds Next 24-hr Snow/SWE
Mount Ripinsky @ treeline
59″ 0″ / 0.00 0″ / 0.00 0  mod, N 0″/ 0.00 *
Flower Mountain @ treeline
 44″ 0″ / 0.00 0″ / 0.00 0 light, NW 0″/ 0.00*
Chilkat Pass @ 3,500ft
 22″* 0″ / 0.00 * 0″ / 0.00* 0 mod, NW 0″/ 0.00 *

( *star means meteorological estimate )

Additional Info & Media

If you get out on the snow, send in your observations!

Posted in Transitional Zone Forecasts.
Erik Stevens

Forecaster: Erik Stevens