Issued: Sat, Apr 07, 2018 at 8AM

Expires: Sun, Apr 08, 2018

Above 2,500ft Moderate

1,500 to 2,500ft Considerable

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

As temperatures rise and the sun comes out today, wet slides will become possible on steep sunny slopes. We also have pockets of thin surface wind slab to watch out for. Keep your eyes open and be on the lookout for any surprises.  Temperatures are starting around freezing at 2,500ft, and will rise to 40-45F today.

Problem #1: Wet Avalanches

Location: Steep E-S-W aspects below 3,500ft. As temperatures rise above freezing through the day and the sun shines in force, sunny aspects will be taking on a lot of heat. Melting and softening will increase the danger of human-triggered wet slabs and large, dangerous wet sluffs as the day goes on. Restrict travel on these aspects to the early-morning hours when the snow is still frozen. If the snow softens to ankle-deep or more, it’s time to get off those steep sunny slopes.

Problem #2: 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 #3: 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

Clouds are expected to move in Friday, with some sunny breaks Saturday. Temperatures will be warming up slowly over the next few days, and north winds will decrease. Clouds and some light rain/snow are possible Sunday.

 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 3,000  mod, N 0″/ 0.00 *
Flower Mountain @ treeline
 44″ 0″ / 0.00 0″ / 0.00 3,000 light, NW 0″/ 0.00*
Chilkat Pass @ 3,500ft
 22″* 0″ / 0.00 * 0″ / 0.00* 3,000 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 Lutak Forecasts.
Erik Stevens

Forecaster: Erik Stevens