Issued: Wed, Mar 21, 2018 at 8AM

Expires: Fri, Mar 23, 2018

Above 2,500ft Considerable

1,500 to 2,500ft Considerable

Below 1,500ft Moderate

Degrees of Avalanche Danger ?

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

Avalanche Danger Rose ?

Avalanche Problems ?

Problem Details

Problem #1: Wind Slab

Tuesday’s storm somehow lined up right over Mt. Ripinksy, with a quick 19″ of wet snow falling. Winds were light, but are now increasing out of the north. These north winds will continue the next few days, causing heavy wind loading on lee aspects. Human triggered avalanches will be likely within the new storm snow and fresh wind slabs that form on top.

Problem #2: Deep Slab

Location: All aspects above 1500ft. Confidence: Low Now that the snowpack is re-freezing solidly, a strong bridge is forming over the main weak layer (old facets 1m deep in the Lutak zone and 30-45cm deep in the Pass). The snowpack was isothermal (0 degrees C) last week through the upper 60cm, but has now dropped below freezing. 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

19″ of wet snow fell in the Lutak zone mountains Tuesday. Temperatures will be dropping well below freezing this week as moderate-strong north winds come in. Clouds will probably stick around through Thursday before clearing up, though there may be some breaks.

 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
68″ 19″ / 1.50 19″ / 1.50 0  mod, N 0″/ 0.00 *
Flower Mountain @ treeline
 46″ 2″ / 0.20 2″ / 0.20 0 light, NW 0″/ 0.00*
Chilkat Pass @ 3,500ft
 27″* 2″ / 0.20 * 2″ / 0.20 * 0 light, 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