Haines Avalanche Center

Forecast Expired - 04/30/2021

Above 2,500ftConsiderable

1,500 to 2,500ftConsiderable

Below 1,500ftModerate

Degrees of Avalanche Danger

Avalanche Problems

Problem 1

Wet Avalanches:

Confidence: High.     Distribution: Scattered on solar aspects, isolated on shaded aspects.   Sensitivity: Reactive.

 

Below 4,000ft: Yesterday’s rainfall will have saturated the snowpack, causing natural wet slides in steep areas (especially north aspects). With decreased rainfall today, natural activity should begin to settle down, but human triggered slides remain likely. Keep in mind that temperatures will remain elevated and we haven’t had a solid freeze at these elevations since Wednesday. 

 

Above 4,000ft: Fresh storm snow will be poorly bonded and reactive, especially if the sun comes out and warms it up. You may find storm slab concerns that later turn into wet-slab concerns depending on aspect and temperature. If the sun comes out, expect the new snow to become active either way.

 

After today’s storm clears out, we will be getting back into a pattern of daily freeze/thaw cycles, which is good for our snowpack, but can lead to dangerous conditions when it’s hot out. If you’re out in the early morning, the slopes are likely to be frozen and stable. But as the temperature climbs in the afternoon, the danger will rapidly rise — especially on E-S-W aspects. Natural and Human-caused wet slides are likely during daytime heating on solar aspects steeper than 30 degrees. Some of these slides could be deep and destructive. As the spring progresses and temperatures warm again, North aspects may get into the action and begin a large wet slide cycle.

 

Our remaining snowpack still contains several rain/sun crusts, and a few old weak layers that will continue to weaken as the snowpack becomes warmer, softer, and wetter. Solar heating will cause water to percolate through the snowpack and run along crusts, which lubricates the layer.

 

  • If you travel in the mountains, do so in the early morning, before the snowpack heats up. When the snow softens to ankle-deep, it’s time to move to safer slopes.
  • Keep an eye on the weather stations. If we do not get a solid freeze overnight, expect increased wet slide activity and high danger the next morning.
  • Rocky areas will be common places for wet slides to be triggered.
  • Even small wet slides can easily entrain a person and carry them into a terrain trap.

 

 

Likelihood:

  • Almost Certain
  • Very Likely
  • Likely
  • Possible
  • Unlikely

Size:

  • Historic
  • Very Large
  • Large
  • Small

Trend

  • Increasing
  • Steady
  • Decreasing

Avalanche Activity

This D3 wet slab occurred 4/19 at 2pm. Transitional zone, Takhin ridge, (E aspect at 2800ft) Photo: Erik Stevens.

 

We had a major wet slide cycle 4/16 – 4/20 under record high temperatures. Things have cooled off drastically since then, but south aspects are still getting cooked.

Weather

Thursday brought rain up to 4000ft, and heavy snow above that level. Today the precip will diminish and temperatures will cool slightly. After the storm clears out, we should return to getting solid overnight freezes in the mountains, with daytime temperatures reaching the mid 30’s during the day above 4000ft. Clouds should start to break up Saturday afternoon, leading a nice day Sunday. The pattern looks generally cool and moist after that.

 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   120″+*  0″ / 1.00* 0″ / 1.00*   3500′  light, SE 0″ / 0.20*
Flower Mountain @ treeline  92″  0″ / 0.50* 0″ / 0.50*  3500′  light, SE 0″ / 0.10*
Chilkat Pass @ 3,100ft  46″  0″ / 0.20 0″ / 0.20*  3500′  light, SE 0″ / 0.10*

( *star means meteorological estimate )

—The Mt. Ripinsky weather station is completely buried and no longer reporting. We will try to get it dug out and back online within the next few months—

Additional Information

Practice like you play. Make sure all your rescue gear is fully functional and your beacon has full batteries. Make sure 1) everyone in the group has a functioning beacon, shovel and probe 2) knows how to use them and 3) has trained in companion rescue in the last year. Keep your skills fresh. If you head into the hills, watch out for red flag avalanche conditions, natural avalanches, whoomphing or collapsing, and shooting cracks.

 

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This will be our last update of the season. Click the + Full Forecast link below for each zone to read more. Thanks to all of our supporters, contributors, and sponsors for a great season!