Hatcher Pass Avalanche Center

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ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Thu, April 11th, 2019 - 7:00AM
Expires
Fri, April 12th, 2019 - 7:00AM
Forecaster
HPAC Staff
Conditions Summary

This information is a Conditions Update. Danger ratings are only issued with avalanches advisories.  The next avalanche advisory is scheduled for Saturday April 13, 2019.

MIDWEEK SNOW AND AVALANCHE CONDITIONS SUMMARY FOR APRIL 11, 2019

Natural and human-triggered avalanches will be unlikely today. While generally safe avalanche conditions exist, watch for unstable snow on isolated or extreme terrain features. However, if the sun pops out and temperatures rise, isolated small wet loose and wet slab avalanches may be possible on steep E to W aspects at  mid and upper elevations and all aspects at lower elevations.

Cornices are still large and unpredictable, give them a wide berth.

In surveys of Upper Willow Creek, Independence Mine Bowl, Archangel, Reed Lakes drainage this week, only one natural, large wet loose avalanche (possible wet slab) was observed. This avalanche occurred on a west aspect on Across Motherlode run at 4000’ and is believed to have occurred Tuesday. ~1.5” of new snow fell above 2000’ on Tuesday afternoon, with rain falling below 2000’.  Several very small wet loose point releases were observed on southerly aspects Tuesday afternoon.

All aspects at lower elevations and southerly aspects at mid and upper elevations are rapidly melting out with bare ground exposed across Hatcher Pass. Great corn harvesting is possible, with the right timing, on E to SW aspects.  6” deep near surface facets exist on due north aspects at upper elevations.  While most due north aspects at upper elevations have been heavily skied near the road, especially in Independence Mine Bowl, if you are willing to travel further out, excellent skiing and riding awaits on north aspects.

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Thu, April 11th, 2019
Recent Avalanches

The only avalanche observed this week was a natural, large wet loose avalanche (possible wet slab). This avalanche occurred on a west aspect on Across Motherlode run at 4000’ and is believed to have occurred Tuesday

Avalanche Problem 1
  • Cornice
    Cornice
Cornice
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.
More info at Avalanche.org

Cornices are large and can be difficult and dangerous to assess.  Cutting cornices of this size as a stability tool is not recommended nor effective.  We recommend avoiding traveling beneath them, especially during the warmest part of the day. Cornice fall can trigger large slab avalanches that run further than anticipated.  Choose safe zones out of the anticipated runout of potentially large avalanches. Cornices are unpredictable, it’s best to just avoid them.

Avalanche Problem 2
  • Wet Loose
    Wet Loose
Wet Loose
Wet Loose avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.
More info at Avalanche.org

While wet loose avalanche activity will generally be unlikely today, if the sun pops out and temperatures rise enough to melt surface crusts, isolated small to large wet loose avalanches may be possible on steep E to W aspects at mid and upper elevations and all aspects at lower elevations.  Fortunately, the snowpack gives us clues when the it becomes wet enough to be a problem. Rollerballs, wet soggy snow, and stepping into the snow and sinking in more than shin deep are red flags for when to move to shadier aspects and cooler terrain. Freezing nights and cooler daytime temps will keep wet avalanches to a minimum today.

Additional Concern
  • Wet Slab
    Wet Slab
Wet Slab
Wet Slab avalanches are the release of a cohesive layer of snow (a slab) that is generally moist or wet when the flow of liquid water weakens the bond between the slab and the surface below (snow or ground). They often occur during prolonged warming events and/or rain-on-snow events. Wet Slabs can be very unpredictable and destructive.
More info at Avalanche.org

Wet slabs will generally be unlikely at low elevation to the lack of a slab component.  Overnight freezing temps about 3000’ will also limit wet slab activity and mid and upper elevations, although small avalanches in isolated terrain are possible.

Weather
Thu, April 11th, 2019

Weather at 3450′ since Saturday 4/6:

Temperatures averaged 32°F, with a low of 24°F and a high of 42°F.

There has been ~1.5″ new snow recorded at Independence Mine.

Weather at 4500′ since Saturday 4/6:

Temperatures averaged  27°F, with a low of  22°F and a high of 39°F.

Winds averaged ESE-SSE 6 mph, max 17 mph.  Gusts averaged SSE 10 mph, max gust 26 mph.

Forecast Weather

Stay tuned to the NOAA point forecast for an updated weather forecast each day. The best way to see if it’s snowing in Hatcher Pass is to look at the webcam snow stake HERE and the Independence Mine SNOTEL site HERE

State Parks Snow Report and Motorized Access information can be found here.

Observations
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