Monday December 7, 2020

Wednesday December 9, 2020
Tuesday December 8, 2020
Monday December 7, 2020
Confidence: High - High precipitation amounts and warm temperatures = low stability and high certainty of hazardous conditions. Confidence decreases as this forecast period matures, as timing for cooling and stabilization is uncertain.

Main Concerns

Loose Wet, Storm Slab - view Avalanche Problems for detailed information.

Travel & Terrain Advice

Travel in avalanche terrain during periods of high hazard is not recommended.

Expect very warm temperatures and heavy rainfall to unconsolidated the snowpack. Even a small amount of loose wet snow that is available for entrainment can cause a small slide to gain enough mass to push a mountain traveler into or over a terrain trap.

Snow depths throughout the island mountains range from 30 to 60 cm and 100 cm plus above the 1500 meter mark. Early season conditions exist. Stay alert for open creeks, tree wells, crevasses, or other exposed hazards

Avalanche Summary

No New Avalanches have been observed or reported during the past forecast period.

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Avalanche Problems

Loose Wet

This problem will become wide spread as freezing levels remain high and precipitation in the form of rain becomes intense. During Monday and Tuesday Expect this problem to remain very touchy to human triggering. Overhead hazard may run into below tree line terrain, otherwise the snowpack is very low at the lower elevations and may not have enough mass to pose a hazard.

Location: Found in the Alpine and Tree line, may effect below tree line terrain.

Possibility: Triggering of this avalanche problem is very likely to certain from light loads such as skiers. Natural avalanches are likely to very likely.

Size: If triggered expect these avalanches to be small, but will have the potential to gain mass and become large size 2 and in isolated terrain become very large .

Storm Slab

The storm slab problem will initially begin to develop in the alpine as freezing levels will begin to drop and precipitation will fall as snow. The snowfall will come in warm and leave cold and this may promote a bond to the old surface. Expect storms slabs to be touchy and may be deep up to 50cm dependent on when the rain turns to snow.

Location: Found in the Alpine and Tree line

Possibility: Triggering of this avalanche problem is likely from light loads such as skiers. Natural avalanches are possible.

Size: If triggered expect these avalanches to be large size 2 and in isolated terrain become very large .

Snowpack Summary

The past forecast period has seen the snowpack continue to shrink from the tree line elevation and down. The entire snowpack at lower elevation is moist to wet with the upper 30cm becoming unconsolidated and presenting as isothermal. The past warming has continued to promote melt and settlement with many areas at tree line becoming disconnected and below tree line most areas with any inclination have become disconnected. Alpine snowpack has remained intact and reports indicate that it continues to recover or refreeze during period of cooling, providing a melt freeze crust that is supportive on north aspects.

Snowpack Details

SurfaceSurfaces moist to wet with upper ALP north aspects a supportive melt freeze crust
UpperUnconsolidated and moist with Alpine north aspects consolidated.
MidSettle, Below the treeline elevation unconsolidated.
LowerWell settled and dense.

Past Weather

Unsettled conditions prevailed over the past forecast period, with mainly warm temperatures, clear sky and occasional clouds with some light precipitation.

Weather Forecast

A series of pacific storms will begin to enter the forecast region, bringing heavy precipitation amounts, strong winds (values exceeding 100km/hr at ridge top) and high temperatures and freezing levels. Beginning early Wednesday, freezing levels and temperatures are forecast to begin to drop. Precipitation amount on western side of the island range may see values from 100 to 130mm.

Monday: 30-50 mm, Winds Strong from the South West, Freezing levels to 2800 m Temps @1500m +5c.

Tuesday: 50-60mm, Winds Strong from the South West, Freezing levels to 1100 m Temps @1500m +2c.

Wednesday: Trace , Winds Moderate from the South West, Freezing levels 1000 m Temps @1500m -1.

Posted on Monday December 7, 2020 by Jesse Percival

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