Friday February 8, 2019

Sunday February 10, 2019
Saturday February 9, 2019
Friday February 8, 2019
Confidence: High - Good degree of confidence with Weather models in agreement. North Island will see sustained strong winds throughout much of the weekend.

Main Concerns

Wind Slab, Loose Dry - view Avalanche Problems for detailed information.

Travel & Terrain Advice

Exercise caution if you are choosing to travel at treeline and Alpine elevation bands this weekend. Southerly Aspects will receive a substantial amount of wind driven snow load and create wind slabs. Given the wind speeds forecasted for Friday and Saturday, size 2 avalanches could likely be initiated on terrain below ridges, in depressions and at mountaintop below cornices. Keep your eyes peeled for cornice development in an atypical (reverse loading) format and expect south aspects to produce avalanches. Beware of snow cracking underfoot or under your snowmobile and take this as a clear indication of unstable snow. Find supportive and well anchored terrain in the trees, away from open wind exposed slopes. If you are travelling at higher elevation bands, cautious route finding and careful decision making and terrain selection will make for a successful outing.

Avalanche Summary

A relatively calm period of weather and lower avalanche hazard will shift on Friday February 8th as moderate winds will begin to move snow from North slopes onto southerly aspects. Saturday’s strong forecasted winds could create wind slabs up to size 2+ on southerly aspects. This trend of wind slabs will continue foir the duration of the weekend as strong winds will persist throughout Saturday. In wind protected areas, loose unconsolidated ‘sloughs’ (size 1) can be initiated on steep unsupported terrain.

Avalanche Problems

Wind Slab

Moderate snow transport begins Friday February 8th. More substantial snow transport will begin Saturday on the North end of the Island around Mt Cain where strong sustained winds are predicted throughout much of Saturday. Given the approximate 30+cm of light dry powder snow currently available for transport, we could expect likely triggering of avalanches (size 2+) on southerly aspects where wind slabs will linger throughout the weekend.

Loose Dry

Loose dry ‘sloughs’ could pose a threat to recreational users travelling on steep unsupported terrain. There is currently 30 cm of unconsolidated snow that sits atop a firm melt freeze crust. Expect ‘sloughing’ and small size 1 avalanches as a result of this unconsolidated snow on steep unsupported terrain.

Snowpack Summary

The snowpack is extremely well bonded. There remains 10 - 30 cm of light dry powder snow sitting on a very consolidated snowpack that is composed of a number of melt freeze and ice crusts. If the cold temperatures continue to persist, we may begin to see surface faceting due to these cold temperatures. However at this time the snowpack remains very well bonded.

Snowpack Details

Surface10cm - 30 cm of light, fluffy dry snow and is bonding poorly to crust below
Upperthick 10cm melt freeze crust at treeline and a 3cm thick melt freeze crust above treeline
MidWell bonded mid-pack that does include two weaker (PWL) layers that are currently un-reactive (Facet layer and Surface hoar layer)
LowerWell Settled

Past Weather

Cold temperatures and clear weather has persisted throughout the week.

Weather Forecast

Friday: 3 to 5 cm of new snow, Temperature -1 to -17 degrees, Strong Winds from the North beginning late morning, Freezing Level 300M

Saturday: no new snow, Temperature -8 to -21 degrees, Strong to moderate Winds from the North, Freezing Level 0M

Sunday: no new snow, Temperature -5 to -17, Light to Moderate Winds from the North, Freezing Level 0M

Posted on Friday February 8, 2019 by Ryan Shelly

Past Bulletins