Bollettino valanghe

Northwest Coastal

Apr 4 – 5, 2014Avalanche Canada
Vedi sulla mappa
Archiviato · scaduto 12 years ago

Pericolo valanghe

Sun
Mon
Alta quota
4 · Forte
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
Apri la mappa completa

In sintesi

Storms for Saturday and Monday are being focussed on this region. If current weather models hold, things could turn very ugly on Monday.

Problemi valanghivi

  • Storm Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Very Likely
    Dimensione
    1–5
    New snow driven by strong ridge top winds has likely created touchy slabs at and above treeline. This snow adds to existing storm snow and is expected to be unstable on steep lee features.

  • Deep Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely - Possible
    Dimensione
    3–7
    Two buried weak layers exist in the snowpack. These weak layers could be activated by cornice fall, a smaller surface avalanche in motion, or a rider finding the sweet spot, which would be most likely in steep rocky terrain.

Confidence

Fair - Intensity of incoming weather systems is uncertain

Weather Forecast

Friday night: 5-10 cm expected overnight. Saturday: 15-20 cm new snow expected with freezing levels around 600 m. Strong winds, 50-60 km/h from the SW. Sunday: Scattered showers in the morning. Freezing levels around 600 m. Winds 30-40 km/h from the NW. Monday: Very heavy precipitation. Current models are showing as much as 80 mm for Terrace with 80-100km/h winds and freezing levels rising to 1500 m. If current models hold this could be a very significant weather event.

Avalanche Summary

On Thursday, a size 2.5 loose wet avalanche was reported from Bear Pass that occurred in response to rain that fell to 1100 m. Otherwise we did not have any activity reportedOn Tuesday there was one report of a remotely triggered size 2 wind slab avalanche on a NE facing aspect at 1500m. This location had previously slid on the early February crust/facet/surface hoar combo. Isolated loose wet avalanches to size 1.5 were also reported from steep southerly terrain.On Monday a large rock fall event initiated a size 3.5 avalanche that failed on the early February persistent weak layer. Several smaller loose snow avalanches to size 2 were running in the recent storm snow on steep solar aspects too.

Snowpack Summary

15 - 25cm new snow fell on Thursday onto a mix of surface hoar, small grained facets and melt freeze crusts.Previous to Thursday's snow, it was starting to feel like spring in the NW. Valley temps have been creeping into the double digits during the day, and there were reports of the top 15 cm of the snowpack regularly becoming moist with daytime heating. Previous snow that fell between March 27th to 30th fell on on top of a haggard old surface composed of old wind slab, melt freeze crust, and faceted old snow. I suspect the ongoing melt freeze cycles have largely healed any instabilities associated with this interface.The early March layer can be found down 75 - 100cm and is composed of facets/surface hoar on shady aspects and facets/crust on southerly aspects. The early February crust/facet/surface hoar combo is down 150 - 200cm. This layer was responsible for a couple of unexpected large avalanches right at the end of March and the beginning of April. I would not rule out the possibility of this layer re-awakening if and when we get a prolonged period of warming and/or intense solar radiation.

Regioni coperte