Bollettino valanghe

South Rockies

Mar 17 – 18, 2017Avalanche Canada
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Archiviato · scaduto 10 years ago

Pericolo valanghe

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

In sintesi

Saturday's weather will test the snowpack and a natural avalanche cycle is expected to occur. Northern parts of the region may see conditions similar to adjacent regions where danger has been rated Extreme.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Very Likely
    Dimensione
    1–2
    New snow will combine with intense winds to form touchy new wind slabs at high elevations on Saturday. Rain may fall as high as 1800 metres and promote loose wet avalanches. Both problems have the potential to trigger deep slabs.

  • Deep Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible - Likely
    Dimensione
    2–4
    The lack of an overnight refreeze will make the impact of Saturday's 2200m freezing levels even stronger. Warming aside, new snow, wind, and rain are set to provide ample natural triggers for deep persistent slabs.

Confidence

Moderate -

Weather Forecast

Saturday: Flurries bringing 10-20 cm of new snow to higher elevations with a possibility of localized enhanced amounts. Rain below about 1800 metres. Strong to extreme southwest winds. Freezing level to 2200 metres with alpine temperatures of 0 to +1. Sunday: Sunny with cloudy periods. Moderate west winds. Freezing level to 1400 metres with alpine temperatures around -9. Monday: A mix of sun and cloud. Light southeast winds. Freezing level to 1700 metres with alpine temperatures of -6.

Avalanche Summary

A report from the Crowsnest area showed a natural Size 3.5 deep persistent slab that began as a ridgetop wind slab release before stepping down to ground as it descended its track. Looking forward, another dose of wind and snow will see wind slabs continue to develop in the alpine above the high freezing levels while rain soaks the snowpack again at lower elevations. The potential for deep persistent avalanches is very real concern for Saturday.

Snowpack Summary

An unexpected 15 cm of new snow fell over the south of the region on Thursday night, with a trace to 5 cm accumulating in most of the region. Below the new snow, recent warm, wet, and windy weather has formed fresh wind slabs at higher elevations while saturating the snowpack with rain below treeline. The rain soaked snow has refrozen into a crust that may be supportive at higher elevations. Regular snowfall throughout early March has seen roughly 50-90 cm of snow accumulate above the crust and facet interfaces from February. In some areas this storm snow may have a poor bond to these interfaces. Aside from that uncertainty, the mid-pack in the region is generally strong. With that said, the bottom third of the snowpack is composed of weak sugary facets roughly 1-1.5 metres deep. The potential for full-depth avalanches over this basal weakness remains a real concern, especially as ongoing loading and warming continue to stress the snowpack.

Regioni coperte