Wednesday April 4, 2018
Cornice Fall, Wet Slab, Persistent Slab
Travel & Terrain Advice
Avoid avalanche terrain when rapid warming and rain on snow events are forecast.
Give a wide berth when travelling either above or below cornices.
No new natural avalanches have been observed and ski testing has not produced any significant results in the past 48 hours.
New snow followed by warming temperatures will first build cornice tabs and will then become fragile and sensitive to human triggering. If trigger these hazardous features could when failing and falling onto the slopes below , then trigger either a wet slab or persistent slab.Found at ridge tops in both the alpine and at treeline these hazardous features will become very susceptible to triggering from light triggers such as mountain travelers and when triggered will be large to very large in size.
New snow followed by rainfall will create this new and hazardous feature. Expect to find this slab problem on all aspects and elevations and during times of rapid warming and rain fall to be touchy to very touchy to human triggers. If triggered a slab avalanche may be very large in size and potentially very destructive.
New snow and continued loading in the form of rain, may trigger this established and persistent problem found down between 10 and 50 cm. This hazardous problem can be found on all aspects in both the alpine and tree line. During the warming and loading cycle of the coming storm, expect these avalanche problems to become more sensitive to triggering as the load builds during the forecast warming storm cycle and if triggered will be large to very large in size
A strengthening melt freeze crust has developed over the last 72 hours and continues to build strength as temps have remained low and today very little solar effect was present. The surface melt freeze crust dominates the upper snow pack and can be found on all aspects and at elevations up to 1700 meters. The March 22 melt freeze crust can be found down from 15 to 45 cm and is producing hard resistant planar results when tested. Mid and lower snow pack is well settled and dense.
|Surface||well established melt feeze crust|
|Upper||a melt freeze crust buried down between 10 and 50 cm|
An arctic high pressure to the north of the region has brought to the forecast area below seasonal temperatures with light snow fall and light south west wind. Freezing levels have fluctuated between near seas level overnight and 1200 meters by mid day.
A westerly flow will enter the region late Wednesday bringing to the forecast area, rising freezing levels and temperatures, moderate precipitation amounts and moderate to strong south east wind. Western zones will receive substantially more precipitation and warmer temperatures with inland and eastern zones slightly cooler with less wind and precipitation.
Wednesday 0 to 5 cm new snowfall temps -1 to 3, winds light south east, freezing level 600 m rising to 1200 m mid day.
Thursday 10 to 20 cm of snowfall followed by 5-15 mm of rainfall late afternoon temps 0 rising to +3.5, winds moderate south east, freezing level 1000 m rising to 1700 m near days end.
Friday 10 to 30 mm of rainfall temps +3 to +6 winds moderate south east , freezing level 1700 m rising to 1800 m mid day.
Posted on Wednesday April 4, 2018 by Jesse Percival