Avalanche Forecast
Issued: Mar 5th, 2021 1:00AM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Storm Slabs.
Jesse Percival,
VIAC
Thursday afternoon avalanche control teams at Mount Washington report at 1500 metes on North aspect, ski cutting touchy fresh wind slab up to 50cm in depth, size 1. Reports of numerous skier accidental avalanches with no back ground information have been submitted. Overall touchy avalanche conditions exist as rapidly loading new snow is and will continue to build touchy storm and wind slab.
Summary
Past Weather
Thursday night into Friday morning up to 30 centimeters of new snow fell above 1000-1200 m below this elevation precipitation was in the form of rain. Winds where strong, exceeding 60km/hr out of the South East.
Weather Forecast
A series of Pacific storm fronts in the region are forecast to continue to bring to the area heavy snowfall amounts and strong South East wind. Expect freezing levels fluctuation as both cold and warm fronts pass the area and precipitation will fall as predominantly snow, but in zones south of Arrowsmith, intermittent rain is more likely to occur, all dependent on freezing levels and timing. Friday: 30 to 60 cm of snow. Winds Strong from the Southeast, Freezing levels 1200 meters high descending to 700 meters.Saturday: 15 to 20cm of snow, Winds Moderate to Strong from the South East , Freezing level 900 meter high descending to 600 meters.Sunday: 5 to 15cm. Winds Moderate from the South East, Freezing levels 600 to 700 meters.
Terrain Advice
**Avoidance of avalanche terrain during periods of high avalanche hazard is recommended.** Very careful route finding, seeking non avalanche terrain is crucial as a period of high instability and hazard will be in full effect.
Snowpack Summary
New snowfall delivered with strong winds overlies a well developed surface crust on south aspects and a variety of surfaces on north aspects. In many places the new snow is bonding poorly to old surfaces. New Wind slabs have been forming rapidly beginning Thursday afternoon on North aspects with depths reaching 50 cm's.The newly developing instability will continue to grow in depth and destructive size, patience and time is needed for this new instability to settle out. The mid and lower snowpack is well settle and dense. Snowpack heights throughout the island forecast area range from 300 to 500 centimeters.
Snowpack Details
- Surface: New snow and wind affected snow deposited on north aspects, soured and pressed areas on south aspects.
- Upper: South aspects a crsut exisits that and on north aspects old windslabs and some preseved snow can be found.
- Mid: Old unreactive crusts, overall dense and well settled.
- Lower: Well settled and dense.
Confidence
High - Certainty with weather forecasts models for heavy precipitation amounts and wind provides a strong mental model of expected snowpack conditions and avalanche hazard and problems for the coming forecast period.
Problems
Wind Slabs
This problem will continue to grow in destructive size and remain touchy to light triggers as continued new storm snow and wind is forecast throughout this forecast period.
**Location:** Specific to North aspects in areas lee of ridgetops, expect cross loading of gulley features and areas at convex rolls with in terrain continue to build wind slab throughout the forecast period.
**Possibility:** Triggering of this avalanche problem from light loads such as skiers is very likely to certain Natural avalanches are very likely to certain.
**Size:** If triggered, expect these avalanches to be specific to terrain on Northwest thru to North east and be large size 2, in isolated terrain features very large up to size 3. Potential over this forecast period for avalanches to exceed size three is possible.
Likelihood
Expected Size
Storm Slabs
Storm slabs will build over the this forecast period as temperatures fluctuate and heavy snowfall occurs.
**Location:** Widespread in areas not scoured and stripped by the wind. Expect depths of new snow during the forecast period to exceed 60 centimeters and this will promote the formation of a new and touchy storm slab.
**Possibility:**Triggering of this avalanche problem from light loads such as skiers is very likely to certain Natural avalanches are very likely to certain.
**Size:** If triggered, expect these avalanches to be large size 2, in isolated terrain features very large up to size 3.
Likelihood
Expected Size
Valid until: Mar 6th, 2021 1:00AM
