Monday February 10, 2020

Wednesday February 12, 2020
Tuesday February 11, 2020
Monday February 10, 2020
Confidence: High - Weather models in agreement and good field data.

Main Concerns

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

Travel & Terrain Advice

Continue to be wary of wind loaded features in the alpine and open treeline as wind slabs will be slow to bond to the crust below. Watch for warming at treeline and below treeline elevations on Monday as loose wet avalanches are a possibility. Avoid exposure to terrain traps during the thaw.

Avalanche Summary

Many reports of ski and sled accidental triggers of size 1 to 1.5 avalanches Saturday (after the Friday storm cycle). One size 1.5-2 accidental from Mt Cains East Bowl (no injury or lost gear) Numerous size 1-2.5 naturally triggered avalanches in the alpine and treeline elevation bands from steep cross loaded features, chutes and obvious start zones (most likely released during the storm Friday into saturday).

Avalanche Problems

Loose Wet

High freezing levels (2000 m) and warm temps midday Monday may result in loose wet avalanches up to size 1. These slides may possibly trigger naturally of rocky features and trees and will likely trigger with human activity. The storm snow from Fri/Sat has a easy sliding surface to move on with the crust below. Avoid steep loaded slopes in the treeline and below treeline and stay away from terrain traps during the warm up on all aspects.

Wind Slab

Strong winds from the SE and NW has moved the new snow from Fri/Sat to NW and SE aspects in the treeline and alpine and left behind a widespread wind slab issue. These slabs are sitting on the crust created after the huge monsoon rain event on Jan 31. The slabs have a poor to moderate bond to the crust below and will take time to gel together. There is a possible chance for these wind slabs to trigger naturally (most likely Monday with the warm up) and a likely chance of human triggering in both the treeline and alpine zones on NW to SE aspects. These wind slabs could produce avalanches from size one up to size 2.5.

Snowpack Summary

Variable surface conditions. Mainly storm snow over the Jan 31 crust.

Snowpack Details

Surfacethin crust at lower elevations, mid storm snow from Fri, upper pockets of wind blown snow scoured ridgetops
UpperStorm snow from Friday's event bonding moderate to poor to the rain crust from the Jan 31st monsoon rainfall
Midwell settled moist snow and numerous crusts
Lowerwell settled

Past Weather

10 to 25 cm of new snow fell Friday into Saturday morning with strong winds from the SE ending with NW. Winds flip-flopped back and forth from strong to mod SE to NW over the weekend transporting storm snow at upper elevations. Temps remained cool over the weekend until Sunday mid day when positive temps shot up to approx 1700 m.

Weather Forecast

Light amounts of precip over the next three days with temps hovering near or just below 0 degrees. Next half decent new snow arriving late Wed into early Thurs.

Monday - no new snow, winds moderate NW, temps 1 to 3 degrees, freezing level up to 2000 m mid day.

Tuesday - trace to 2 cm of new snow, winds strong SW dropping to moderate NW, temps 0 to -3, freezing level 1000-1300 m.

Wednesday - 1 to 3 cm of new snow (later in the day), winds light to moderate SW-SE, temps 0 to -2, freezing level 0-900 m

Posted on Monday February 10, 2020 by Bill Phipps

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