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Avalanche Forecast

Feb 1st, 2018–Feb 2nd, 2018
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable

Regions: South Rockies.

Snow forecasts are uncertain and the snowpack is untrustworthy. Conservative decision making is critical.

Confidence

Low - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

Clashing fronts make the next few days difficult to forecast. A Pacific warm front and an Arctic cold front are converging over the Rockies, creating the potential for surprise accumulations of low density snow. Timing, location, and intensity are highly uncertain (and so are the snowfall estimates).FRIDAY: The first wave of snow starts Thursday night with 5-15 cm then another 5-10 cm possible throughout the day on Friday / moderate west wind / alpine temperatures around -5 C.SATURDAY: Continued flurries with 5-20 cm possible / strong northwest wind / alpine temperatures around -5 C.SUNDAY: Ongoing flurries / strong west wind / alpine temperatures around -3 C.

Avalanche Summary

On Thursday, a few small slabs were triggered by skiers in the southeast part of the region. The slabs occurred in the top 20 cm of new snow. A few natural wind slabs up to size 2 were also reported throughout the region over the past three days.A few large persistent slab avalanches were observed this week (up to size 3), but likely occurred during the warm stormy weather on Sunday and Monday. Many of these avalanches failed on the deeper November and December weak layers, and many were triggered by cornices falling on north and east facing slopes.

Snowpack Summary

Expect waves of fresh snow over the next few days as storm snow accumulates. The distribution will be spotty, as some areas already have 30 cm and others nothing. Stay aware of the condition of the new snow. Mostly low density powder is expected, but could become heavy if it warms up. Also watch for slab development in wind affected areas.About 20-50 cm of recent snow covers a weak layer that was buried in mid-January. It is composed of feathery surface hoar in sheltered areas and a sun crust on solar aspects. Another surface hoar layer from early-January is buried 30-60 cm deep. A widespread weak layer from mid-December is composed of facets, crusts, and surface hoar and is now buried 60-80 cm deep. Finally, a weak layer of rain crusts and sugary facets buried in late-November exists near the base of the snowpack. Although the snowpack structure is variable across the region, these persistent weak layers are generally widespread. Snowpack depths are also variable across the region and typically thinner in northern areas than in areas to the south.

Avalanche Problems

Wind Slabs

New snow and wind will form fresh wind slabs in higher elevation lee terrain. Large fragile cornices are also likely near ridge crests.
Be cautious as you transition into wind affected terrain.Minimize exposure during periods of heavy loading from new snow and wind.Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2

Deep Persistent Slabs

Several deeply buried weak layers have the potential to produce large destructive avalanches.  Avoid exposure to overhead avalanche terrain, including cornices which have been a common trigger.
If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.Minimize exposure to overhead avalanche terrain, large avalanches may reach run out zones.Be aware of thin areas that may propogate to deeper instabilites.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 2 - 3