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Archived

Avalanche Forecast

Apr 3rd, 2014–Apr 4th, 2014
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
4: High
The avalanche danger rating at treeline will be high
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable
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
3: Considerable
The avalanche danger rating below treeline will be considerable

Regions: Northwest Inland.

Confidence

Fair - Intensity of incoming weather systems is uncertain

Weather Forecast

Synopsis: Friday looks cool and dry, and then a series of weak systems should deliver small amounts of precipitation through the weekend. There's potential for significant precipitation, extreme winds and freezing levels in excess of 2000m beginning Sunday night.Friday: Freezing Level: 700 - 1100m Precipitation: Trace; Wind: Treeline: Light, SW | Ridgetop: Moderate, SWSaturday: Freezing Level: 900m - 1300m; Precipitation: 1:10mm - 1:15cm; Wind: Treeline: Moderate, S/SW | Ridgetop: Strong, SWSunday: Freezing Level: 1000m - 1200m; Precipitation: Trace; Wind: Treeline: Moderate, SW | Ridgetop: Strong, W/SW

Avalanche Summary

No new avalanche activity to report from Wednesday. I suspect avalanche activity ramped up Thursday, check tomorrow's discussion for more details.On Tuesday a steep rocky NE facing feature at 1900m released naturally resulting in a size 3 avalanche. Some natural cornice falls were reported, but they did not trigger slab avalanches on the slopes below.

Snowpack Summary

The storm has produced 10 - 20cm of new snow as of Thursday afternoon. This snow rests on surface hoar, small grained facets and melt freeze crusts.Previous to Thursday's snow, it was starting to feel like spring in the NW. Valley temps have been creeping into the double digits during the day, and there are reports of the top 15 cm of the snowpack regularly becoming moist with daytime heating.Prior to the snowfall Thursday, the last significant shot of snow was on March 27th, another 10 - 15 fell on March 30th. This old storm snow rests on top of a haggard old surface composed of old wind slab, melt freeze crust, and faceted old snow. I suspect the ongoing melt freeze cycles have largely healed any instabilities associated with this interface.The early March layer can be found down 75 - 100cm and is composed of facets/surface hoar on shady aspects and facets/crust on southerly aspects. The early February crust/facet/surface hoar combo is down 150 - 200cm, and I suspect it's gone mostly dormant for now.

Avalanche Problems

Storm Slabs

New snow driven by strong ridge top winds has likely created touchy slabs at and above treeline. This snow is not expected to bond well to the current crust/surface hoar combo and will likely remain sensitive to human triggering Friday.
Minimize exposure to overhead avalanche terrain, large avalanches may reach run out zones.>Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Stick to simple terrain and be aware of what is above you at all times.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 5

Deep Persistent Slabs

Two buried weak layers exist in the snowpack. These weak layers could be activated by cornice fall, a smaller surface avalanche in motion, or a rider finding the sweet spot, which would be most likely in steep rocky terrain.
Be aware of thin areas that may propogate to deeper instabilites.>Extra caution needed around cornices with current conditions.>Be aware of the potential for large, deep avalanches due to the presence of buried facets and surface hoar.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 3 - 7