Avalanche Forecast
Issued: Dec 8th, 2014 8:25AM
The alpine rating is Storm Slabs and Persistent Slabs.
, the treeline rating is , and the below treeline rating is Known problems includeThe storm is expected to bring strong winds and rapidly rising freezing levels. Expect avalanche danger to increase as the storm develops.
Summary
Confidence
Fair - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
The storm system is expected to bring 5-10mm of precipitation to the Purcells region on Tuesday. Winds are expected to increase to strong from the SW and freezing levels will climb to around 2000m by Tuesday afternoon. On Wednesday and Thursday, freezing levels should remain around 2000m and winds will remain moderate or strong in the alpine. There is currently some uncertainty regarding precipitation amounts for Wednesday and Thursday with models currently showing another 10-30mm.
Avalanche Summary
Report of an isolated size 1 wind slab triggered by a ski cut in a steep gulley on Sunday.
Snowpack Summary
New snowfall sits on a layer of surface hoar. Another 15-20cm below this you may find a hard rain crust. In the Golden area this crust exists up to around 1600m, whereas in the south it is up to 2000m or higher. In total, last week's storm produced slabs up to 1m thick in the north of the region and around 60cm thick in the south. This slab sits on the mid-November weak layer (surface hoar, facets, and/or a crust). Below this you will likely find a 15-20cm thick layer of sugary facets, which is sitting on a solid rain crust from early November. The reactivity of these layers may be slowly diminishing, but they still warrant cautious consideration. Snowpack tests are getting hard pops and drops results, indicating the potential for large propagation and large avalanches.
Problems
Storm Slabs
Storm slabs will continue to build as the storm progresses. Initially wind slabs will be the main concern but the problem will become widespread as the storm progresses.
Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>Minimize overhead exposure; avalanches triggered by windloading may reach run out zones.>
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
Likelihood of triggering a deep weak layer is expected to increase with new storm loading and warming. Any slopes that did not avalanche during the last storm cycle should still be considered potentially hazardous.
Avoid common trigger zones including thin snowpack areas, near rocky outcrops, and steep alpine slopes.>Choose well supported terrain without convexities.>
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 9th, 2014 2:00PM