Avalanche danger for Grand County ‘considerable’
December 22, 2010
The avalanche danger for the Front Range zone, which includes the Vasquez Mountains, Winter Park and the Continental Divide from James Peak through the Never Summers is overall CONSIDERABLE (Level 3), according to Colorado Avalanche Information Center forecaster John Snook in his Dec. 22 report.
North America has adopted new definitions for the danger scale this season. Learn more about the warning scale at avalanche.state.co.us.
Snook stated in his report that no more than an inch of new snow has fallen during the past 24 hours across the Front Range zone. An observer around Jones Pass noted the Monday night snow to be lighter than the Sunday snow. A few signs of instability included a large collapse on a wind loaded southeast roll. Observers in the Eldora area found about 20″ of storm snow at 10,500′. The skiers were able to penetrate to a buried crust layer, and sometimes to ground with ski cuts. Wind effects were relatively minimal for this usually windy location. Signs of instability included a good whumpf but little propagation of cracking. No slides observed. Further north, observers in RMNP triggered a number of smaller surface sluffs and one larger slide on a northeast aspect at 11,600′, soft slab, 1-2′ x 500′ x 600′. A couple of smallish natural slides on southwest aspects put enough debris on the highway to close Cameron Pass.
The recent storm cycle is over for the Front Range. Signs of instability suggest that human-triggered slides remain probable in the reactive storm slab. These slabs could break down to persistent buried weak layers to generate larger slides. Although wind speeds have diminished, recent wind slab development is prevalent on northwest through northeast to southeast aspects. The avalanche danger is just starting to trend downward, but continue to use caution following the most recent storm cycle. Watch for signs of instability, such as collapsing, cracking, and previous avalanche activity. Modify your terrain selection if you find these signs of instability.
Southwest flow ahead of a low pressure trough digging into the Southern California coast continues to fuel orograhic snowfall favoring southwest aspects. Mild temperatures and light to moderate ridgetop winds continue with no real changes through Thursday. Heavy snow continues for the Southern San Juan zone and to a lesser degree for the southern end of the Northern San Juan, Grand Mesa, and Gunnison zones, plus the Flat Tops. Southwest flow has effectively cut off any significant snow for the northern and eastern zones. The low pressure trough works its way inland and reaches Colorado by Thursday evening. Winds shift to northerly ushering in cooler and drier air. All precipitation ends by midnight. High pressure slowly works into Colorado through the holiday weekend with partly cloudy skies and seasonably mild temperatures.
This information was provided by avalanche.state.co.us.