Southeast Mountains

Today's Moderate danger is driven by a low likelihood but high consequence threat of triggering an avalanche that breaks on weak layers near the ground.  Be cautious of steep terrain that faces the northern half of the compass where snow depths are less than about 4 or 5 feet over sugary weak snow.   The safest riding is on southerly aspects or wind-sheltered terrain with deep, uniform snow coverage.  You can trigger a broad and thick avalanche from a shallow spot on the slope, which is likely what caused the tragic avalanche fatalities on Saturday in Northern Colorado.  

Wind slab instabilities from Saturday's storm are mostly healed. Stay alert for this relatively small hazard in consequential alpine terrain, and watch for small natural sluffs today on sun-baked slopes, especially in the Northwest Mountains which picked up more snow on Saturday.  Today's danger is primarily driven by our concerns for deep instabilities.  There were a couple of explosive triggered avalanches breaking on weak layers near the ground last week, and our last human triggered avalanche was on December 25th, when slabs were half the size.  This highlights the low likelihood element of our concerns (and cautious travel habits during the past few weeks).   Looking through our photo galleries below, the high consequence nature of the problem is equally obvious.  Because a triggered avalanche would be unsurvivable, it's best to give yourself a wide margin for error in your terrain choices and snowpack assessments.  

In today's forecast discussion, I'm going to give a detailed look around the compass and link to photos of avalanches from the last cycle on December 31st to describe the types of slopes that give us some lingering concerns.  Hopefully that's helpful.  

• West to North aspects.  Early season weak layers are fairly widespread on anything tilted north of due west.  Weak layers on a lot of west-facing slopes with a tilt of south melted off early season, especially at low elevations or on wind-scoured slopes.   Periods of extreme winds in the past few weeks have scoured slabs away on the most wind-exposed terrain.  Those slopes are obvious and safe, but won't offer attractive riding. The slopes that concern me the most are sheltered cirques or cross-loaded terrain features near and above treeline, where thick slabs exist but also have thin spots because of  seasonal wind erosion patterns.  That's where you might hit a trigger spot.  
• North to East aspects.  Early season weak layers and slabs are widespread on anything that didn't slide near the end of the holiday cycle.  Snow depths are also deepest on these aspects so it is now very difficult to trigger an avalanche where the entire season's snowpack exists.  My greatest concerns are near rock bands because they can have shallow spots (example A,  example B, example C), or in the shallowest parts of our forecast area from town towards CB South where slabs are thinnest.  We also have concerns for slopes that avalanched early in the cycle on mid-pack weak layers (around Christmas Eve) and have rebuilt thinner slabs over basal weak layers.  This is probably more of an issue in the shallower parts of our forecast area (Southeast Mountains).  For these latter two concerns, we are showing a higher likelihood for the problem in the Southeast Mountains.  
• Southeast to Southwest aspects.  Early season weak layers melted into strong crusts or melted off on these aspects.  Our snowpack tests continue to show that the smaller grained weak layers that formed in mid-December are generally healed.  We didn't observe any deep failures on south or southwest aspects with the 12/31 cycle, and we spotted only two avalanches that failed deeply on east/southeast aspects. (Example A: Raggeds Wilderness, Example B: Avery). We don't know if these were on early-season crusts or the mid-December weak layers.  Southerly aspects have the strongest and most trustworthy structures across our forecast area; confidence decreases as you turn from southeast to east at higher elevations.