Observation Date
4/17/2013
Region
Salt Lake
Location Name or Route
Brighton: Millicent to Wolverine Bowl, Chutes and Cirque, Figure 8, Stupid Chute Too
Weather
Sky
Overcast
Precipitation
Moderate Snowfall
Wind Direction
Northwest
Wind Speed
Moderate
Weather Comments
Skies were mostly clear in the morning until 1030 and then convective action appeared to influence building clouds and eventually one inch per hour snow squalls that began around 1400. These intermittent snow showers apppeared to continue until 1800. Winds were in the Light Catagory early on until around noon when the NNW winds began to accelerate. By 1400 the winds were in the Moderate Category with wind blown snow and or transport in the high end of the Moderate Range. These winds continued to be out of the NNW. Temperatures remained unseasonably cold throughout the day, with brief periods of obvious warming when the sun was out in force.
Snow Characteristics
New Snow Depth
4"
New Snow Density
Low
Snow Surface Conditions
Powder
Dense Loose
Wind Crust
Damp
Snow Characteristics Comments
In the beginning of the day the Southerly aspects at the upper elevations were still cold dry snow with no signs of m/f crusts from the previous day. By 1030 the SE and S aspects began to get damp and saturated. At this same point in time the lower angle terrain (less than 25 degrees) also began to get damp on all aspects. Wind scouring and crusts were evident on the upper elevation northerly facing terrain even before the winds picked up later in the day. In areas affected by the wind the surface snow was a bit more dense and compacted, yet totally ridable and fun. Before the sun adversely affected the other aspects and snow surfaces, the majority of the terrain out there had incredible, true deep winter like riding conditions. By the end of the day, there was still excellent riding on slopes on the upper third of the compass above 8700 feet.
Red Flags
Red Flags
Recent Avalanches
Heavy Snowfall
Wind Loading
Cracking
Rapid Warming
Red Flags Comments
The rapid warming came first, and the photos below depict the Wet Loose Snow Avalanche conditions that were observed and appeared to occurr around 1300 hours. With the increasing winds and heavy periods of PI there was obvious wind loading occurring on Southerly aspects, as well as cross loading on terrain features. Cracking in the upper couple inches of new snow was observed around 1600. The loading on the Southerly aspects appeared to settle out quickly as a result of the warm snow surface conditions. Yet, as these winds and precip rates appeared to continue on well into the late afternoon and early evening, there may have been more sensitive wind drifts from sunset and on. At 2100 hours the winds have not appeared to back down.
Also, there were a number Loose Snow Avalanches triggered by riders descending the steep West facing terrain in the Brighton Back Bowls. The public traverse was covered by debris that was 18 inches deep. These were observed around 1530. Finally, by 1500, good visibility indicated that most of the steep lines in the Wolverine Cirque had been ridden without any significant signs of instability.
Avalanche Problem #1
Problem
Wet Snow
Trend
Increasing Danger
Problem #1 Comments
Wet Avalanches were the number one avalanche problem on Wednesday. See photo. The additional few more inches of new snow (plus the wind loading), may combine with the sunny skies forecasted for Thursday to keep this an issue of concern. This hazard may actually be more active on Thursday in the upper elevations.
Avalanche Problem #2
Problem
Persistent Weak Layer
Trend
Increasing Danger
Problem #2 Comments
See above comments regarding the increasing and sustained winds out of the NW. These wind slabs may be sensitive in the morning hours and possibly settling out as the day goes along.
Wet Loose Snow Avalanche on the Southerly aspect off the Highway to Heaven
Another picture of the same avalanche. Of note: with many of the ski areas closed and or closing this weekend, terrain like this that is controlled all winter long must now be dealt with differently.
