Saturday, April 19, 2014 at 7:25am

Special Announcement

This is the last avalanche advisory of the season. If you appreciate weekend advisories and want to see more next season, please press our DONATE Button now.  A huge thank you to everyone who helped support HPAC this season!  Enjoy the spring snow!

This advisory expires in 24 hours

BOTTOM LINE

Moderate avalanche hazard at all elevations on south, east, and west aspects above 40° for wet-loose avalanches.

Low hazard on north aspects. Low hazard does not mean no hazard.   

 Click here for a description of the North American Public Avalanche Danger Scale

RECENT ACTIVITY and CONDITIONS

This past week consisted of few wind gusts ranging from 20-30mph earlier in the week. Nighttime temps remained in the 20′s, rising into the 30′s and hitting 40 degrees on Friday at 3500′. Significant daytime heating has saturated many snow surfaces, while nighttime freezing has kept avalanches to a minimum.

We have yet to see a significant spring shed cycle, however, wet-loose avalanches have been observed on south, east, and west aspects above 40 degrees.  These avalanches are small, and can be mitigated with good route finding and terrain choices. 

 

AVALANCHE CONCERN 1

Wet-loose avalanches have been observed all week on south, west, and east aspects, mostly above 40 degrees. On east and west aspects, these avalanches are running on a faceted crust 2-6″ deep.  Most of these avalanches have been initiated near rocks and/or bare ground.

On south aspects, especially at low and mid elevation, this crust (mentioned above) no longer exists,  and the top meter of the snowpack has become isothermic.  This equates to more unconsolidated snow that could contribute to larger wet-loose avalanches in the future.  When temperatures rise even more rapidly, and cease to freeze at night, wet-loose and wet-slab avalanches will become more likely.

Wet-Loose, East Aspect, 3800feet

Wet-Loose, East Aspect, 3800feet

 

AVALANCHE CONCERN 2
More info 
Building size cornices are still looming over leeward slopes.  Remember that cornices can be incredibly unpredictable.  Keep a safe margin of distance when route finding on and around these cornices.  As temperatures continue to rise, the stress/strength balance will be compromised, bonds will weaken, and cornices will start to collapse. It is a matter of time before they start breaking.  Cornices of this size have been known to crush, injure, or kill a person. Choose up-routes wisely to avoid unnecessary time and exposure to this hazard. 
 TREND

The weak low pressure system from Friday will move out and bring clear skies and sun for the weekend. Expect cloudy and warm weather, with some light precipitation to return early next week.

Expect avalanche danger to remain steady.  If the temperatures rise into the 40′s for several days, or cease to freeze at night, expect to see larger wet avalanches.

-Allie Barker

 

Below are some interesting graphs from the 2014 season:

                   Alaska Snow, Water, and Climate Services Data for Independence Mine                          Water Year 2014 Daily Snow Depth        

Red=current water year Blue=last water year

INDEPENDENCE_M_Snowdepth_140419

 

                                                              Water Year 2014 Daily Air Temperature                                                           Maximum Minimum Average

INDEPENDENCE_M_AirTemp_140419

 

 

If you are out and about HP and see an avalanche or have a snow observation, please share it with us by clicking on these links or under the observations tab in the menu bar or email us at info@hatcherpassavalanchecenter.org. We would like to hear from you!