Energy of a slide

To calculate the energy of an avalanche slide, I will use an avalanche that occurred in Turnagain Pass on December 18th, 2014. 
Before the snow releases and starts sliding it has potential energy. 
As the slab move down the slope that potential energy is converted to kinetic energy. 

To find the potential energy of this avalanche we need to look at the size of the slide and the density of the snow at this time. 

First to determine the mass of the initial slab we need to find the amount of snow we have. Because we know the density of water we convert the amount of snow to water. This was done by looking at the water equivalence recorded at the Turnagain Pass SNOTEL during the storm before the avalanche.
(26in)snow=(2.5in)water=(0.2ft)water
Now that we know the depth of water equivalence we can use the dimensions of the slab documented by CNFAIC
mass=(kg/m^3) ∙0.2ft∙300ft∙300ft∙(1m/3.28ft)
≅5500kg
Finally we can use our potential energy equation to find the total amount of energy initially in the triggered slab.
PE=m∙g∙z
PE=5500kg∙9.81 m/s^2 ∙(3200ft-2200ft)
≅53955 kJ
Thats approximately enough energy to supply electricity to a house for a month. 
Once the slab starts moving down the slope, the snow below it combines to form an even larger slab. This larger slab will also start moving faster and in turn gain more kinetic energy.