Explaining a Physics Phenomenon with a Snowy Photo

[Jstuff]

Homework Statement

I have to submit a photo for a physics contest. I was thinking of using the picture in the attached, but I'm having trouble trying to figure out how to explain it in terms of physics. The background on the picture is: We had a very wet snow and as the snow built up on top it got to heavy and slid down the side of the play set but it stopped and created and sort of parabolic arch with supporting the middle. ( See attached picture.)

The Attempt at a Solution

I was thinking I could say as the snow accumulated on top of the play set the normal force was eventually exceeded by weight of the snow. As it was sliding down the frictional forces slowed it to a slow enough pace that the snow froze in place.
Is there anything wrong with this statement? Also, are there any other forces I should take into account?
Thanks in advance!

 

[217 MeV]

Not quite parabolic, try hyperbolic!

 

[Jstuff]

Thanks, but why exactly? Also, does anyone have any other ideas?

 

[217 MeV]

Well, I could derive why it produces a hyperbolic cosine here, if you like? With regards to a qualitative explanation, I'm sure someone else can provide a clearer answer than myself.