I am doing another playthrough of the civil war on the Stormcloak side. I have done the civil war more than 20 times and I have never noticed there is a repeated arrow volley during the battle for whiterun.
http://minus.com/mb1WCWe9Ijk1xY
http://minus.com/mbg8UKjOu9xMRj

4,000+ hours and I'm still finding new things.

That's interesting. I've never noticed that before.

So, you always join the Stormcloaks?

I have joined the empire 11 times and stormcloaks 24 times.

Wow, that is cool. To accompany the catapults, then. But do they do any damage? And are you running any mods?

I'm an xbox user. yes they deal damage.