Mend on the Cast

Help a brother out here.

What's the trick to throwing an upstream mend during the forward cast?

I have trouble mending a line upstream without moving the fly when I'm making long casts. Threw to some risers last weekend and had great fly presentation, but I'd botch it when I tried to mend up. And when I didn't mend, obviously, no drag-free drift.

Thanks!

What he said.
 
You can also over power the cast and just as the energy transfers from the flyline to the leader, drop your casting elbow -- the energy dies, dropping the fly with the leader and the flyline upstream of the fly.

Everything they said is good. I like to cast hard then stop the cast and, like Jerry said roll the rod away from the fly into slacker water, usually your line will overshoot the fly and dump to the right/left of your drift. Then it is easy to make further mends without moving the fly. Also keep the rod tip up till you start the roll/mend and then drop it to just turn the line. This does however come with a downside as it makes for more slack line to take up when striking. Also it helps to reduce the movement of your rod tip practice making many small mends as opposed to one large one. And again, if the fly is in fast water and is dragging the line it is easier to side mend. Confused yet? Soon I'll explain the importance of using the solunar tables to determine fly line color.