Severe T-Storm Photo and Hail Question

[Macintosh]

So, the following picture was taken from a location just west of a severe t-storm in Perryville, MO on 3/30 @ 7:15pm. The storm was moving east, so by the time this photo was taken the storm had already passed over us. Right after it passed, it was severe t-storm warned for large, "walnut-size" hail. It maintained a nice bright echo on radar that was almost surely a hail core, and did so for about a full hour after being warned.

My question is, from the photo, what is the large, curved area of precipitation seen in the middle of the photo? Is that hail, rain, or a microburst of some kind? This is the first time I've seen something shaped this way in person.