So instead of delayed damage from the ult (waiting for it to explode), it's instant (upon impact)? I like the concept, but to balance it maybe slow the rate at which the missiles hit the ground (a slower volley of missiles), or make the warning cues more apparent (i.e. flare for signal is brighter, incoming air strike sound is earlier, or a funny whistle affect that you see in cartoons that signals something is falling).
I do fear that this ult might be too similar to gibraltar's. Although this one is more of a carpet bomb and gibralatar's is more random.
