I saw someone came up with these numbers:

New storm does 130 damage over 5.72 seconds (22.7dps), with a 50% bigger radius (125% bigger area).

Old storm does 80 damage over 2.86 seconds (28.0dps)

I guess the previous PTR was supposed to be 14 dps, but it was bugged so it probably didn't even reach that

https://tl.net/forum/viewpost.php?post_id=28310036

https://www.reddit.com/r/starcraft/comments/1no3wse/psionic_storm_ptr_update/