OK, so I'm not holding my breath for this, but one can dream...
Right now, all Sentinel targeted AoEs have a 40 foot range. This includes Storm Cell.
My suggestion is to increase Storm Cell's range to 60 feet to match Sentinel ST range.
The reason for Storm Cell specifically is that my understanding is SC is supposed to be cast at the beginning of a fight, and all other ATs that get Storm Blast can cast Storm Cell without aggro.
Sentinels, with only a 40 foot range, are well within minion aggro range *before* it is cast, meaning you either are forced to take a stealth power or forced to slot multiple Range enhancements or else you will take damage *before* casting an aggro free power.