Okay, so, I was discussing this in the Discord. The Storm Elemental idea is neat, but I think we can take it a step further. It's a bit of a desperation move, but we are desperate.
Storm Elementals (Soul Transposal): Since our very first experiments with magic, we have seen that the minds of men are powerful things, capable of transposing their will onto others in devastating ways. Our control of the mind has gotten more refined, with time, and we reached the point that we could even create new minds to inhabit our storms and direct their actions. However, these minds are weak, and require the dedicated effort of many wizards to control and sustain.
Yet... why do we need to create new minds, when we have so many already at our disposal? They may be contained within mortal forms presently, but we have seen with spells such as Antichronic Reverbramancy that said connection is weak, and easily broken.
So. Take Winds of Ruin. At first, everything is normal. A storm is summoned, and a wizard exerts their will over it. However, rather than stop there, the wizard focuses more and more of themselves onto the storm, 'transmitting' their consciousness into the elements using a technique similar to Teletalk wands. Certain substances help the wizard detach themselves from their body, until at last they have become the storm, controlling it effortlessly, like they did their body before. The newly formed Storm Elemental is free to roam as far afield as it pleases, wreaking havoc on Arstotzkans wherever they may dwell.
Meanwhile, the wizard's mortal form is in a sort of 'coma'. A ritual will be devised to summon the wizard's soul back into his body when their rampage is complete... but if the ritual doesn't work, well... they're not dead. And their names will be remembered forever, as martyrs.
In other words... we make storms autonomous by, as it were, sacrificing wizards. Not literally! They aren't dead! Just, their souls and body have been separated, and it may not be possible to rejoin them.
...I'm not saying this is the best idea ever. But if we want to go down the Storm Elemental route, this would provide a lot more bang for your buck.
EDIT: Of the current suggestions... I like the Phoenix, and the Lightning Cannon. The Wind Machine just seems like it would be weaker than the LC. I think better explosives would be a force multiplier for our fliers/artillery, though.