Before I really start this, I’d like to say I like what you came up with. It’s a solid baseline. I myself have been looking into volumetric, fluid sims, and such recently and I think I may be able to point you in a direction. I’ve done no VR stuff though, so what I know is only of what I hear.
Right so, making sure I understand this. You are making an Realtime effect that will be viewed in VR. The effect in question is basically a giant swirling smoke eye-of-the-storm. The player has a “45 degree angle” range to see this effect in VR. If there are any other limits, which would make this so much easier, please say so.
TL;DR - Don’t think about this so literality. VFX is a creative technical art, fake it if you can. Shoot that’s kind of games in general, but I digress
The VR thing is the biggest kick in the pants, as now you have to design what it looks like to put your head into the storm here as well as not drop the framerate. To me, that says Post Process Effect. Smudge the lens. Something like this. Since you are in VR, that also means you’ll have issues if you use standard camera facing cards, as they will move as your head moves, and break the effect. I recall seeing something by @Wyeth that talks about fixing these sorts of errors, but I don’t recall what. Sorry 'bout that. You’ll probably have to fake the volumetrics too. Again, I like what you made, but I have to wonder about the frame rate when this is in VR with whatever else(?) is in your project. If your project is just this, then maybe you’ll get away with it? Not sure.
Again, I’m making alot of assumptions here. I presume you want a giant swirling storm looking thing. I’ve been playing around with spawning volumetric fog off of meshes with particle systems in Unreal 4, and I think the resolution you would need to give proper fidelity would be prohibitive. Plus, on animated meshes (in my case a biped) the fog takes noticeable time to update each frame, and it’s not fluid. The voxels are obvious.
In other words, how good are you with shaders? To me, going fully mesh based in your VFX would be the best bet if mixed with Post Process.
It’s a lot of work you got for yourself here, as the motion is the silhouette. I don’t know if you could get away with this in VR, but… MAYBE you could get away with some Tessellation hackery? I don’t know. Again, VR VFX is not in my observed study at the moment.
I would recommend in search looking up Skybox or Skybox VFX, as that’s basically what you are doing anyway.
That’s what I have at the moment, no idea if any of this helps but… eh. ¯\(ツ)/¯
Goodluck on your project. 
3 Day Later Edit: Was lurking through the RTVFX Search, and came across something that looks pretty much like you’re going for basicly 1-to-1. Had to share. Looks like @Spyro is your go to guy here! His #22 work is good but #12 over here… MMMM.