test render using frame blending (high quality / optical flow) and 1000% time stretch in after effects cs3.
-cloud motion interpolates well. this technique looks promising for images without any sudden changes.
-obvious issues with the lightning. i was curious to see what after effects would do with those frames. i imagined the lightning slowing appearing out of the clouds over the course of a second or so. i didn't really imagine (or want) what it actually did.
-1.5 hour render time.
-i could try running this through twixtor, a 3rd party plugin for after effects that has more controls for time stretching.