Phew! Okay, this one took a long time to make.
I started by creating a basic "rocking ship" shape animation (I did "cheat" a little and used the rotation tool in Grafx2 to create crude frames which I then refined a bit) and the silhouette of the ocean with the waves caused by the ship.
Animating the clouds was rather easy- the trick was to find the correct phase for each cloud "layer".
I then created the basic rocky tileset (about 8 tiles plus two big rock tiles), and animated some of them with some subtle water dripping effects (plus the splish effect for the topmost tiles). Manually placing the animated tiles on the background took a long time, but I think it was worth it.
I tried to slow down the ship movement, so I interpolated the frames manually by using the neat sieve option in grafx2. The result is that the background layers (clouds and the ship) have a 16-frame animation cycle, while the foreground has 8.
I then made the tree and "bush" sprites as a separate 8 frame animation, added the rain splish effects (which actually took a VERY long time) and placed it on the main scene.
After tweaking the color palette (I used colors from Dawnbringer's 16col palette and shifted the darkest "purple" to "blue"), I added in the rain from yet another separate animation.
I then added more animation cycles to make the whole thing longer.
Finally, I palette-shifted a few frames to create the lighting effect, and added in the lightning bolt on top of the animation. With properly set up shortcuts in grafx2 for switching between animation frames, drawing the lightning bolt animation was both easy and fun to do.