Could've been for the challenge but I only took this tonight, and i'm unsure how much my post editing would have affected its entry anyway (sun rays and colour burning/overlay to increase contrast/vividness).
Print available upon request (ie: i'll upload hi-res image)
the trees create an almost symetrical effect along the horizon, which i thought was kinda cool, and their size also helps enhance the impact of the sky.
But that's just my opinion :-)
On a 30x20 print they're not too small - remember you're looking at a tiny preview, this shot is intended for poster sized printing ;-)
The low horizon and contrast in the clouds make for a dramatic image however I feel that the trees on the horizon are a touch too small to carry any kind of weight in the image leaving it a bit unbalanced.