The honorary mentions - in no particular order - are:
Nick Vivian - Storm coming to Fjällbacka

Luxun 54 - Zabriskie Point at sunset

Clyne - Storm clouds on Bintan

I love your Alona Beach storm image a lot as well, but the clouds in the Bintan image are very intriguing.
Third place: Jarek M - On the edge of thunderstorm cloud. Brighton beach, Melbourne

Second place: Juan Leon - Arcoiris

First place: Marcel de Jong

A wonderful panoramic composition of great quality.
Congratulations to all, especially to Marcel: I'm looking forward to your contest's subject.