A quick step through on how to create a layered picture.
1. Starting with a dark background layer.
2. Add a layer with lighter elements using a soft brush.
3. Add a layer with streaks of light to simulate rain. Note that I have not added rain to the ground - and have reflected heat in some of the upper rain elements.
4. Add a layer with your model - using dodge and burn tools to reflect background light into this layer and to emphasize features.
5. Add a layer introducing new fire, ash embers and light sources.
6. Finally, add a final layer, using the linear dodge blend mode to create illumination and the illusion of fire.