A simile is a type of description that makes an explicit comparison between two things using the words "like" or "as." A metaphor, by contrast, is a direct comparison that does not use these words. You can use these devices to create surprising descriptions of your storm. If you're describing a hailstorm, for example, you might use a simile to write, "The hailstones clattered to the ground like marbles spilled from a box." To use a metaphor, you might write, "An avalanche of hailstones fell from the sky."
In real life, the sounds of nature are often key indicators of approaching storms. You can bring these sound effects to your descriptions by using onomatopoeia, a device where words mimic the sounds of their meaning. For example, if a thunderstorm figures prominently in your story, the thunder could "rumble" or "boom," rain could "patter" against the windows" and wind could "rush" across a field. Try making a list of all the sounds the storm in your narrative might involve and brainstorm onomatopoeic words to describe them.
If a storm is central to your story's conflict, you might consider having the weather literally take on a life of its own. Personification occurs when a writer gives human characteristics, such as actions and emotions, to an inanimate object. If your characters are trapped in open water during a hurricane, you might write, "The angry waves smacked against the side of the boat." Although water can't feel anger, the description of the waves as "angry" adds emotional texture and characterization to the storm.
Because bad weather can often get out of control, describing a storm is not the time to skimp on verb usage. Weak verbs, such as "was" or "were," drain your descriptions of energy rather than infuse them with detail. Using specific, active verbs for the storm's motion gives readers a more detailed image of the story's events. For example, the sentence, "The dark sky was lit up by lightning," is a good start, but revising it to include an active verb can make the description even more forceful: "Lightning flashed across the sky."