The storm in this excellent tragedy, like the storm in King Lear, seems to operate on a literal, a thematic and a symbolic level. Firstly, of course it is a literal storm that threatens Othello's ships, but it is important to note the first line of Act II scene 1:
What from the cape can you discern at sea?
The storm is linked explicitly with lack of vision, as at the beginning of Act I of this play. Of course, the storm therefore also is used for foreshadow not only the lack of vision of Othello has after Act III, but the way that he is overpowered by a "tempest" of anger and jealousy. Thus it is vitally important to realise how Shakespeare is using this storm to develop the key theme of lack of vision and also to foreshadow the internal storm of emotions that prevents Othello from seeing clearly and also causes him to act in a way that destroys those around him, just as the storm in this scene destroys the Turkish fleet.