All you need to do to bring this storm to your kitchen is add 2 ounces of rum (Goslings Black Seal is the traditional recommendation) to a tall glass filled with ice and 5 to 6 ounces of ginger beer.
For a "darker" dark and stormy, swap the Goslings Black Seal rum for Goslings 151-proof at 75.5% ABV (and maybe scale it back ...