When you get to the part where Laurey is dreaming and she and Curly are dancing in the tornado, pay attention. The tornado is still in the background, but the wind has stopped. Silent tornado?? I think not.
The whole point of the part where the tornado comes in, is that Laurey is having a DREAM about Curley. The point of the dream is to show that Laurey really loves Curley no mater how much she denies it. Do all of your dreams make perfect sense? I do not think that a tornado without wind is going to matter much in the grand scheme of things. The tornado does not undermine the brilliance of Rogers and Hammerstein's music and Lyrics, or Agnes De Mille's choreography.