A fantastic blog post by Mr. Juha Aaltonen of the Freshwater Centre of Finnish Environment Institute SYKE.  In his post, Mr. Aaltonen discusses river ice breakups and the advantages of incorporating uncertainty into river ice modeling in HEC-RAS.  He was able to do this by harnessing the power of the HECRASController as detailed in "Breaking the HEC-RAS Code".

While his post is specific to river ice breakup modeling, uncertainty can be used for just about any HEC-RAS application.  Give Mr. Aaltonen's post a read here:

http://www.hyokyaaltonen.fi/consideration-of-river-ice-breakup-uncertainties-in-hec-ras/