Investors might want to bet on Northwest Pipe Co. (NWPX) , as earnings estimates for this company have been showing solid improvement lately. The stock has already gained solid short-term price momentum, and this trend might continue with its still improving earnings outlook.The rising trend in estimate revisions, which is a result of growing analyst optimism on the earnings prospects of this steel pipe maker, should get reflected in its stock price. After all, empirical research shows a strong correlation ...