Results of an evaluation of the technique currently used in the National Weather Service River Forecast System to analyze precipitation in mountainous areas is presented. This technique, known as “Mountain Mapper” uses PRISM precipitation climatologies to assist the spatial analysis of gage precipitation amounts. In the NWSRFS this technique is applied to daily and to 6-hr precipitation amounts. The evaluation procedure estimates daily precipitation amounts at gaged locations and compares the results to the gaged amount. This estimate is also compared to precipitation estimates made without considering orographic effects. The results show that the Mountain Mapper approach is clearly better than not using it at all. Some suggestions on how to improve the approach using forecasts from an atmospheric model and using simplified approximations to atmospheric models will be discussed.