This page contains 5 and 7-day Quantitative Precipitation Forecasts (QPF) from the NCEP National Blend of Models (NBM) and the percentage of monthly and water year normal precipitation the forecast precipitation is equivalent to. The monthly and water year normals were calculated from PRISM gridded precipitation estimation data. The NBM QPF data was re-gridded to match the 4 km by 4 km scale of the PRISM data using bilinear interpolation.

Caveat: Since this product is created using two different precipitation data sets, percentage values may be inaccurately high or low. For example, there may be a dry bias over a specific location in the PRISM data set where the NBM forecast may have a wet bias over the same location. This situation would lead to a product that exhibits exacerbated percentages of normal over that location. This product should be used with this potential caveat in mind.

Images considered experimental. Produced by Chad Hecht (Contact)