Reprocessing of Historic Hydrometeorological Automated Data System (HADS) precipitation data

Recently, the National Oceanic and Atmospheric Administration's National Climatic Data Center (NCDC) began archiving historical HADS precipitation data as a potential complement to the existing Cooperative Observers (COOP) precipitation data. Since its inception, HADS has been functioning as a real-time data delivery system to support the National Weather Service's warning and forecast mission. In addition, HADS became an important component of the operational Multisensor Precipitation Estimate (MPE) algorithm that combines rain gauge measurement and radar rainfall estimates from the Next Generation Weather Radars (NEXRAD). Rain gauge measurements from HADS are used in the MPE algorithm for bias correction of the NEXRAD precipitation estimates. Mean field bias and local bias procedures using the HADS precipitation data are run in real time, and this constraint often allowed for gross errors to go unnoticed in the data. At the beginning of archiving HADS data, NCDC began assessing the precipitation data for its utility as climate records. This assessment consists of reprocessing raw Shared Hydrometeorological Exchange Format (SHEF) precipitation variables with added quality control and assurance (QC/QA) to correct apparent encoding errors and to recover missing data. Many missing reports were recovered and corrected to no rain values as long as accumulated precipitation values are the same before and after the missing interval. We present examples of reprocessed hourly precipitation data that are analyzed in conjunction with real-time hourly precipitation data processed elsewhere (e.g. The National Center for Environmental Prediction).