The Data
The period of time used for this study is 1 January 2006 through 31 July 2009. In addition to the ensemble hydrologic forecasts, the study also verified the QPF forecasts that are used to generate the hydrologic forecasts.The Ensemble Pre Processor (EPP) is used to generate two types of ensemble QPF input data that can then be verified with EVS. For the first 48 hours, Days 1-2, 6-hour QPF-based ensembles are used. Beyond Day 2, climatologically-based precipitation ensembles are used. Precipitation data that are independent of the EPP data are used in the verification. Twenty-four hour totals of gauge-based mean areal precipitation are used for verification of precipitation data, compared to six-hour instantaneous observations used to verify streamflow.
