Analog Forecast Model

This study investigates the skill of a single-predictor, constructed analog forecast system for the Northern Hemisphere. Using the operational daily 00Z Global Forecast System Model (GFS) 500 mb geopotential height field initialization and the NCAR Reanalysis daily 500 mb geopotential height data, a constructed analog model was developed to produce a 50-member ensemble forecast. These historical analog ensembles are used to create a 45-day forecast of daily 500 mb geopotential height anomaly probability distributions across the Northern Hemisphere. Forecast accuracy using the correlation between the ensemble mean and standard deviation, and the observed daily 500 mb height data over the 45-day forecast period are presented. The analog forecast accuracy is also compared against the accuracy of the 0-384 hr GFS/GEFS forecast.