The subseasonal experiment (SubX) is a multi-model subseasonal prediction experiment. Seven global models are producing seventeen years of retrospective (re-) forecasts and one year of weekly real-time forecasts. Re-forecasts follow the SubX protocol that requires the years 1999-2015, at least three ensemble members, a minimum of weekly initialization, and at least 32-days in length. All data are output on a 1deg x 1deg grid. The re-forecasts are archived at the IRI Data Library for research...