Medium-range (0-9 day) forecasts of the state and evolution of the North Pacific jet stream

This dataset contains 30 cool seasons (September–May 1985–2014) of ensemble forecasts that describe the forecast state and evolution of the North Pacific jet (NPJ) stream in the context of its two-leading modes of variability. NPJ forecasts are derived from 250-hPa zonal wind data included as part of the Global Ensemble Forecast System (GEFS) Reforecast Version 2 dataset (Hamill et al. 2013, https://doi.org/10.1175/BAMS-D-12-00014.1), feature 11 ensemble members, are initialized daily at 0000 UTC, and feature forecast lead times extending to 216-h at 6-h intervals. More detail on the construction of these forecasts is provided in Winters et al. (2019; https://doi.org/10.1175/WAF-D-18-0106.1).