1 An Assessment of Subseasonal Forecast Skill Using an Extended Global Ensemble Forecast System (GEFS) Yuejian Zhu * 1 , Xiaqiong Zhou 2 , Wei Li 2 , Dingchen Hou 1 , Christopher Melhauser 2 , Eric Sinsky 2 , Malaquias Pena 2 , Bing Fu 2 , Hong Guan 3 , Walter Kolczynski 2 Richard Wobus 2 and Vijay Tallapragada 1 1 EMC, NCEP, NWS, NOAA, College Park, Maryland 2 IMSG at EMC, NCEP, NWS, NOAA, College Park, Maryland 3 SRG at EMC, NCEP, NWS, NOAA, College Park, Maryland Version 3.0 Update: 9/7/2017 In preparation to be submitted to Journal of Climate *Corresponding Author: Yuejian Zhu, Email: Yuejian.Zhu@noaa.gov, Environmental Modeling Center/NCEP/NOAA, 5830 University Research Court, College Park, MD 20740