The Scientific Challenge of Space Weather Forecasting Anthony J. Mannucci 1 , Delores Knipp 2 , Huixin Liu 3 , Ryan M. McGranaghan 4 , Xing Meng 1 , Surja Sharma 5 , Bruce T. Tsurutani 1 , Olga P. Verkhoglyadova 1 1 Jet Propulsion Laboratory, California Institute of Technology, USA 2 University of Colorado, Boulder, USA 3 Kyushu University, Japan 4 ASTRA, LLC 5 University of Maryland Acknowledgements: NASA/NSF Partnership for Collaborative Space Weather Modeling Heliospheric and ITM Community of Model Developers Copyright 2019. California Institute of Technology. All Rights Reserved. Sponsorship of NASA Heliophysics Division.