2010 Physical Sciences Review » Biographies » Dr. Stephen S. Weygandt

Dr. Stephen S. Weygandt

Dr. Stephen S. Weygandt

Dr. Stephen S. Weygandt

Head, Assimilation Development Section

Global Systems Division


Dr. Weygandt directs the development of data assimilation systems that provide initial conditions for the Rapid Update Cycle (RUC), Rapid refresh (RR), and High-Resolution Rapid Refresh (HRRR) weather prediction models. The RUC runs operationally at NCEP and provides short-range weather guidance for many aviation and severe weather hazards, including thunderstorms, icing, low ceiling and visibility, and turbulence). The RR is an advanced replacement for the RUC that is undergoing final testing on ESRL supercomputers, with a planned operational implementation at NCEP in 2010. The HRRR is the first hourly updated, convection resolving model run in real-time on a CONUS-wide domain. The HRRR is a key component of the improved weather guidance that will enable the NextGen and Warn on Forecast capabilities.


  • B.S., Meteorology, Pennsylvania State University, 1984
  • M.S., Meteorology, Pennsylvania State University, 1991
  • Ph.D., Meteorology, University of Oklahoma, 1998

Research Interests

  • Data assimilation, especially initialization of thunderstorms with radar data
  • Regional and storm-scale modeling, ensemble post-processing, probabilistic forecasting
  • Verification methods, observation impact, and observing system simulation experiments


Dr. Weygandt joined NOAA in 2000 and his work has focused on improving RUC, RR, and HRRR forecast performance and working with forecasters and other users to best utilize weather guidance products produced from these models. This work involves regular interaction with operational meteorologists at the Storm Prediction Center, Aviation Weather Center, and all of the National Weather Service regions. In 2003, Dr. Weygandt developed the RUC Convective Probability Forecast (RCPF), which provides thunderstorm likelihood guidance to forecasters at the Aviation Weather Center. Dr. Weygandt is a member of the American Meteorological Society committee on radar meteorology.

Recent Publications

  • Weygandt, S., A. Shapiro and K. Droegemeier 2002: Retrieval of initial forecast fields from single-Doppler observations of a supercell thunderstorm. Part I: Single-Doppler velocity retrieval. Mon. Wea. Rev., 130, 433-453.
  • Benjamin, S.G., D. Devenyi, S.S. Weygandt, K.J. Brundage, J.M. Brown, G.A. Grell, D. Kim, B.E. Schwartz, T.G. Smirnova, T.L. Smith, and G.S. Manikin, 2004: An hourly assimilation/forecast cycle: The RUC. Mon. Wea. Rev., 132, 495-518.
  • Weygandt, S.S., A. Loughe, S.G. Benjamin, and J. Mahoney, 2004: Scale-sensitivities in model precipitation skill scores during IHOP. 22nd Conf. on Severe Local Storms, Hyannis, MA, Amer. Meteor. Soc.
  • Weygandt, S.S., and S.G. Benjamin, 2007: Radar reflectivity-based initialization of precipitation systems using a diabatic digital filter within the Rapid Update Cycle. 18th Conf. Num. Wea. Pred., Park City, UT, Amer. Meteor. Soc.
  • Weygandt, S.S., S. Benjamin, T. Smirnova, J. Brown, and K. Brundage, 2008: Hourly convective probability forecasts from an experimental RUC with radar data assimilation. Preprints 13th Conf. Aviation, Range and Aeronautics Meteor., New Orleans, LA, AMS