Regional and Mesoscale Meteorology Branch

Use of Ensembles in the Forecast Process (Cold Season Version)

Introduction

Medium and Short-Range ensemble prediction systems in a cold season context. Included will be a brief description of what data is available on AWIPS, a discussion of webpages that contain data beyond what AWIPS has (including the North American Ensemble Forecast System combining the NCEP global ensemble forecast system (GEFS) and the Canadian Meteorological Center ensemble forecast system (CEFS)).

There will then be case examples from the medium and short-range relating to probabilistic forecasting in the cold season, including:

1. Using the Medium-Range forecast to recognize long-wave and synoptic patterns conducive to significant cold season weather events.
2. For SREF, getting down to details in the forecast such as risk of freezing or frozen precipitation type, exceeding critical precipitation and temperature thresholds, and so on.

Training Session Options

1. VISITview playback without Audio – You may step through the VISITview file on your own to view the presentation. If talking points are available, you may use these in tandem with going through the slides.

   Create a directory to download the playback file from the following site: http://rammb.cira.colostate.edu/training/visit/training_sessions/use_of_ensembles_in_the_forecast_process_cold_season_version/use_of_ensembles_in_the_forecast_process_cold_season_version.exe

   After extracting the files into that directory click on the visitlocal.bat file to start the lesson. Advance slides on your own using the navigation controls (i.e., the Next button will advance to the next slide)

References/Additional Links

• Kalnay, Eugenia, 2005. Atmospheric Modeling, Data Assimilation and Predictability. Cambridge University Press, New York, 364 pp.
• Molteni, F., Buizza, R., Palmer, T. N., & Petroliagis, T., 1996: The new ECMWF ensemble prediction system: methodology and validation. Q. J. R. Meteorol. Soc., 122, 73-119.
• Toth, Z, & Kalnay, E., 1993: Ensemble Forecasting at NMC: the generation of perturbations. Bull. Amer. Meteorol. Soc., 74, 2317-2330.
• Tracton, M S, & Kalnay, E, 1993: Operational ensemble prediction at the National Meteorological Center. Weather & Forecasting, 8, 379-398.
• Zhu, Yuejian, Zoltan Toth, Richard Wobus, David Richardson, and Kenneth Mylne, 2002. The Economic Value Of Ensemble-Based Weather Forecasts. Bull. Am. Meteorol. Soc., 83, 73-83.