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Top Ten Misconceptions about Numerical Weather Prediction (NWP) Models


Stephen Jascourt

William Bua



Archived Training





Contributors: UCAR/COMET staff (graphics), Richard Cianflone, Andy Edman, Michael Staudenmaier, Tony Mostek, Brian Motta, Dan Bikos


The material in this session is designed to introduce you to ten of the most commonly encountered or significant misconceptions about NWP models, and to dispel these misconceptions with the truth about what these models actually do and how they may be used intelligently. This “top ten” list should not be considered exhaustive, by any means, but rather a sample of misconceptions from each of the main components of NWP models, including:

  • Data assimilation.
  • Numerical calculation methods, including model resolution.
  • Physical parameterizations.
  • Post-processing of model forecast output, including MOS.

We hope to encourage use of the COMET web-based training on NWP through giving a flavor of the material therein contained in this lesson.

Training Session Options

NOAA/NWS students – to begin the training, use the web-based video, YouTube video, or audio playback options below (if present for this session). Certificates of completion for NOAA/NWS employees can be obtained by accessing the session via the Commerce Learn Center

  1. Audio playback (recommended for low-bandwidth users) – This is an audio playback version in the form of a downloadable VISITview and can be taken at anytime.

    Create a directory to download the audio playback file (24 MB) from the following link:

    After extracting the files into that directory click on either the visitplay.bat or visitauto.bat file to start the lesson. If both files are present, use visitauto.bat

  2. 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:

    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

COMET Numerical Weather Prediction Professional Development Series

COMET NWP Training Course

The course provides a pathway through the most important sections of these modules, but each can be viewed independently and in their entirety:

For specific information about the operational models (topography, resolution, physics parameterizations, data used in model analyses, etc.), use the one-stop shopping Operational Model Matrix page. This also has links to the above NWP training modules.

A series of case studies illustrating some operationally significant aspect of the NCEP models will be developed during mid-2001. The first is already online: When Good Models Go Bad: Eta, SSTs, and Prediction of the December 30, 2000 East Coast Snowstorm, Available here

This course is Basic

Experience in using numerical weather prediction models in an operational environment is very helpful. This is a basic to intermediate course. Those who have taken coursework in numerical weather prediction will find some of the information basic, depending on the emphasis of that course (numerics and dynamics alone, or additional coverage of physical parameterization methods). The reference section below gives links to source material for additional discussion of the inner workings of NWP models, to help the students gain additional understanding of how to intelligently use the information that NWP models provide to make the most accurate forecast possible for their CWA.


Dan Bikos

Page Contact

Bernie Connell


Unless otherwise noted, all content on the CIRA RAMMB: VISIT, SHyMet and VLab webpages are released under a Creative Commons Attribution 3.0 License.