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Regional and Mesoscale Meteorology Branch

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TROWAL Identification


Scott Lindstrom

Scott Bachmeier

Jon Martin



Winter / Sat





Last Updated:



TROWAL stands for TROugh of Warm air ALoft


  1. Learn more about extratropical cyclone structure
  2. Learn how to use AWIPS to find TROWALs
  3. Can TROWAL identification help forecast accuracy?


  1. Review conceptual models of cyclone airflow
  2. Review vertical motion
  3. Historical review of TROWALs
  4. Characteristics of TROWALs
  5. How to find TROWALs
  6. Case study

Training Session Options

NOAA/NWS students – to begin the training, use the web-based videoYouTube 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 (92 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. Live VISIT teletraining (with an instructor leading the session). Check the VISIT Training Calendar to signup for teletraining. The session will last 75 minutes. This teletraining session uses the VISITview software, where a Windows PC with an Internet connection is needed. Please follow the teletraining installation instructions to install the session.
  3. You Tube Video


References/Additional Links

  • Talking points are available for this lesson and may be printed out to easily review the session in detail at any time.
  • Crocker, A. M., W. L. Godson, and C. M. Penner, 1947: Frontal Contour Charts. J. Meteor., Vol. 4, 95-99.
  • Godson, W. L., 1951: Synoptic properties of frontal surfaces. Quart. J. Roy. Meteor. Soc., Vol. 77, 633-653.
  • Penner, C. M., 1955: A three-front model for synoptic analyses. Quart. J. Roy. Meteor. Soc., Vol. 81, 89-91.
  • Martin, J. E., 1998a: The structure and evolution of a continental winter cyclone. Part I: Frontal structure and the occlusion process. Mon. Wea. Rev., Vol. 126, 303-328.
  • Martin, J. E., 1998b: The structure and evolution of a continental winter cyclone. Part II: Frontal forcing of an extreme snow event. Mon. Wea. Rev., Vol. 126, 329-348.
  • Martin, J. E., 1999: Quasigeostrophic forcing of ascent in the occluded sector of cyclones and the TROWAL airstream. Mon. Wea. Rev., Vol. 127, 70-88.
This course is Basic

If you have not taken the VISIT Cyclogenesis session, it is recommended that you either signup for the Cyclogenesis teletraining OR go through the audio version before taking the TROWAL session.


Scott Lindstrom

Scott Bachmeier 

Page Contact

Bernie Connell