This Webcast is based on a COMET classroom presentation by Dr. Gary Lackmann at the 2nd MSC Winter Weather Course held in Boulder, Colorado on 22 February 2002. Dr. Lackmann reviews the basic thermodynamics of freezing and melting and how operational models represent these processes. He also touches upon the biases that occur in the models by looking at examples of melting snow aloft, melting snow at the surface, freezing aloft (ice pellets), and freezing rain. Dr. Lackmann is a faculty member in the Department of Marine, Earth, and Atmospheric Sciences at North Carolina State University.
1. Examine four thermodynamic scenarios closely, each of which produces a different precipitation situation.
2. Compare sounding, radar, and model signatures associated with these scenarios.
3. Compare the representation of these thermodynamic processes in operational models at and near the surface.
4. Become aware of potential problems with the model forecasts.
5. Examine the limiting processes and requirements for freezing rain.
Freezing and Melting, Precipitation Types, and Numerical Weather Prediction
July 2014: Older NWP models are used in this module, but the focus is on basic physical processes, so the lesson remains relevant and useful.
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