National Weather Service Professional Development Series Professional Competency Unit

Description of Job Duty Competency to be Achieved

Identify the temporal and spatial onset and evolution of low-altitude clouds and fog. The forecaster should appreciate the impact of the forecast on aircraft operations. The focus will be on a 0- to 12-hour forecast with additional emphasis in the 0- to 6-hour time window. Where applicable (e.g., DoD), the 12-72 hour time period is important. These forecasts may apply to all three horizontal scales.

Description of Need

Accurate forecasts of the development, movement and dissipation of low-altitude clouds and fog are needed to enhance aviation safety and economy. Aviation operations are impacted by low-altitude clouds and fog to the degree that these meteorological phenomena reduce visibility and cloud ceiling below operationally defined limiting values. Safety issues become more important as the ceiling height and/or the visibility decreases. There is a need for forecasters to develop skill in forecasting specific heights of low clouds and reductions in visibility due to fog.

Specific Job Task Skills and Knowledge

1. Utilize numerical models and gridded forecasts for large scale, regional scale, and mesoscale guidance for the fog and low clouds forecasts:

2. Anticipate atmospheric conditions important to ceiling and visibility forecasts by utilizing both observational data and the critical factors in the model data assessed in part (1) above:

Instructional Components

Instructional Component 4.1: Use and limitations of synoptic and mesoscale models in forecasting low-altitude clouds and fog. This will include the forecast elements listed in Task 1 above.

Instructional Component 4.2: Series of case studies which examine both observational and numerical model data for past events including severe fog episodes, notable stratiform events, and non-events.

Instructional Component 4.3: Interactive component in which students provide low-altitude cloud and fog forecasts and the corresponding ceiling and visibility values, and then assess the impact on aviation operations.

Instructional Component 4.4: Case studies illustrating the preparation and issuance of a military aviation ceiling/visibility forecast, including a sea fog case.

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