Enroute Icing

### Produced by The COMET® Program

### Summary and References » Lesson Summary

This lesson uses a winter icing case in the Midwest to present a procedure to forecast enroute icing for aviation. It is summarized below.

First, observations and NWP analyses are evaluated to locate areas and flight levels in or near the forecast area that are currently at risk for icing. Then the consistency of the NWP analyses is reviewed by comparing them to observations. If they are similar, they can be used together to find initial icing conditions. The comparison also helps you know whether the model guidance will be useful in making the final forecast.

Next, you project current observations and model initial conditions to make a first forecast for enroute icing. If the initial icing conditions in the NWP model are consistent with the observations, the NWP forecast icing products are used to check the first forecast. The first forecast is adjusted, as needed, based on the NWP model icing forecast, and the final forecast, including flight levels and icing intensity, is made.

Many observation and analysis tools are available to guide icing forecasts at levels extending from the surface to the tropopause. The tools come from various sources, including METARs, radiosondes, aircraft pilot reports, and weather satellites.