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NOTE: The winds aloft forecasts were formally known as FD. 

## Composite Moisture Stability Chart 

The composite moisture stability chart is a four-panel chart, which depicts stability, precipitable water, freezing level, and average relative humidity. It is a computer-generated chart derived from upper-air observation data and is available twice daily with a valid time of 0000Z and 1200Z. This chart is useful for determining the characteristics of a particular weather system with regard to atmospheric stability, moisture content, and possible aviation hazards, such as thunderstorms and icing. [Figure 9-35] 

For the purpose of soaring flight, the stability panel located in the upper left corner of the chart [Figure 9-35 Panel A] can be useful when obtaining weather as it outlines areas of stable and unstable air. The numbers on this panel resemble fractions; the top number is the lifted index (LI) and the lower number is the K index (KI). [Figure 9-36]  The LI is 

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