An evaluation of stratospheric CAT forecasts for mid latitudes

The HICAT Program in Australia, which investigated the occurrence of CAT in the stratosphere, was carried out jointly by the U. S. Air Force and the Lockheed Company in July-August 1966. Paucity of both temperature and wind gradients in the stratosphere made the identification of criteria associated with CAT in this region very difficult. However, parameters such as Richardson's number combined with an instability index which was a modification of the Endlich-McLean parameter |VΔα/ΔZ|, proved to be helpful in determining search areas for CAT. An example of the method used to forecast CAT is given together with a statistical analysis of the indicators used in this exercise.