Added on: May 9, 2012
According to the October 2007 update to FAA advisory circular, Aviation Weather Services (00-45F), "The K-Index is a measure of thunderstorm potential based on vertical temperature lapse rate, moisture content of the lower atmosphere and vertical extent of the moist layer." The K-Index is a derived weather parameter that is best used to assess the potential for non-severe convection and heavy rainfall. In order to use the K Index successfully, understanding its limitations is paramount. While the current advisory circular provides a brief idea of how to interpret K Index values, the computation of the K Index was removed from this revision. Instead, this advisory circular simply references an older advisory circular, Aviation Weather (00-6A), last revised in 1975, which unfortunately doesn’t mention the K Index at all, much less how to derive it. In this workshop we’ll discuss how the K Index is derived, how it is best used to assess convective potential and identify its key limitations.