Severe icing AIRMETs may be issued when conditions exceed which threshold?

Severe icing AIRMETs are issued specifically to alert pilots about dangerous icing conditions that can significantly affect aircraft performance. The key threshold for these AIRMETs is the occurrence of freezing rain. Freezing rain creates a layer of ice on the aircraft surfaces and can lead to severe icing, making it crucial for pilots to be aware of such conditions for safety.

In aviation, distinguishing the various types of precipitation is vital for flight planning. Light snow showers or clear skies do not inherently present an immediate risk of severe icing. Furthermore, when no precipitation is expected, it would not warrant the need for an AIRMET regarding icing conditions. Thus, the acknowledgment of freezing rain as a significant factor in issuing severe icing AIRMETs underscores the focus on preventing hazards associated with aircraft ice accumulation.