What is usually the atmospheric condition just prior to a trowal formation?

Trowals, or troughs of warm air aloft, are typically associated with specific atmospheric conditions that support their formation. Prior to a trowal formation, the atmosphere often exhibits widespread cloud cover. This cloud cover indicates a significant amount of moisture in the air and can suggest the presence of a warm air mass over a cooler surface, which is a common context for trowal development.

Widespread cloud cover is indicative of the lifting and cooling of air, which allows for the condensation of moisture and the formation of clouds. When warm air rises, it can lead to various weather phenomena, including the development of trowals. The presence of extensive cloud cover implies that the weather is dynamic and that there is an interaction between different air masses, which is essential for trowal formations to occur.

In contrast, prior conditions such as stable weather or rising temperatures may not provide the necessary dynamics for a trowal to develop, and severe wind shear may disrupt the formation processes rather than support them. Therefore, the presence of widespread cloud cover is critical as one of the atmospheric conditions leading up to trowal formation.