From AMS Glossary
(German: shape or form.) In synoptic meteorology, a complex of weather elements occurring in a familiar form, although this term is not commonly used.
The complex, though not necessarily referring to basic hydrodynamical or thermodynamical quantities, may persist for an appreciable length of time and is often considered to be an entity in itself. An example of a gestalt is a warm front and its associated pattern of cloudiness and precipitation.