The isentropes of the equivalent potential temperature show a Cold Front inclined crowding zone. In the ideal case the model separates the front and the Comma during the first stages of development. But because of the resolution problems of the model mostly only a broad Cold Front - inclined crowding zone can be observed. Within the lower layers of the troposphere the isentropes very often show potentially unstable behaviour below the Comma.

The field of vorticity advection shows PVA within the area of the Cold Front as well as within the area of the Comma - like cloudiness. The values of the PVA are increasing with height. During the Instant Occlusion development the two PVA maxima merge.

The lower and the mid-levels of the troposphere are characterized by convergence. The main maximum can be found within the Cold Front accompanying the frontal zone. A secondary maximum can be found within the area of the Comma - like cloudiness in low and mid-levels within the unstable zone. This convergence changes to divergence in the upper levels of the troposphere.

According to the vertical distribution of the divergence, omega shows strong upward motion within the whole area. The strongest upward motion can be found in the area of the Cold Front.

The pixel values of the IR and WV images show two maxima. The main peak represents the area of the Cold Front and a lower peak the area of the Comma - like cloudiness. A minimum of the pixel values can be found in the area in between, the so-called shallow moist zone, which is also situated at the cyclonic side of a superimposed jet stream, and therefore this minimum is extremely distinct in the WV image (see Meteorological physical background and Key parameters ). The pixels of the VIS image are characterized in the case of a shallow moist zone by high values over the whole area, but in the absence of such a zone by a local minimum between the Cold Front and the Comma - like cloudiness of the Instant Occlusion.

The isentropes of the equivalent potential temperature show a broad Cold Front inclined crowding zone. The location of the Cold Front can be found between the gridpoints 14/19 and 17/21. The Comma - like cloudiness is situated between the gridpoints 12/18 and 13/19.
The field of vorticity advection shows within the area of the Comma - like cloudiness increasing values with height, with a local maximum at approximately 400 hPa.
Convergence can be found within the area of the Cold Front and within the lower and mid-levels of the troposphere within the area of the Comma - like cloudiness.
As a consequence of the field of divergence, upward motion can be found within the area of the Cold Front as well as within the area of the Comma - like cloudiness. The strongest upward motion can be found within the Cold Front.