Height Contours 1000 hPa:
The isolines of height of 1000 hPa show only a very weak minimum in the area of the cloud spiral. This is typical for an
Instant Occlusion as the origin of the cloud spiral is a Comma and Commas need not necessarily be accompanied by intensive surface lows. If the very well developed cloud spiral was a classical Occlusion, the low center would be much more developed.
Height contours 500 hPa:
In the upper height field, there is a very extended trough, showing even a beginning cut off stage. This is very typical
for an Instant Occlusion because the origin of the cloud spiral is a Comma feature which is a phenomenon triggered by upper
air features. Usually the upper level trough is behind the spiral but in this case the development time was long enough to
lead to a very advanced upper level trough.
PVA 500 hPa:
PVA at 500 hPa shows only a very weak signal in the area of the Instant Occlusion spiral. This is not completely untypical
for such a situation and indicates that there is only a very weak movement of the trough.
PVA 300 hPa:
PVA at 300hPa is much more marked than PVA at lower layers. However, the relationship between the jet streaks and the PVA
maximum is not so usual; a PVA maximum should be more in the left exit region of a jet streak. On the other hand, the maxima of the jet streaks are not so pronounced in this case.
TFP:
The TFP follows the frontal Cold Front band and does not indicate the cloud spiral as a frontal band. This is very typical
for this conceptual model.
Equivalent Thickness:
Equivalent thickness shows only a very weak ridge in the area of the cloud spiral. This is as it is expected also in the
ideal situation. In case of a so well developed cloud spiral, the thickness ridge would be much more pronounced if it was a
classical Occlusion.
Temperature Advection 700 hPa:
There is WA in the area of the cloud spiral of the Instant Occlusion. This is expected also in the ideal case, however, it
is expected more to the north of the spiral. In this case the area of WA is more extended; on the other hand is it only a
very weak maximum of WA.