Height Contours 1000 hPa:
There is a large and deep surface low with minimum values close to the center of the cloud spiral. This conforms with the ideal configuration of the conceptual model for a Cold Conveyor Belt Occlusion.
Height contours 500 hPa:
There is a pronounced upper level trough at the rear of the cloud spiral. This is typical for this conceptual model. And
additionally it is also typical that there is still a trough and not yet a closed upper level low. The latter would be more
typical for a WCB Occlusion.
Isotachs 300 hPa:
There is a huge jet streak moving along the Cold Front and Warm Front cloud band. The location of this jet streak is as
expected from the ideal case as it does not follow the cloud spiral; but there is some deviation from the ideal situation
in the location of the jet streak maximum which is already a bit downstream from the occlusion band.
Shear Vorticity 300 hPa:
The shear vorticity at 300 hPa, especially the thick line representing the zeroline, supports the concept that the jet axis follows the rear edge of the Cold and Warm Front bands. This is the expected configuration for a Cold Conveyor Belt Occlusion.
PVA 300 hPa:
There is a PVA maximum in the area of the CCB Occlusion cloud spiral. But the location of this PVA maximum deviates from
the ideal situation. The PVA maximum should be in the left exit region of a jet streak and consequently (in this case) in a
more western part of the cloud spiral. But such an ideal configuration can only be expected when the jet streak is rather
straight and consequently shear vorticity is the main source for the PVA. In this special case the jet streak deviates from
this straight form and shows a high degree of curvature which tears the position of PVA away from the expected classical
one.
TFP:
The TFP shows a very well developed Cold Front and also a smaller but existing branch in the Warm Front shield. This is as
it is expected in the ideal case. In addition, there is also a well developed branch of a TFP in the Occlusion part, a
situation which is not existing in every case of a CCB Occlusion.
Equivalent Thickness:
There is a distinct gradient in the thickness behind the Cold Front cloud band and within the Warm Front Shield. There is
also a ridge in the thickness contours whithin the Occlusion cloud band; however, the ridge is rather broad and seems to be shifted in relation to the spiral. This is not the ideal configuration expected in this conceptual model, but such a
deviation can be seen quite often. In this case there seems to be the start of a Backbent Occlusion. This would also be in accordance with the distinct TFP in the cloud spiral. This development at the “northern” part of the CCB Occlusion might be the reason for the deviation in all corresponding fields.
Temperature Advection 700 hPa:
The general distribution of CA and WA is according to the ideal configuration: there is the zeroline of TA within,
at least, the southern part of the Cold Front and WA within the northern part of the Cold Front, and especially in the area of the cloud spiral of the Occlusion; CA is in the cold air behind the frontal system. The only feature that deviates from an ideal configuration is the large area of WA in the cold air close to the center of the occlusion spiral. Such a situation is often seen.