Isotachs and PVA 300 hPa.

1st March 2004: 00UTC
There is a pronounced jet streak along the frontal cloud band but its axis are not along the rearward edge but within the cloud band. A reason for this could be found in the fact that in these very northern latitudes the height of 300 hPa does not represent the real jet axis, however it should then be expected even more to the north.

Apart from this question there is a quite pronounced PVA maximum at the cyclonic side in the area of the cloud development in the cold air. This PVA maximum can be related to the left exit region of the western jet steak maximum.

Consequently there is a clear relation between the development of the cloud system under consideration and a PVA maximum in high levels.

1st March 2004: 06UTC
For this point of time the same can be said as for 6 hours before. The PVA maximum even has intesified.

1st March 2004: 12UTC
The intensification of the PVA maximum in 300 hPa goes on. Also the relation between the PVA maximum and the cloud system which will develop into the synoptic scale spiral is like in an ideal case

1st March 2004: 18UTC
Again there is a perfect relation between the PVA maximum, the left exit regio of a jet streak and the cloud system under consideration.

As the cloud system is growing it becomes very clear now that the PVA maximum, where the highest contribution to upward motion can be identified, is superimposed on the lower cloud part of the growing comma system, on the comma tail.

2nd March 2004: 00UTC
The relation between PVA maximum, jet streak location and growing comma is the same as described before. The situation is very typical and an indication for further intensification and further development.

2nd March 2004: 06UTC
The relation between PVA maximum, jet streak location and growing frontal system is the same as described before. In this image the superposition of the PVA maximum on the cloud band which has lower tops is very obvious and can be regarded as an indication for a cloud intensification. Indeed, the images show growing cloud tops during this and the consecutive development.

2nd March 2004: 12UTC
The relation between PVA maximum, jet streak location and growing frontal system is the same as described before. In this image the superposition of the PVA maximum on the cloud band which has lower tops is very obvious and can be regarded as an indication for a cloud intensification. Indeed, the images show growing cloud tops during this and the consecutive development.

2nd March 2004: 18UTC
The relation between PVA maximum, jet streak location and growing frontal cloud band is the same as described before. Especially the brighter grey shades (colder cloud tops) of the cloud band represent the effect of the superimposed PVA maximum.

3rd March 2004: 00UTC
The relation between PVA maximum, jet streak location and growing frontal cloud band is the same as described before. Especially the brighter grey shades (colder cloud tops) of the cloud band represent the effect of the superimposed PVA maximum.