Height of PV=2

30th July 2005: 06UTC
The frontal system and its substructures are clearly seen in WV6.2 imagery. On the rear of the front a darker area is recognised which is well reflected by the height of PV=2 with deepening of up to 500 hPa. On the leading edge of the frontal system a second area with deepening is observed over the Ukraine. Deepening to 300 hPa is accomapnied by two convective system that develop on the tip of this WV dark area.

The most interesting to this case is however found over Italy and Austria. This is the region where a few hours later the prefrontal convergence is starting. The area is already appears darker in this WV imagery and is marked by two seperate PV maxima.

30th July 2005: 12UTC
The frontal system and its substructures are clearly seen in WV6.2 imagery. On the rear of the front a darker area is recognised which is well reflected by the height of PV=2 with deepening of up to 500 hPa. On the leading edge of the frontal system a second area with deepening is observed over the Ukraine. Deepening to 300 hPa is accomapnied by two convective system that develop on the tip of this WV dark area.

Over Italy, Austria and further north into the Czech Republic and Poland a dark stripe is seen in WV imagery. This is the area where the prefrontal convection is about to start. The PV-fields mark the area with several maxima indication protruding stratospheric air.

30th July 2005: 18UTC
A prefrontal convergence line has formed. The convective cells have developed on the flanks of WV features, which appear darker in the image. The PV maxima are mostly found ahead of this line.

31st July 2005: 00UTC
The prefrontal convergence has partially dissolved and shifted towards the cold front part which level of convection has enhanced quite intensely. Within the cold frontal band still a PV maxima is seen over Belarus.

31st July 2005: 06UTC
Two MCSs are still observed over Poland and Russia. This latter convective system has already partially dissolved over night. In between a WV dark stripe is seen that is marked in the model by a PV maxima.