Potential Vorticity at 300 hPa

At the rear side of the front a dark area connected to cold dry sinking air is recognised. Over the dark stripe the maximum of PV value of 2 units can be observed. The second darker area overlayed with PV value of 3 units is located far to the east.

The  situation similar to one 6 hours before.

The  situation similar to one 6 hours before.

Behind the frontal zone, over Romania and further to the north-west, the protruding stratospheric air can be recognized in the WV 6,2 µm image and confirmed by the modelled potential vorticity field. Behind the front, the model field fits well with the WV dark stripe. It's also the case over eastern Turkey where the PV value of 3 units is corresponds with the upper level low.

At this time step, the PV anomaly correlates well with a darker area over Romania where PV value has reached 6 units. In theory, the greater the number of PV units is, the deeper dry, stratospheric air is expected to penetrate into the atmosphere.

The maximum of potential vorticity at 300 hPa is found behind the frontal zone and fits well with the dark stripe in the WV 6.2 µm satellite image.

There is still very good coincidence between the PV maximum (PV value is 8 units) and the dark stripe behind the front.

There is still very good coincidence between the PV maximum (PV value is 8 units) and the dark stripe behind the front.