15 May 2004: 00 UTC

The backward inclined isolines of the equivalent potential temperature (black solid lines) show a position of the frontal zone. High pixel values (orange solid lines) in the satellite image in front of the frontal zone are connected with frontal cloudiness.

Isotachs (wind speed)

Above the crowding zone of the equivalent potential temperature the isotach maximum (yellow solid lines) is situated with a maximum at 450 hPa level.

Vorticity Advection

A maximum of PVA at 300 hPa is superimposed on the cloud system and represents the PVA in the left exit region of the jet streak. Between the two PVA maxima there is a NVA which is connected to the cloudless region (lower pixel values in the satellite image). Theoretical background of the connection between PVA and cloud development can be found in Manual of Synoptic Satellite Meteorology in the chapter BASICS.

Omega

The area of the maximum of PVA is an area of upward motion (negative values of omega). The main rising happens in connection within the convergence cloudiness.

Potential Vorticity

Potential vorticity shows an anomaly protruding deep down into the atmosphere, within or to the rear of the frontal zone. At this point in time PV=1 is on the rear side of the zone of the highest gradient of isentopes of the cold front, at about 750 hPa. More about the theoretical background of PV can be found in Manual of Synoptic Satellite Meteorology in the chapter BASICS.

Temperature Advection

The warm advection (WA) from the ground up to 200 hPa level can be seen and is connected to the cloud band of the frontal zone. Behind the frontal zone cold advection (CA) can be seen also through the whole layer.