Isotachs 300 hPa:
The jet streak reaching from South of Iceland eastward approaches the Split Front over the Norwegian Sea nearly
perpendicularly. This is very typical for a Split Front. In this case, the crossing of the jet streak happens rather far to
the north of the N-S oriented Split Front.
PVA 300 hPa:
The PVA max at 300 hPa is in the left exit region of the jet streak and is superimposed on the low part of the Split Front cloud band. The cloudiness in this area has a distinctly convective appearance. The relation to the jet streak as well as to the frontal cloud band is very typical.
Height of PV=2 units:
On the cyclonic side of the jet streak there is a clear sign of stratospheric air protruding down to 600 hPa or even lower. The jet axis is in the area where the height of PV =2 units is at about 300 hPa. This demonstrates clearly (and in accordance with the ideal case) that on the cyclonic side of the jet streak stratospheric air is overrunning the cloud band of the Split Front.
TFP:
In the ideal case a double structure of the TFP is indicated, representing surface and upper level front lines. In nearly in every real case such a differentiation is not so recognisable because the resolution of the ECMWF model is not
high enough. Also, in this case there is only the TFP at the rear side of the split front cloud band. The branch of the TFP over S. Norway is more related to the remnants of a Warm Front.
Equivalent Thickness:
Very typical is the thickness ridge in the higher cloud part at the leading edge and the thickness trough behind the Split
Front cloud band. In this case the model thickness isolines seem to be shifted to the West in comparison with the satellite
image. This would mean that the model is too slow.
Temperature Advection 700 hPa:
The field of TA shows similarities with the ideal situation but also several deviations. First of all the WA maximum in
the cold air to the rear of the frontal cloud band is unusual and a speciality of this case. Furthermore, in the ideal case a WA maxium is expected in the higher cloud band at the leading edge; in this case this only true for some parts of this area, while CA which should be restricted to the low part of the cloud band is spreading eastward. It is therefore not a very classical situation.
Relative Streams:
Relative streams on the isentropic surface 314K, system velocity: direction: 283, speed: 17 m/s.