Detached Warm Front - Cloud Structure In Satellite Images

by ZAMG


 
04 January 2005/00.00 UTC - Meteosat 8 IR 10.8 image
04 January 2005/00.00 UTC - Meteosat 8 WV6.2 image
The satellite image at 00.00 UTC shows the cloud band of a Cold Front, from the Azores across Ireland and Scotland where it changes over to the cloud shield of a Warm Front over south-western Norway. Downstream, from Sweden southward as far as Austria, the satellite image shows a grey cloud field of a Detached Warm Front, which is already separated from the Warm Front Shield. North of the Alps Barrage Cloud can be recognised as the mountain forms a natural barrier. A little to the east of the Alps in Slovenia the clouds seem to penetrate southward.

The IR image shows bright grey shades indicative of the initial stage of the life cycle, with the brightest grey shades in the centre and at the leading edge which is nearly in accordance with the description of the ideal situation. The sudden decrease of the pixel values along the leading edge fits with the superimposed jet at approximately 300 hPa. The boundary of white to dark grey characterizes the jet axis.

In the WV image the separation between WF shield and Detached Warm Front can be clearly seen. Greyer value pixels are all located over southern Norway, Denmark and eastern Germany. An interesting and dominant feature in the WV image is the black, dry stripe from central Sweden over the Baltic Sea into the Baltic States and then further south into Serbia. It is an indication of the anticyclonic circulation within an upper level ridge.

04 January 2005/12.00 UTC - Meteosat 8 IR 10.8 image
04 January 2005/12.00 UTC - Meteosat 8 WV 6.2 image
04 January 2005/12.00 UTC - MSG VIS 0.6 image
The whole system has moved rather north-east and the detached cloudiness moved south. As the Detached Warm Front is influenced by the orography of the Alps, intensive cloudiness on the windward side and high Lee Cloudiness on the lee side (south-east Austria) develops.
In the WV image the detached cloudiness is seen as grey indicating less moisture. The WV dark stripe on the anticyclonic side is still very much noticeable.

The IR loop shows the development of the Detached Warm Front. Special attention should be paid at the time when the Detached Warm Front hits the Alps. As it then wanders eastward, more cloudiness penetrates southward on the eastern edge of the Alps over Slovenia.

03 January 2005/18.00 UTC - Meteosat 8 IR 10.8 image
03 January 18.00 - 04 January 18.00 UTC hourly image Loop

Menu Of Detached Warm Front
Meteorological Physical Background