Frontal System across Europe with Wave Development - Case Study 12 - 13 November 1997

• I. Synoptic Situation for 12 November 06.00 UTC
• Overview and frontal diagnosis
• Wave development in the area Sardinia - Corsica
• Intensification of frontal cloudiness and activity by jet streak crossing
• Cloudiness over Italy and the Balkan peninsula in front of the Cold Front: Relative Streams
• II. Development During the next 12 Hours
• Frontal displacement with help of the Thermal Front Parameter
• Displacement of the Wave
• Front Intensification by Jet Crossing
• III. Synoptic Situation for 12 November 12.00 UTC
• Overview and new aspects
• Diagnosis of front and Wave(s)
• Relative streams: Cloudiness over the Balkan peninsula
• IV. Synoptic Situation for 12 November 18.00 UTC
• Comparison of cloud configurations between 12.00 and 18.00 UTC
• Overall situation and frontal diagnosis
• Relative streams
• V. Synoptic Situation for 13 November 00.00 UTC
• Introduction for 13 November 00.00 UTC
• Overview and frontal situation
• Relative streams: Frontal and pre-frontal situation
• VI. Development of Thunderstorms and MCSs During the Whole Period
• Introduction for the diagnosis of conceptual modles for convective developments
• The period 12 November 05.00 - 07.00 UTC
• The period 12 November 11.00 - 12.00 UTC
• The period 12 November 14.00 - 18.30 UTC
• The period 12 November 21.00 UTC - 13 November 00.00 UTC
• Some summarizing ideas

Comparison of cloud configurations between 12.00 and 18.00 UTC

12 November 1997/12.00 UTC - Meteosat IR image	12 November 1997/12.00 UTC - Meteosat WV image
12 November 1997/18.00 UTC - Meteosat IR image	12 November 1997/18.00 UTC - Meteosat WV image

A comparison of the cloud configurations at 12.00 UTC (left and right image top) with those in the IR and WV imagery for 18.00 UTC (left and right image bottom) can be summarized into four topics:

• The Wave structure over the west Alps has moved northward without any further development of the spiral structure;
• The area of the Front Intensification by Jet Crossing has further intensified with a wave-like bulge recognizable between the Algerian coast and Sardinia and some very notable Cb developments between the Tunisian coast and south Sardinia. The latter do not only show the typical shape of Cb cells but also a dry zone around them representing sinking air; all thunderstorm events and their synoptic environment are discussed in a separate chapter (compare Development of Thunderstorms and MCSs During the Whole Period);
• The cloudiness in front of the frontal system over the Balkan Peninsula is still discernible and even more intensive, especially over east Slovenia and Croatia which indicates convective developments there;
• High fibrous cloudiness in band form has developed over Libya and has reached the Mediterranean coast.