EUMeTrain: Nowcasting CAL Module - Basic Nowcasting

This is a three hourly sequence of enhanced IR images from 17 May 06/21 UTC till 19 May 06/06UTC. Enhancement of IR images means that groups of greyshades (cloud top temperatures) are coloured in special colours to enhance the visibility of cold/warm clouds. This is something completely different to the well known RGB images which are also coloured, but RGBs are combinations of different channels and the colours represent a combination of physical qualities of the different channels.

London (21 - 03)

At the beginning of the sequence London is already close to the rearward edge of the cold front cloud band. If you look at the images at 21 and 00 try to answer the following question.

Will London "leave" the frontal cloud band and get to the rear side till 03?

• Yes, this is very apparent
• No, it will stay within the thick part of cloud band
• It will be very close to or immediately at the rearward edge
• No, the frontal cloudiness will increase

Paris (00 - 09)

Over Paris the easternmost clouds of the cold front cloud band just have arrived. Look into the sequence of images from 00 to 06.

Can you find a firm answer to the following question: will Paris "leave" the frontal cloud band at 09 and get to the rear side?

• Yes, this is very apparent
• No, it will stay within the thick part of cloud band
• It will be very close to or immediately at the rearward edge
• No, the frontal cloudiness will decrease

Munich (09 - 18)

At 09, Munic has already been crossed by several cloud systems which are in the thickness ridge in front of the cold front. It is close to the cloudiness of the cold front cloud band. If you look at the sequence of images from 09 to 15 can you answer the following questions?

Munic will get under influence of cloudiness of which part (conceptual model) of the frontal system:

• It will remain in the cloudiness of the thickness ridge
• It will move into the cloudiness of the cold front
• It will move into the rear side of the frontal cloud band

The movement of the frontal cloud band is clearly retarded. Can you find reasons for this from the sequence of images?

• The retardation is connected to the arrival of the front at the Alpine mountains
• Between 09 and 18 a wave-like cloud bulge develops and moves from France into Germany. Wave development are responsible for a retardation of a frontal cloud band
• There is no reason for this seen in the sequence of imagey

Vienna (18/12 - 19/06)

In Vienna the cloud patches within the thickness ridge in front of the cold front cloud band have arrived a bit before 12.

If you look at the sequence of images from 12 to 18 can you answer the following questions? Under which cloud system of the frontal system will Vienna stay at 00?

• Still within the pre-frontal cloudiness in the thickness ridge
• Within the cloudiness of the cold front band
• At the rear side

If you look into the images from 00 on can you answer the following questions? Is there a wave development at the cold front band and if yes, will it further develop?

• No, the cloud bulge at the rear side has completely vanished
• Yes, there is a cloud bulge over Germany and Austria and it shows signs of development during the phase under inspection

If you follow now the sequence form 00 to 03, can you answer the following nowcasting question? Vienna will leave the cloudiness of the cold front band till 06 and move into the rear side?

• Yes; the movement is rather quick now
• No; the wave development retards the system and Vienna stays in the thickness ridge

Budapest (18/18 - 19/06)

At 18, the first clouds of the warm sector with rather warm cloud tops reached Budapest.

If you observe the sequence from 18 to 00 can you answer the following Nowcasting question? Will Budapest get under the influence of the cloudiness of the cold front cloud band till 06?

• No; the frontal system has slowed down since several hours; therefore it will remain in the thickness ridge
• Yes; from the eastward movement of the frontal system such a movment can be expected