Convective Storms RGB Time Sequence: 27 July 2006      

Because no images are available for 12 UTC we have to start the succeeding images from 12.15 UTC on.
The Severe Convection RGB, which is also discussed thoroughly in the MSG interpretation guide, is suitable for the detection of convection and enables us to discriminate between young and old convective cells.

The interpretation of the colours goes according to:

• Red: deep precipitating clouds containing large ice particle
• Yellow: Cbs with severe weather and strong updrafts; small ice particles or thick high level lee cloudiness.
• Dark red: thin cirrus; large ice particles
• Purple: thin cirrus cloud; small ice particles
• Blue: thin clouds or cloud free areas

With this RGB it is possible to perform more detailed diganostics. An important information in addition to the colour are the areas' shape and its position in relation to the airmass distribution. A convective cell with high potential for intensification exhibits a rounded shape. If the position of the yellow spot is at the "warm edge" of a cell we have to expect a higher probability for cell intensification.
According to these rules, in this sub-chapter "candidates" for intense convection will be identified and monitored in the succeeding images. We will mainly concentrate to the region indicated by the white rectangular. The images will be shown in 30-minutes intervals. If suitable the time increment will be reduced to 15 minutes.

Note: You can always click on the in the header to bring up the RGB-key.

During the last 15 minutes new cells developed and some increased. When we consider the zoomed image we identify two "candidates" for intensification over western Germany. Due to the lined shape of the cell over southwestern Germany we do not have to expect severe convection in this area.

The zoomed image shows clearly that the cell intensification continued. The two candidates enlarged. However, the cell on the left side of the zoomed image showes a round shaped yellow spot that is a clear hint on possible intensification.
When we compare the convective cell in the centre of the zoomed image an advantage of this RGB in comparison to the IR-enhanced becomes apparent. While the latter exhibits only a bigger area of cloud top temperatures below -64°C, the RGB contains information about existing small and big ice particles. Thus, the forecaster will be able to concentrate upon the most relevant parts of the cell complexes. The cell to the Southwest indicates also some potential for heavy convection in form of a round-shaped yellow spot. Although this can be seen in the corresponding IR-image (a few pixels with cloud top temperatures below -64°C) it is revealed better by the "Severe Convection" RGB.

The marked cell has intensified during the last 15 minutes in accordance to the rule "round sharp yellow spot". It is likely that this intensification will continue.

As expected the cell itensified. However, in the meanwhile the yellow area at the southeastern edge shows a rather big area without a spot. Therefore, a further intensification is not likely.
In the southern part of the zoomed image we see a new yellow and round spot. The forecaster should monitor this cell most carefully.

We consider the two marked cells. While the northern cell did not change significantly the southern cell kept growing. However, it seems that the maximum intensity was between 13.30 and 13.45 UTC.

The entire convective complex has passed over the maximum intensity. We still see a big complex of convective cells and some yellow coloured areas. However, rounded and small yellow spots cannot be observed anymore.

The general situation did not change significantly. We still observe a big complex of convection and some small spots in orange-yellow which indicate centres of more intensive convection.

The convection continued and the entire system moved slowly to the East. Locally new cells developed which can be recognized in form of yellow spots.

We still observe convection. However, the part with only thin cirrus clouds (purple coloured areas) growed. That means that the intensity of the entire convective complex decreased.

The weakening continues and only a few convective cells can be observed.

The mostern part of the clouds are in relation to cirrus with small and larger ice particles and with deep precipitating clouds containing large ice-particles. Very seldom we find yellowish areas with strong updraft and severe weather.

The dissipation continues. Almost no yellow areas can be observed.

The convective complex moved to the eastern parts of Germany and continued weakening.

Due to the low sun angle at this time step the RGB "Convective storms" is of limited use because solar radiation is crucial for this RGB.

Only cirrus clouds can be recognized. Again, the usage of this RGB is not recommended during low altitude of the sun.