MSG IR10.8 imagery with extremely stretched temperature ranges: time sequence

9th June 2004: 0000UTC
With that special processing of IR-images fine structures can be investigated. In this sequence we investigate V-Notches. IR-temperature above -62°C and below -66°C are in red and blue, respectively. The temperature range in between is stretched extremly. The image from 00 UTC shows the super cell over the North Sea.

9th June 2004: 0030UTC
The super cell weakend during the last 30 minutes. However, it exhibits still cloud top temperatures similar to the tropopause temperature (-64°C).

9th June 2004: 0100UTC
In this image we find the indication of a V-Notch. In higher levels the wind came from western directions. The peak at the western parts of that area with the highest tops is directed against the west wind. Typicaly, at the western edge of the V-Notch very high extending clouds (colder than -66°C) and in southeastern direction warmer cloud tops (above -62°C) develope. That correspond well to the conceptual model of a V-Notch (Physical Background, Topic No. 5).

9th June 2004: 0130UTC
The patterns described for the image for 01 UTC is now more pronounced (55°N°E / 06°E).

9th June 2004: 0200UTC
At this time two areas of very low cloud top temperatures with relatively high cloud top temperatures southeast of the blue areas existed.

9th June 2004: 0230UTC
The V-Notch achieved the most pronounced form (see also link „Physical Background“, Topic 5). The peak of the blue area is directed against the West-Northwest wind. We find short extensions to the Northeast and Southwest and longer ones to the East and South. Southeast of that blue area much warmer cloud tops were detected (-60°C). That fits very well to the conceptual model. One theory is that this is a older overshooting extending still into the stratosphere. However, in the meanwhile it has got the temperature above the tropopause that is about -60°C (Relevant Radiosoundings).

9th June 2004: 0300UTC
The structure of the V-Notch dissolved.

9th June 2004: 0330UTC
Only a weak indication of a V-Notch can be recognised (8°E).

9th June 2004: 0400UTC
At the northwestern part of the relevant cloud structure we observe a reactivation and a indication of a V-form (blue area).

9th June 2004: 0430UTC
With exception of one pixel the whole complex exhibits cloud top temperatures above -66°C.

9th June 2004: 0500UTC
The super cell is passing the federal state „Schleswig-Holstein“ and Hamburg. However, no V-form can be found.

9th June 2004: 0530UTC
The super cell exhibits a ring-structure with relatively high temperatures in the centre and two small areas with low cloud top temperatures. The blue pixel just over the Elbe is connected to a new development whereas the blue pixel further to the Northwest is the decaying part of the super cell.

9th June 2004: 0600UTC
The new cell intensified and arrived Hamburg. We recognise the establishing of a V-Notch at the western edge of the super-cell.

9th June 2004: 0630UTC
The image reveals a relatively big blue area. That in combination to the two red coloured pixels gives a clear hint to a V-Notch yielding a high probabiliy of severe thunderstorms (hail, strong gusts). The displacement of the storm complex exhibits typically a deviation against the wind direction between 3 and 5 km by about 10 to 20° to the right.

9th June 2004: 0700UTC
The relatively big blue area splitted into several smaller ones. We recognise the pattern of relatively low cloud top temperatures at the western flank and higher cloud top temperatures southeast of it and at the „warmer site“ of the super cell.

9th June 2004: 0730UTC
The whole structure exhibits a big „V“ directed to the West. However, that does not fit well with the Northwest wind in upper levels. Another interpretation could be that we have a chain of two V-Notches. A smaller one is to be seen at the western peak with some red coloured pixels east of it. A bigger V-Notch could be in relation to the bigger blue area and relatively high cloud top temperatures South to East of it.

9th June 2004: 0800UTC
During the last 30 minutes the super cell weakened significantly.

9th June 2004: 0830UTC
The whole complex continued decaying during the last 30 minutes.

9th June 2004: 0900UTC
The intensity of the convection decreased. We do not find a pixel indicating cloud tops above the tropopause.