CUMULONIMBUS (Cb) AND MESOSCALE CONVECTIVE SYSTEM (MCS)

Common Remarks

Thunderstorms can be seen in the satellite imagery on three scales:

• Single Cell Storms
  which are often too small to be detected with Meteosat 8
• Multi Cell Storms
  which consist of several single cells in different stages of development
• Super Cell Storms
  which are huge single cell storms

Another term commonly used in satellite meteorology is the Mesoscale Convective System (MCS) which forms on a bigger scale and is described in this manual. MCS are usually multi cell storms, but sometimes can also have the appearance of super cell storms.

There are many definitions of MCS in literature. One frequently used definition is: A deep convective system which is considerably larger than an individual thunderstorm; it is often marked by an extensive middle-to-upper tropospheric stratiform anvil cloud several hundred kilometres wide. One special case of MCS is the so-called MCC (Mesoscale Convective Complex), which is a huge quasi-circular MCS that lasts about 10 hours. MCCs are frequent in many parts of the world as the US, South America, Africa, Western Pacific and India, but are relatively rare in Europe, where only an average of around 5 MCC form every warm season. In the chapters discussing convective weather features, conceptual models of two different scales will be studied:

• The small to mesoscale conceptual model of Cb and MCS itself - which cannot be verified with satellite images - contained in this chapter
• The synoptic to mesoscale conceptual model of a typical MCS environment with a high probability for thunderstorm development, discussed in the chapters about convective cloud features in typical synoptic environments

Satellite images are somewhat limited in their ability to detect thunderstorms: while Meteosat 8 images are limited by their spatial resolution, NOAA AVHRR images are limited by their time resolution. A very useful tool for the detection of all thunderstorm types is radar. Consequently a short chapter addressing this topic is introduced (see Key Parameters).

---