On Thursday there is a risk of severe weather in large parts of Germany from violent thunderstorms to super cells with heavy rain, larger hail, hurricane gusts and isolated tornadoes are also possible.
Certain conditions must be met for thunderstorms to form. The air must be moist and unstable. This is how the characteristic cumulonimbus clouds form in the rising air. Supercells are a very special form of thunderstorm cells and are also known as mesocyclones. Due to the change in wind speed and direction with increasing altitude, also known as wind shear, the updraft portion of the cell begins to rotate and straighten.
In a supercell, the updraft and downdraft areas are spatially separated. This is a major reason why a supercell survives significantly longer than a normal thunderstorm cell, in which the updraft and downdraft are almost identical. As soon as a thunderstorm cell has matured and a downdraft area has also formed due to precipitation, this disrupts the updraft area and ultimately cuts off the thunderstorm from its warm air supply. Without an updraft area, a thunderstorm cell quickly collapses. In a supercell, areas of updraft and downdraft can coexist for several hours and the cell remains alive.
Supercells produce heavy precipitation in the form of heavy rain, sleet or hail and due to the falling precipitation also strong downdrafts, which can sometimes reach storm or hurricane strength. The latter are so-called falling gusts and can cause serious damage, similar to tornadoes. Tornadoes are also phenomena that occur much more frequently during supercells than during normal thunderstorm cells.
A small-scale low-pressure system is moving from France towards Germany with a lot of humid air and meets hot air masses there. Large areas with wind shear can be found this afternoon, especially over southern Germany, and thus offer supercells ideal conditions for the formation. But in the west and in the center of Germany, heavy thunderstorms and even supercells could form from the afternoon and bring with them the weather phenomena already mentioned. There is a risk of severe weather in large parts of Germany well into the night. Be sure to heed the current alerts today and be careful. Severe storms are life-threatening!