mesocyklonen

Mesocyklonen, known in English as mesocyclones, are rotating updrafts within severe thunderstorms. They are a hallmark of many supercell storms and consist of an organized area of rotation in the rising air column, typically spanning several kilometers across and extending through a substantial portion of the storm’s depth. The presence of a mesocyclone is associated with enhanced tornadic potential and strong winds aloft.

Formation: In environments with strong vertical wind shear, a thunderstorm updraft tilts horizontal vorticity into the vertical, creating a localized rotating region within the storm. As the updraft intensifies, the rotation can become a persistent mesocyclone that may strengthen into a tornado under favorable conditions.

Detection: Mesocyclones are routinely identified with Doppler radar as a velocity couplet indicating rotation within the storm. Radar signatures such as a hook echo in reflectivity and a distinct rotational couplet are used to monitor potential tornadogenesis; visual indicators include a wall cloud and lowering features at the storm base.

Relation to tornadoes: Not all mesocyclones produce tornadoes, but most tornadoes in organized thunderstorm systems are associated with mesocyclones. Some mesocyclones dissipate without producing a tornado, while others intensify and produce one or more tornadoes.

Occurrence and duration: Mesocyklonen arise most often in warm-season convective outbreaks in regions with favorable shear. They can persist for tens of minutes to an hour or more, and their strength and longevity depend on environmental conditions and storm dynamics.

Significance: Mesocyklonen are a primary diagnostic feature for assessing severe weather potential, guiding warnings and forecasts for tornadoes and damaging winds.