A disturbance in the mid or upper part of the atmosphere which induces upward motion ahead of it. If other conditions are favorable, the upward motion can contribute to thunderstorm development ahead of a shortwave.
SHORTWAVE (OR SHORTWAVE TROUGH)
Meaning of SHORTWAVE (OR SHORTWAVE TROUGH) in English
A comprehensive English glossary of weather. Полный английский глоссарий погоды. 2012