engleski

Correlating overshooting tops and severe weather

Overshooting convective cloud top (OT) is a dome-like protrusion above a cumulonimbus anvil, often penetrating into the lower stratosphere. It represents a very strong updraft. A single OT exists for less than 30 minutes and has a maximum diameter of ~15 km. According to some investigations, deep convective storms with OTs often produce hazardous weather conditions such as heavy rainfall, damaging winds, large hail, cloud-to-ground lightning and tornadoes. The OTs also generate gravity waves which can produce significant turbulence. These events can cause considerable property damages, influence everyday activities and even endanger the human lives. Relationship between the occurrence of the OTs and severe weather conditions over Central Europe is established. The OTs are detected from Meteosat 8 and 9 data, using a combination of brightness temperature difference of the water vapor and the infrared channel (6.2-10.8 μm), and of the ozone and the infrared channel (9.7-10.8 μm). This method includes the infrared brightness temperature and brightness temperature difference criteria. Locations and times of appearance of the OTs are compared with the occurrence of the strong wind and wind gusts measured by the automatic stations. Additionally, hailpad and raingauge measurements are used to determine the relationship between the occurrence of the OTs and severe weather conditions. Favorable synoptic conditions, i.e. dominant large-scale weather types and associated wind regimes are revealed for OT related severe weather episodes.

overshooting tops; severe weather; automatic station data

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