Two Severe Local Storms as Observed in the Arid Area of Northwest China

During the observation period of the project HEIFE, two severe storms were observed. The structure of these storms in the arid area are analyzed. The scales of the two storms were different from each other. One was of the order of 10 km and the other of the order of 100 km; however both storms were characterised by a strong downdraft within the well developed convective cloud: a squall line and a single cumulonimbus cloud, respectively. In the squall line case, strong winds with uniform wind direction continued for about three hours, which was caused by the widening of the squall line. In the case of the single cumulonimbus cloud, the wind field was divergent owing to the downdraft at the surface. These severe storms are similar phenomena in nature to those observed all over the world.