A case study of snowstorm gusts and blowing/drifting snow

Abstract

The mechanisms of strong winds associated with snow clouds, and the relationship between strong winds and blowing/drifting snow, were investigated. A snowstorm occurred with a typical L-mode snow band which was generated and organized longitudinally during a continental cold-air outbreak over the Sea of Japan. Doppler radar observations revealed that the snow band consisted of small echo cells arranged along the direction of the snow band. When one of the echo cells passed, blowing/drifting snow was generated and intensified by a snow cloud-induced gust, and the horizontal visibility near the ground surface was significantly decreased. Doppler radar and radiosonde data showed that the gust was due to the cold air outflow (CAO) from the snow clouds. The leading edge of the CAO was about 9 km ahead of the center of the snow cloud and the depth of the CAO was about 600 m near the forward flank of the snow cloud. The CAO was caused by a downdraft at the center of the snow cloud, which was initiated at a height of about 1.3 km and with a velocity in excess of 1 ms−1. The observed CAO speed was explained by the theory of the gravity current.

Dual-Doppler Radar Observations on Factors Causing Differences in the Structure of Snow Clouds during Winter Monsoon Surges

“…Loading and evaporation cooling are known to be general factors that initiate a downdraft in deep thunderstorms (Houze 1993). The importance of the loading and (or) the evaporation, has also been pointed out in other studies on convective snow clouds based on Doppler-radar observations (Sakakibara et al 1988b;Ishihara et al 1989;Maki et al 1992;Satoh 1994;Yamada et al 1994;Yamada et al 1996;Yamada et al 1997;Fujiyoshi et al 1998). Studies based on microphysical retrieval (Sun 1999), and on numerical simulation (Ikawa et al 1987), also suggested the importance of loading and evaporation in snow clouds.…”