The orographic modification of a precipitating convective cloud, which formed in association with typhoon 9304 and travelled over the sea, was studied by mainly analyzing the dual-Doppler radar system observational data. From July 24 1900 LST, to July 250000 LST, many connective clouds landed at the southeastern coast of the Kui Peninsula. Although they reached the coast in various stages of development, most of them showed similar features. Their radar-echoes were intensified 10 to 20km off the coast before landing, and the radar-echoes were intensified again or broadened over land after their radar-echo intensities were reduced near the coast. Before the first intensification of convective radar-echoes over the sea, the echoes were intensified in their upper rear-parts 30 to 40km off the coast, and intensified in their front-parts near the coast. By averaging horizontal winds derived from the dual-Doppler radar system observational data for about two hours, it was shown that the ambient wind speed decreased near the coast, and the horizontal convergence zone larger than 10-4 s-1 existed along the coast line about 10km off the coast. On the basis of these observational results the travelling convective clouds orographic modification, and the efficient formation of precipitation in them were discussed, taking into account the results of numerical experiment about the Kui Peninsula orographic effect on ambient winds. It can be inferred that the large rainfall amount recorded in association with the typhoon around the Kui Peninsula coast was caused as a result of the integration of travelling convective clouds orographic modification.
Two longitudinal-mode snowbands (bands I and II) were observed over the Ishikari Bay, Hokkaido, Japan during a wintertime cold-air outbreak. The three-dimensional kinematic structure of a snowband (band II) was examined in detail using dual-Doppler radar data. Band II noticeably developed over the Ishikari Bay. A high-reflectivity (approximately 35 dBZ at the maximum) zone was formed along the band axis and characterized the radar-echo structure of band II. The high-reflectivity zone of band II had the airflow structure dominated by circulations in vertical cross sections perpendicular to the band axis.The interactions between the two snowbands were discussed. Interestingly, it was found that radarecho bridges existed at the low levels between the two snowbands. The radar-echo bridges were formed in association with low-level outflows from the meso-y-scale convective cloud systems composing band I. The low-level outflows moved toward band II with time and penetrated into band II. This caused strong low-level convergence and the enhancement of updrafts in band II. Consequently, stronger radar-echoes were formed in band II and band II rapidly developed. Ice/snow particles were transported from band I into band II by the low-level outflows. It was considered that the rapid growth of these particles in the enhanced updrafts in band II would have contributed to the rapid development of band II.
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