The statistical analysis of thunderstorm gales over Beijing-Tianjin-Hebei region

Based on the observation data of disaster and significant weather report, the thunderstorm gale in Beijing-Tianjin-Hebei region is analysed from multiple perspectives. Specifically combined with the MICAPS data, NCEP data, automatic station data and Doppler weather radar data, the weather conditions, types and characteristics of thunderstorm gale are discussed. Results are as follows. Thunderstorm gales are mainly recorded in the mountains northwest of Beijing, coastal areas and the northwest plateau, but less in the plains. They present an oscillation decreasing trend in nearly 30 years. Thunderstorm gales first begin in mid-March, end in early November, while they happen most frequently in late June. They are often appear in June and July, and diurnally reach their peak during 14 PM to 20 PM. The ten-day and monthly distribution characteristics of thunderstorm gales are associated with cold air activity and the location of south branch jet stream. Higher thermal and dynamic conditions are favorable to the development of the thunderstorm gales in May and September, while higher instability and energy conditions are conducive to them in June, July and August. Weather types resulting in thunderstorm gale are mostly northwestly flow pattern and low vortex pattern. The monthly distribution characteristics of different synoptic systems are related to cold air activity, the location of subtropical high, the location and intensity of south branch jet stream. The areas affected by thunderstorm gales are relevant to the scale and strength of the influencing system. Regional thunderstorm gales the most frequently occur in cold front and low vortex weather. Moreover, the stronger damaging wind is, the higher probability the cold front appears. The multi-cell storms most happen and squall line less appear in the event of thunderstorm gale. The scope of the gale is related to the intensity of the storm. Squall line and super-cell storm have the highest probability of occurence when thunderstorm gales happen. Furthermore, the stronger damaging wind is, the higher probability the squall line appears.