午夜欧美大片免费观看,欧美激情综合五月色丁香,亚洲日本在线视频观看,午夜精品福利在线

There was an extreme thunderstorm gale weather event that occurred in central Hebei Province on 24 July 2023, which was missed in forecasting. The maximum wind speed at 6 national observation stations broke the record for the maximum value or ranked in the top two, with the maximum wind speed being 30.6 m/s, which appeared at the Yuanshi station. The large-scale weather background of this event was the weak northwest wind at the upper air weather chart, and the weather system was not obvious, which led to the failure of forecasting the thunderstorm gale disaster in the middle and short-term weather forecast. Using ERA5 reanalysis data, dual-polarisation weather radar, wind profile radar, L-band radiosonde, minute-level ground encryption observation station data, and other multi-source high spatial and temporal resolution observation data, the evolution characteristics and causes of the extreme thunderstorm gale weather event are analysed. The results show that: (1) The process of thunderstorm wind belonged to the high-altitude dry and cold advection weak forcing type, and there was an unstable atmospheric junction of low-level warm and upper-altitude weak cold. The CAPE value was 1544.8 J/kg, SI was -4.31 ℃, and the temperature difference between 850 hPa and 500 hPa exceeded 30 ℃, with the vertical wind shears of 0-3 km and 0-6 km being moderate-to-slightly weak. (2) The wind speed of the single-peak and the first stage of the double-peak were characterised by strong sudden onset, large instantaneous wind speed, and short duration. The corresponding radar echoes of the convection system included three categories: storm cells, bow echoes, and gust front, which were characterised by Z_DR column, K_DP column, low C_C value, large wind core above 17 m/s, velocity ambiguity, and radial convergence of 3-8 km in the middle layer. The surface meteorological elements were thunderstorm high pressure with centre pressure above 1006 hPa and surface cold pool with temperature variations of one hour less than -3.5 ℃, corresponding to the steep rise of pressure, the sudden drop of temperature, the valley value of zero layer height, and weak precipitation. Compared with the first stage, the wind in the second stage of the double-peak type was significantly weaker, with a smaller impact range and a short duration, accompanied by no precipitation or only weak precipitation, corresponding to the weak radar echo type, which was caused by the regenerative weak echo after the main radar echo and the cold pool density current. (3) Extreme winds were also related to the new relocation station with few obstacles.