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Baroclinic disturbance; heavy rainfall; flooding; Red Sea Trough; Rossby wave; UAE
Abstract:
This work examines a severe weather event caused by a baroclinic disturbance with heavy rainfall and thunderstorms, which struck parts of the UAE and caused major flooding on November 17, 2023. A low-pressure trough extending from the Red Sea Trough (RST) towards the Eastern Mediterranean (EM) led to extreme flooding. The unique intensity of this heavy rainfall was correlated to mid-latitude disturbance amplification even in the middle and upper tropospheric produced by RST. During the rain event, two intense moisture sources were injected into the region: one from the Indian Ocean, carried by southeasterly near-surface winds at 10m, and the other from the Red Sea and Equatorial Africa, transported at a mid-tropospheric level. A significant temperature gradient with ~8 °C difference in surface temperatures, particularly between the northern areas in contrast with the southern regions, and the wind shear formation over the northern parts of the study area initiated the baroclinicity structure in the borderlines of the cold front and thunderstorms. The findings also revealed an abnormal westerly jet stream intensification at 200 hPa, associated with a negative meridional wind anomaly, signaling the stretching of a Rossby wave over the study area during the heavy rainfall and flooding.
