Analysis of the Causes of a Continuous Heavy Snowfall at Urumqi Airport
Using conventional sounding data,FNL reanalysis data(0.25°×0.25°)etc.,this paper analyzes the causes of a continuous heavy snowfall at Urumqi Airport during January 23-24,2021.The conclusions are as follows:1)The snowfall weather occurred in an environment under the combined effect of the southward pressure of the polar frontal zone and the splitting fluctuations of the mid-latitude trough.The continuous transport of mid-latitude moisture from the 700-500 hPa deep rapids region was the key to sustaining this snowfall for a long time.The convergence of two low-level rapids on the northern slopes of the Tien Shan and the interaction of the northerly rapids with the topography of the Tien Shan were responsible for the significant increase in precipitation on the northern slopes of the Tien Shan this time.2)The low-level inversion layer around Urumqi during the pre-snowfall period played a role in energy accumulation to a certain extent.The inversion temperature was broken by the cold air intrusion at low altitude,resulting in the enhancement of the slope pressure instability energy,which provided thermal conditions for snowfall weather.3)The configuration of low level convergence and high level dispersion provided favorable conditions for the development of upward motion,while the early upward motion in the low level as well as the late deep upward motion area provided favorable dynamic conditions for the continuation of this snowfall.4)The moisture of this snowfall was mainly transported from the mid-latitudes,the presence of 700-500 hPa polar frontal area and strong westerly and southwesterly wind rapids made the transport stable and continuous.Continued convergence of water vapor fluxes on the northern slopes of the Tien Shan allowed for long snowfall duration,eventually leading to the heavy snowfall.
Urumqi International Airportcontinuous heavy snowfallrapidsforced uplift of terrain
NETL
NSTL
万方数据
