Analysis of snowfall at Istanbul International Airport on 13–15 February 2021

In mid-February 2021, a cold air wave from the Balkans reached Istanbul, and the snowfall that occurred with this event negatively affected transportation and daily life in the city. This cold weather, combined with the humid air of the Black Sea, caused heavy snowfall in Istanbul. The snowfall caused traffic disruptions and delays in transportation; it also caused planes to land and divert. Therefore, in this study, we discuss whether this event was caused by sea-effect snowfall due to the increased intensity of snowfall at Istanbul International Airport from 13 to 15 February 2021. The reason for choosing this time period is that this snowfall event in Istanbul has not been examined in detail compared to other studies, so it has been thoroughly analysed in this study. This study was supported by the Grid Analysis and Display System (GrADS) software, which was used to analyse the geopotential height, temperature isotherms, relative humidity, wind direction and magnitude, and wind shear at the upper levels. The daily mean value of the obtained sea surface temperature was 9.15 °C, and the 850 hPa temperature was − 8.76 °C. The wind shear between the ground and 700 hPa level was at least 60 degrees. The wind speed exceeded 10 m/s on the days studied, and the wind changed direction from north-east to south-west on 13 February, 18:00 UTC, increasing the sea effect. According to the findings, the inversion height reached 800 hPa on 14 February and 700 hPa on 15 February; thus, the inversion continued, and the maximum inversion strength was 4.2 °C on 14 February. With the effect of the warm front coming from the Balkans and favourable synoptic conditions around Istanbul, snowfall occurred after 18:00 UTC on 13 February, and it was concluded that the precipitation on 14 February was in the form of heavy snow, resulting in sea-effect snowfall. Along with these results, radar and satellite images also show that there was sea-effect precipitation.