Climatology, Trends, and Atmospheric Environmental Controls of Thunderstorm Days in Türkiye Based on 24-Hour METAR Observations (2005–2025)

OpenAlex Türkçe

his study examines the climatology, trends, and atmospheric environmental controls of thunderstorm days (TSDs) in Türkiye during 2005–2025 using 23 METAR stations with continuous 24-hour observations. TSD series derived from hourly reports were analysed at monthly, seasonal, annual, and diurnal scales. Trends were assessed with the Hamed-Rao modified Mann-Kendall test and Sen’s slope, with false discovery rate correction and homogeneity tests used to evaluate robustness. Relationships between TSD and environmental variables from ERA5 and ERA5-Land were examined using Spearman correlation and multiple regression. Results show that Türkiye does not exhibit a single thunderstorm regime. Inland and high-elevation stations are characterized by a late- spring to early-summer maximum, whereas parts of the southern and southwestern coasts experience a longer convective season extending into the cold half of the year. Thunderstorm observations are predominantly daytime events nationally, but nighttime activity is relatively more important at coastal stations. Trend results are spatially heterogeneous; after multiple-testing correction, only the annual increase at Ankara remains statistically robust. Environmental analyses indicate that the K-index and convective precipitation explain interannual TSD variability more consistently than CAPE, while surface warming alone does not account for observed changes. Overall, the study provides a statistically cautious framework for understanding thunderstorm climatology in Türkiye.