Thunderstorm activity at high latitudes observed at manned WMO weather stations

Ongoing global warming particularly affects the coldest regions of our planet, where thunderstorm activity is considered to be the lowest. Scientific studies usually predict that lightning will become more frequent in polar areas in a warmer world. The aim of this study is to test this hypothesis and present the current knowledge on thunderstorm occurrence at high latitudes (>60 degrees) based on SYNOP data from manned WMO stations operating from 2000 to 2019. According to this source, most thunderstorm events at high latitudes occur in summer (85%), when the air temperature ranges from 15 to 25 degrees C (70%), during the days with positive temperature anomalies (75%) and negative sea-level pressure anomalies (65%). The highest thunderstorm activity is observed over inland areas, especially in the European part of Russia. The changes in thunderstorm frequency are only visible at certain WMO manned stations and mostly during the summer months. The regional Kendall test revealed a statistically significant increase in the number of thunderstorm days north of 60 degrees N in Interior Alaska, northwestern Canada, much of Siberia and European Russia. A decrease in thunderstorm frequency over a larger area was detected only on the shores of the southern Norwegian Sea, and seasonally in spring in the northern Urals. The observed trends were strongest in the Central Siberia and Interior Alaska regions, where the increase in the number of thunderstorm days exceeded 5 per decade. For the entire high-latitude area, the change in the number of days with thunderstorms was statistically insignificant, but for stations located 250-1,000 km from the coastline, the averaged increase amounted 1 day per decade.