Severe weather warnings for Sofia Bulgaria: May - September 2010-2019

Severe weather monitoring and forecasting is the prime task of the National Meteorological Services according to World Meteorological Organization Guidelines (WMO). Since 2009 Bulgarian National Institute of Meteorology and Hydrology (NIMH) issues 48 h ahead severe weather warnings as a contribution to the European warning system (METEOALARM). A total of 243 days with warnings for heat, thunderstorms and intense rain were issued for Sofia, Bulgaria the period May-September 2010-2019. The monthly maximum for heat is 42 days in July, for thunderstorms is 26 days in June and for intense rain is 27 days in June. The yearly heat maximum of 21 days is in 2012 from which orange code warnings are 8 and yellow code warnings are 13. The yearly thunderstorm maximum of 16 days with both orange and yellow code warnings is in 2018 where one day is with orange code and 15 days are with yellow code warnings. The yearly rain maximum of 20 days with both orange and yellow code warnings is in the same year 2018. There were 3 days of orange code warnings for rain, and 17 days with yellow code warnings. Conducted is objective circulation classification which shows that the majority of heat warnings are associated with Anticyclonic and West flow circulation types. About 40% of thunderstorm warnings are of Cyclone type followed by 28.6% Cyclonic Directional types. For rain warnings, most of the days are with Cyclone type (46.2%) and Cyclonic Directional types (27.5%). Analysis of Global Navigation Satellite Systems (GNSS) derived Integrated Water Vapor (IWV), from the Bulgarian station in Sofia, shows consistently higher values for the days with METEOALARM warnings for heat, thunderstorm and rain.