Europe: Adverse weather forecast across much of Croatia, Hungary, and Slovenia through at least May 23

Thunderstorms and heavy rainfall are forecast across much of Croatia, Hungary, and Slovenia through at least May 23. Isolated storms are expected across the region May 20 before more intense storms impact the area May 21. Further thunderstorms are likely across much of the region May 22-23. Heavy rainfall, strong winds, lightning, and possible hail may accompany storms. Heavy downpours could trigger flooding in low-lying areas and landslides on unstable slopes. Strong winds may cause property damage and power outages.

As of May 20, the Croatia Meteorological and Hydrological Service (DHMZ) has issued yellow thunderstorm warnings (the lowest level on a three-tier scale) across Gospic, Karlovac, Knin, Osijek, and Zagreb regions May 20. Orange thunderstorm warnings have been issued for Osijek and Zagreb regions May 21, as well as yellow thunderstorm warnings across the rest of the country. Yellow strong wind warnings have been issued for Dubrovnik, Rijeka, and Split regions, as well as most coastal waters, May 21.

The Hungarian Meteorological Service has issued yellow heavy rainfall warnings for northern, north-central, and northeastern regions and yellow thunderstorm warnings across the country May 20. Orange thunderstorm warnings have been issued for Baranya, Somogy, Tolna, and Zala counties and yellow thunderstorm warnings are in place across the rest of the country May 21. Yellow heavy rainfall warnings have been issued for western regions May 21. Further yellow thunderstorm warnings are in place across Hungary May 22-23.

The Slovenia Environment Agency has issued yellow thunderstorm warnings for southeastern regions May 20. Orange thunderstorm warnings are in place for central, northeastern, and southeastern regions May 21, as well as yellow thunderstorm warnings for the rest of the country and yellow heavy rainfall warnings nationwide. Yellow thunderstorm warnings have been issued across Slovenia May 22-23.

Officials could update and possibly extend the coverage of weather alerts over the coming days.

Sustained heavy rainfall could trigger flooding in low-lying communities near rivers, streams, and creeks. Urban flooding is also possible in developed areas with easily overwhelmed stormwater drainage systems. Sites located downstream from large reservoirs or rivers may be subject to flash flooding after relatively short periods of intense rainfall. Landslides are possible in hilly or mountainous areas, especially where heavy rainfall has saturated the soil.

Authorities could issue mandatory evacuation orders for flood-prone communities over the coming days. Disruptions to electricity and telecommunications services are possible where significant flooding or landslides impact utility networks.

Floodwaters and debris flows may render some bridges, rail networks, or roadways impassable, impacting overland travel in and around affected areas. Ponding on road surfaces could cause hazardous driving conditions on regional highways. Authorities could temporarily close some low-lying routes that become inundated by floodwaters. Severe weather could also trigger flight delays and cancellations at airports in the region. Flooding could block regional rail lines; freight and passenger train delays and cancellations are possible in areas that see heavy rainfall and potential track inundation.

Localized business disruptions may occur in low-lying areas; some businesses might not operate at full capacity because of flood damage to facilities, possible evacuations, and some employees' inability to reach work sites.