BiH, Montenegro: Adverse weather forecast across both countries through at least Sept. 14

Severe weather is forecast across Bosnia and Herzegovina and Montenegro through at least Sept. 14. Heavy rainfall and thunderstorms are forecast across the region over the coming days, with some snow possible over mountainous areas. Storms may be accompanied by strong wind gusts, lightning, and hail. Heavy downpours may trigger flooding in low-lying areas, and strong winds may cause property damage and power outages.

As of Sept. 12, meteorological officials in Bosnia have issued red heavy rainfall warnings (the highest level on a three-tier scale) over Trebinje Region and orange heavy rainfall warnings over Banja Luka, Bihac, Foca, Livno, Mostar, Prijedor, Sarajevo, and Tuzla regions. Yellow thunderstorm warnings have been issued for Mostar Region, and yellow strong wind warnings are in place across Banja Luka, Bihac, Foca, Livno, Mostar, Prijedor, Sarajevo, Trebinje, and Mostar regions.

Montenegro's Institute for Hydrometeorology and Seismology (ZHMS) has issued orange heavy rainfall and strong wind warnings and yellow thunderstorm and rough seas warnings for the Adriatic coast region Sept. 12, as well as yellow rainfall warnings for the Central region and yellow strong wind warnings across the Central and Continental and Mountains regions. Red heavy rainfall warnings are in place for the Adriatic coast region and orange heavy rainfall warnings for the Central and Continental and Mountains regions Sept. 13, as well as orange strong wind and yellow thunderstorm warnings across the country and yellow rough sea warnings for the Adriatic coast region. Officials could update and possibly extend the coverage of the weather alerts over the coming hours and 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.