Europe: Adverse weather forecast across southern regions through at least Dec. 3 /update 2

Thunderstorms and heavy rain forecast across southern Europe through at least Dec. 3. Disruptions possible.

Event

Thunderstorms, heavy rain, strong winds, and possible flooding are forecast across Bosnia and Herzegovina, Croatia, Hungary, northwestern Greece, southern and central Italy, and San Marino through at least Dec. 3. As Dec. 2, authorities have issued the following warnings and watches across the affected area:

Orange heavy rainfall, thunderstorm, and strong wind warnings (second-highest level on a four-tier scale): Foca, Livno, Mostar, and Trebinje regions in Bosnia and Herzegovina; Knin, Gospic, and Rijeka regions in Croatia; Southern Transdanubia region in Hungary; Epirus and Ionian Islands regions in Greece; Abruzzo, Basilicata, Calabria, Campania, Lazio, Liguria, Molise, Sardinia, and Sicily regions in Italy.
Yellow thunderstorm, heavy rainfall, and strong wind warnings: the rest of the affected area.

Authorities will likely issue new alerts or update/rescind existing advisories as weather conditions change over the coming days.

Hazardous Conditions
The storms could produce rounds of heavy rainfall, strong winds, and isolated thunderstorm activity across the affected area. 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 the soil has become saturated by heavy rainfall. Power outages could occur throughout the affected area.

Transport
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. The disruptive weather may cause some delays and cancellations at regional airports. Authorities may temporarily suspend port operations if strong winds trigger hazardous sea conditions, impacting freight and passenger maritime traffic. Flooding could block regional rail lines; freight and passenger train delays and cancellations are possible in areas that see heavy rainfall and potential track blockages.

Disruptions triggered by inclement weather and resultant hazards, such as flooding, could persist well after conditions have improved - it could take days before any floodwaters recede and/or officials clear debris. If there is severe damage to infrastructure, repair or reconstruction efforts may result in residual disruptions.

Advice

Monitor local media for weather-related updates and advisories. Confirm all transport reservations. Stay away from elevated streams, creeks, and other watercourses that are prone to flash flooding. Do not attempt to navigate flooded roadways. Exercise caution in elevated terrain due to the threat of landslides. Charge battery-powered devices in the case of prolonged electricity outages.