Europe: Storms to bring daily rounds of rain and snow to Balkan region Dec. 25-29

Event

Consecutive slow-moving low-pressure systems will bring rounds of rain and snow to much of the Europe's Balkan region through Dec. 29. The affected areas include central Austria, Italy, San Marino, the Vatican, Albania, Montenegro, Bosnia-Herzegovina, Croatia, Slovenia, southwestern Hungary, central Romania, Kosovo, North Macedonia, and western Greece. Forecast models indicate intense bands of rain and snow will develop and spread across the Balkan region, Italy, and Austria through Dec. 27. There will likely be a lull in the precipitation in Italy, Austria, and the northern Balkan region Dec. 27 before more rain and snow develop Dec. 28; this second round of precipitation is associated with Storm Bella in northwestern Europe. Rain and snow will likely persist in the region through at least Dec. 29.

Government Advisories
As of Dec. 25, authorities in Italy have issued orange-level warnings - the second-highest on a four-tiered scale - for northern and western regions due to strong winds, snow, and thunderstorms. Authorities in Montenegro have issued red-level warnings - the highest level on a four-tiered scale - for snowfall in the northern portion of the country, while red-level warnings for strong winds are in effect for northern Croatia. Orange-level warnings are also in effect in southern Montenegro for heavy rain and storms. Meanwhile, yellow-level warnings are in effect for the rest of the Balkan region over the coming days due to strong winds, snow, heavy rain, and storms Authorities will likely expand coverage of the advisories as the systems approach and weather conditions change over the coming days.

Hazardous Conditions
Forecast models indicate snowfall totals of 30-60 cm (12-24 inches) are expected in the Alps region, as well as in higher elevations of the Balkan region, especially in Croatia, Bosnia-Herzegovina, and Montenegro. Meanwhile, rainfall totals of 5-13 cm (2-5 inches) are expected in the hardest-hit areas over the coming days including the lower elevations of Balkan region, central Italy, western Greece, and central Romania. Slightly lower rainfall totals of 2.5-7.5 cm (1-3 inches) are forecast in eastern Italy and southwestern Hungary.

Flash and areal flooding is possible, especially in areas where the soil is saturated from previous storm systems. Such flooding could occur in low-lying communities near watercourses and other bodies of water, as well as in urban areas with easily overwhelmed stormwater drainage systems. Sites located downstream of large reservoirs may be subject to flash flooding after relatively short periods of intense rainfall. Where precipitation falls as snow, wind gusts could cause blowing and drifting snow; decreased visibility is likely in mountainous areas. Rain-induced landslides cannot be discounted in areas of elevated terrain; there is also the possibility of avalanches in mountainous areas where the snowpack has become unstable due to heavy snowfall. The adverse weather conditions could cause power outages throughout the affected area through at least Dec. 6.

Transport
Floodwaters and related debris may render some bridges, rail networks, or roadways impassable, impacting overland travel in and around the affected area. Flooding in urban areas could also result in significant traffic congestion. Heavy snow will likely make driving hazardous in some areas; authorities could implement temporary road closures or detours in such locations. Authorities could close mountain passes and tunnels as a precautionary measure during periods of intense snowfall.

The disruptive weather will likely cause some delays and cancellations at regional airports, including those serving Rome (FCO, CIA), Venice (VCE), Zagreb (ZAG), Sarajevo (SJJ). Authorities may temporarily suspend port operations if strong winds trigger hazardous sea conditions, impacting freight and passenger maritime traffic in the Atlantic Ocean, Bay of Biscay, and English Channel, as well as the North, Irish, Mediterranean, Balearic, Adriatic, Ionian, and Tyrrhenian seas. 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 debris is cleared. 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 and business arrangements prior to travel in the affected area through at least Dec. 29. Seek updated information on road conditions before driving or routing shipments through areas where severe weather is forecast; plan for possible supply chain disruptions if routing shipments through affected areas. 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, as well as mountainous regions where avalanches pose a threat. Charge battery-powered devices in case prolonged electricity outages occur.

Resources

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