Greece, Bulgaria: Weather warnings issued for northern Greece and southern Bulgaria, April 21

Officials have issued orange thunderstorm warnings for parts of northern Greece and southern Bulgaria on April 21. The warnings cover the Greek regions of Central Macedonia and East Macedonia and the Bulgarian provinces of Blagoevgrad and Smolyan. Authorities will likely issue new alerts or update/rescind existing advisories as weather conditions change 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 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 rain 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 could render some bridges or roadways impassable, impacting overland travel in and around affected areas. Ponding on road surfaces could cause hazardous driving conditions on regional highways. Authorities may temporarily close some low-lying routes that become inundated by floodwaters. Flight delays and cancellations at airports are possible. Authorities may temporarily suspend port operations or close beach fronts along the east coast if strong winds trigger hazardous sea conditions.

Localized business disruptions are possible 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.