Episode 25, 8 December 2020
Analysis
Description
Meteorological background
In the week leading up to the extreme sea level in Bakar, intense cyclones influenced Adriatic weather resulting in multiple episodes of strong Sirocco winds. On 6 December, a cyclone moved from western Europe to the northern Adriatic, causing heavy rain and strong southerly winds that weakened by day’s end. By 00:00 UTC on 8 December, a new low-pressure system formed over the Gulf of Lion, moving toward the Gulf of Genoa, inducing Sirocco (southeasterly wind) across the Adriatic, more intense along the eastern coast. These winds peaked in the northern and middle Adriatic before the occlusion front passed, while moderate Bora winds dominated in the Trieste Bay.
Sea-level evolution
On 8 December 2020 at 13:00 UTC, Bakar’s sea level rose to 92 cm above long-term average. The tide, influenced by the last quarter moon, had a diurnal neap-tide character and contributed -1 cm to the event. Cyclones earlier in the week generated basin-wide seiches (T~21.5 h), starting on 3 December and intensifying on 6 December when prolonged Sirocco winds shifted to northwesterly. The synoptic component, comprising a storm surge and pre-existing seiches, reached 41 cm during the main maximum, with pre-existing seiches amplifying the event by aligning positively with the storm surge.
The remaining sea-level rise resulted from processes acting on other time scales (refer to Figure 1 in the Introduction for detailed explanations). Local processes were negligible adding only 1 cm, long-period sea-level variability added 33 cm, and mean sea-level changes added 18 cm.
The episode resulted from the combined effects of large synoptic and long-period sea-level components, superimposed on mean sea-level changes, with minimal or negative contributions from local processes and tide.
Newspaper reports
Here are excerpts from reports about the flood from Jutarnji list.
Jutarnji list, 8 December 2020
THE SEA OVERFLOWS ON THE COAST, GALE-FORCE SIROCCO WIND, FLOODS IN VRGORAC
-Particularly difficult situation in the Vrgorac region, where 20 families are cut off from the rest of the world
The weather affected large parts of Croatia on Tuesday. In the Istria region, Istramet reported strong sirocco with stormy gusts, heavy rain and flooding. Due to the strong sirocco along the east coast of Istria, the sea is overflowing onto the quays, and the Istramet meteorological station in Labin near Fortica registered a gust of up to 131 km/h. Due to the high water, traffic is closed in Antenal at the mouth of the river Mirna, and there is heavy flooding throughout Istria and Kvarner. In Rovinj and Pula, the sea overflowed its banks and part of the town of Cres was flooded.
Chaos in the Vrgorac region
The Vrgorac region was hit by a severe storm, reports Slobodna Dalmacija. The residents of KokoriÄi near Vrgorac spent another sleepless night fighting the water coming from the swollen river Betina and the underground streams of Žilinja. The water level has risen by 45 centimeters since last night and, as frightened locals say, there is no end in sight to this ordeal as the water level continues to rise and meteorologists forecast more rain.
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āFive houses are currently under water and about twenty are completely cut off from the outside world. Some of my neighbors just had new kitchens installed and are now struggling to remove and save their furniture. Everyone is fighting in their own way to save what can be saved. Rabbit barriers are being built, bricks with “pur-foam” attached, plastic tarpaulinsā¦ But, nothing helps, because the water level is rising by the hour and threatens to flood two more houses. I would like to praise the members of the Croatian Mountain Rescue Service, who were with us all night, filling sandbags, bringing food and carrying furniture out of the houses. We also have the support of the “Vodoprivreda” workers, who have been in the village for several days and are working diligently on the flood protection front,” says Branimir Pervan, adding that the water depth next to his house is about 2.3 meters and he cannot leave his house without a small inflatable boat.