Two large weather systems combined to produce some of Venice's worst flooding in decades. A large area of low pressure over the Mediterranean joined forces with high pressure over the Balkans (extending all the way into Russia) to push wind and water up the Adriatic Sea.
"The median level of the Adriatic Sea swelled to about 1.4 metres (1.5 yards) above normal - the highest in nearly two years - sending water from the lagoon into St. Mark's Square and many narrow alleyways," Reuters reported.
The converging atmospheric flow also produced torrential rains in parts of northern Italy.
"In Tuscany, 23 centimetres (9 inches) of rain fell in four hours, causing the Ricortola and Parmignola rivers to flood, according to the regional government," Reuters said.
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