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The figures above show the modelled flow for river Sava, close to Beograd. The peak flow appear around 18-19 May, with a flow of 6500-7000 m3/s in the EFAS system (corresponding to ~500 years return period). Already the longest forecast covering this date (9 May) had a number of ensemble members with return period >20 years. After the rain fell 14-15 May the uncertainty got minimal (as the flood model for the initial conditions is driven by observed precipitation). 
The hydrological part of the event is described on http://hepex.irstea.fr/balkans-worst-floods-for-more-than-100-years/
4. Experience from general performance/other cases
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