202308 - Rainfall - Slovenia

Status:Ongoing analysis Material from: Linus, David L., Ziga

1. Impact

From floodlist.com (https://floodlist.com/europe/slovenia-floods-august-2023):

""

According to Slovenia’s environmental agency ARSO, northern and central parts of the country recorded more than 200 mm of rain within 12 hours from 03 to 04 August 2023. This is more than these areas would normally see during the whole of August, ARSO said.

The rain caused multiple rivers to break their banks, including the Savinja River in Celje where around 4,000 people evacuated their homes.

""

2. Description of the event

The northern parts of Ljubljana (the airport?) received 201 mm from 3 Aug 06UTC to 4 Aug 06UTC, and almost all fell between 18UTC and 06UTC. One can note that the central city only got 23 mm. More than 100mm was also measured for all stations in northern Slovenia.

The plots below show analyses of MSLP and 6 hour rainfall from 1 August 00UTC to 6 August 00UTC, every 12th hour.

The plots below show analyses of z500 and T850 from 1 August to 6 August 00UTC, every 24 hour.

3. Predictability

3.1 Data assimilation

3.2 HRES

The plots below show 24-hour precipitation (3 August 06UTC - 4 August 06UTC) in observations (first plot) concatenated short forecasts (second plot) and o-suite HRES forecasts with different lead times. There was some hits of extreme precipitation (>100 mm) in the western part of Slovenia but did not extend to the east, as in observations.

3.3 ENS

The plots below shows EFI and SOT for 3-day precipitation (3 August 00UTC - 6 August 00UTC) from different initial dates. The reason to use 3-day EFI is that the event spent over 3 and 4 August.

The plots below shows EFI for 1-day integrated water vapour (IVT) 3 August from different initial dates. A very strong water vapour flux was present in the region and was well predicted in the medium-range.