Status: Finalised Material from: Linus, Ivan
1. Impact
On 27 July 2017 a high impact weather over Istanbul caused wind gusts of up to 40 m/s, ~9cm of hail and 55 mm total precipitation which caused fallen trees (311) and minarets (2), roofs dismantled (162) due to the high wind and plenty of dented cars and broken windows due to the large hail stones.
2. Description of the event
The plot below shows the satellite image from Meteosat channel 9 from 15UTC on 27 July and corresponding simulated satellite image from a 9 hour forecast.
European Severe Database (ESWD) reports and ATDnet lightning density valid for 27 July 2017 are shown below. There are 3 reports from Istanbul for heavy rain, large hail and damaging lightning.
3. Predictability
3.1 Data assimilation
3.2 HRES
The plots below show observed precipitation 27 July 06UTC to 28 July 06UTC and forecasts valid at the same time.
The plots below show forecasts of 24-hour maximum wind gusts for 27 July.
(Add observation plot)
3.3 ENS
EFI for CAPE-shear is shown below starting from T+156-180h to T+0-24h. All the forecasts are valid for 27 July 2017.
EFI for CAPE is shown below starting from T+156-180h to T+0-24h. All the forecasts are valid for 27 July 2017.
3.4 Monthly forecasts
3.5 Comparison with other centres
4. Experience from general performance/other cases
5. Good and bad aspects of the forecasts for the event
- Good medium-range signal in the CAPE EFI.
- Probably under-predicted the strength of the convection
- Missed the wind gust part of the convective event