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Synoptic-scale forecast (see the figure above) about the cyclogenesis seems to be good in the HRES.
Looking at the HRES we see that the instability over the country is quite high. CAPE in the forecast initialised at 00UTC on the day of the event exceeded 2500 J/kg in south-eastern parts of the country. Unfortunately maximum values of CAPE were not particularly high over the most affected region around Varna where a quasi-stationary convective cell developed producing huge amounts of rain just in few hours. This can explain why the model underestimated the rainfall totals in that region. Another important remark is related to the frequency of the model output: maximum CAPE during the period is significantly higher in case of hourly model output compared to the operational 3-hourly output.
Maximum CAPE during the specified period is shown as well as maximum CAPE in case the convective inhibition (CIN) is less than 200 J/kg and therefore convection can be triggered. When CIN is greater than 200 j/kg the cap is so strong that it prevents convection from happening.
3.3 ENS
The flash floods occurred on 19 June in the evening and in early morning on the 20 June when just in few hours more than 100 mm of rainfall were recorded in NE part of the country. Flash floods occurred there. The analyses show that 99th model climate percentile for 24h total rainfall was exceeded in many places in the east of Bulgaria. Some local heavy showers were observed in some far western regions of the country as well. If we compare observations with the 95th model climate (M-climate) percentile, we'll notice areas of local torrential downpours in many parts of Northern Bulgaria as well. The shortest range EFI forecast matches quite well the areas affected by heavy rain but the EFI has never reached extremely high values close to 1 over NE Bulgaria. This could be due to the convective nature of the rain and the large uncertainty in the forecast that we might expect in such cases. Note that there is 6-hour shift between the validity of the EFI forecast and the accumulations represented by the observations: EFI is valid from 00 to 00UTC whilst accumulations are for periods of different length starting from 06UTC.
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