Mesoscale Discussion
Valid: Mon 17 Aug 2020 15:00 to Mon 17 Aug 2020 19:00 UTC
Issued: Mon 17 Aug 2020 15:27
Forecaster: PUCIK

*** Threat of extremely heavy rainfall, as well as isolated large hail and severe wind gusts persists over the highlighted area ***

On the border of Slovakia and Hungary, amateur weather station has observed more than 180 mm of rainfall over the course of last two hours. Large hail has also been reported with a line of storms stretching from southern Slovakia into southeastern Austria.

New cells are initiated along the outflow boundary surging southeastwards, encountering southeasterly wind of 5 to 10 m/s. Thus, the whole complex of storms is forecast to propagate south and southeastwards in the next three hours. Surface observations show very moist airmass ahead of the storms with dewpoint values between 16 and 20 deg C. 12 UTC soundings from Budapest and Zagreb confirm presence of thermodynamic profile favourable for heavy rainfall with low LCLs and high values of PW. Zagreb also shows higher MLCAPE, up to 3000 J/kg, compared to 1000 J/kg of CAPE in Budapest profile. Therefore, it is possible that the large hail threat will increase as storms spread south. With 10 - 15 m/s of 0-3 km shear, most storms will remain multicellular, with tendency to backbuild towards south. Due to this fact, extremely heavy rainfall will continue to be the highest threat in the next couple of hours.