Mesoscale Discussion
Valid: Fri 08 Jun 2018 15:00 to Fri 08 Jun 2018 18:00 UTC
Issued: Fri 08 Jun 2018 15:14
Forecaster: PISTOTNIK

12z soundings from Zadar, Zagreb, Szeged, Budapest and Vienna showed CAPE between 1000 and 2500 J/kg and vertical wind shear of 15-20 m/s deep-layer (0-6 km) shear. Particularly striking is a mid-level wind maximum at 600 hPa. It can be speculated that synoptic lift is maximized in the left exit of this wind maximum, assisting in convective initiation.

... NW Croatia, Slovenia, SE Austria ...

A number of supercells has formed in the past few hours over NW Croatia and is heading into central and E Slovenia. Hailstones larger than 8 cm were recently reported under the strongest storm at the Croatian/Slovenian border. Other storms are just initiating over the SE Alps near Graz (Austria) and will probably quickly turn into supercells as well.
Large to giant hail must be expected with any of these storms and an isolated tornado is not ruled out. They will head northward, probably veering towards the NNE twards the higher CAPE reservoir later on. As soon as upscale growth sets in, the severe wind risk increases as well.

... E Croatia into N Bosnia-Herzegovina ...

2m temperatures/dewpoints up to 33/21°C indicate maximized CAPE in this area, possibly exceeding 4000 J/kg to the NE of a dryline-like boundary. A capping inversion and a lack of synoptic lift makes convective initiation more questionable here, but the area should be closely monitored as well!