Mesoscale Discussion
Valid: Wed 19 Jul 2023 12:00 to Wed 19 Jul 2023 15:00 UTC
Issued: Wed 19 Jul 2023 11:52
Forecaster: PUCIK/GROENEMEIJER

*** Damaging wind gust and very large hail risk increasing in the next hours ***

Lightning detection data show an intensification of storms on the border of Italy, Slovenia and Austria. The storms were elevated in the past and are now moving into an environment characterized by dewpoints around 20 °C and temperatures of 28 – 31 °C between central Slovenia and N Croatia. As a result, the storms are becoming surface-based. As this happens they are expected to further intensify and develop into supercells with a risk of large or even very large (> 5 cm) hail that rapidly organize into a fast-moving convective system. This system should transition into a bow echo as it moves to Serbia, with an attendant risk of severe and extremely severe (> 32 m/s) wind gusts.

More storms are expected to develop across the Italian Alps between 13 and 15 UTC. Very high 3000 – 4000 J/kg of MLCAPE and strong low-level storm-relative inflow due to the 15-20 m/s 0-3 bulk shear will create an optimal environment for very large or even giant hail with diameters in the 5 - 10 cm range and possibly higher. In addition, intense downbursts may occur with gusts locally exceeding 32 m/s.