This morning’s water vapour satellite reveals an impressive upper low ejecting NE Spain. A lot of deep convection is ongoing around the core. The system is expected to rapidly move across the northern Mediterranean this afternoon and in the evening. Very intense lightning activity suggests the ongoing convective storms are likely severe!
A short-wave trough/low rapidly moves from NE Iberia across N Mediterranean today, providing a large scale forcing for organized convective activity.
Moderate to strong instability (1500-3000 J/kg of MLCAPE) combined with quite an impressive shear (40-70 knots) will be favorable for organized storms, including multicell and supercell storms. Given the large amount of ascent ahead of the trough, storms will likely grow upscale into clusters (MCS) while being pushed across north-central Italy and Adriatic sea into W Slovenia and NW Croatia. The primary threats will be severe damaging winds, large to very large hail and excessive rainfall. Some tornadic potential or waterspouts cannot be ruled out either.
Here are the GFS and HRRR model simulations of accumulated rainfall until midnight, locally high sums are likely, possibly reaching 75-100 mm. Flash floods are expected!
Storms / large clusters are expected to continue overnight while moving across the Adriatic sea onto the WNW Balkan peninsula.