The deep trough that will pass the Alpine region and northern Mediterranean will form a cutoff low over the region and produce torrential rainfall over the northern Mediterranean and parts of the Alps. We take a look at current model guidance.
Expect major torrential rainfall in parts of northeastern Italy, western Slovenia, southern Austria and northwestern Croatia (Istra & Kvarner). Various models agree on over 200 mm / 24-36h of rainfall locally, with some models suggesting values over 300 mm. Torrential convective rainfall, likely from slowly moving convective lines and training storm cells will combine with orographic rainfall along the Alpine and Dinaric flank. Expect local flash flooding.
The potential for severe thunderstorms is inconclusive at this time, as successive model runs change the trough tilt between negative and positive. Strong instability will be present, as moist air from the Mediterranean, particularly the northern Adriatic sea. MLCAPE in 2000-3000 J/kg range is expected. Thunderstorm severe potential will depend on the shear available: over 30 kt deep-layer shear will likely be available, expect multicell and potentially supercell thunderstorms. We will be taking a more detailed look at severe thunderstorm potential tomorrow.