Valid: Mon 01 Jun 2020 06:00 to Tue 02 Jun 2020 06:00 UTC
Issued: Mon 01 Jun 2020 03:56
Forecaster: VAN DER VELDE
A level 2 was issued across southern Russia mainly for large hail, tornadoes and severe wind gusts.
A level 2 was issued across NE Algeria and N Tunisia mainly for large hail and severe wind gusts.
A level 1 was forecast across Georgia and S Russian mainly for large hail.
A level 1 was forecast for C+SW France and NE Iberian Peninsula mainly for large hail.
A large blocking high is over Scandinavia with an easterly flow across Russia, central and western Europe. An active low and upper trough affect Ukraine and S Russia with cool upper air destabilizing effects as far south as Turkey and Greece. Low pressure is found also over SW Europe, where low levels are warm and somewhat humid with steep lapse rates. Similar conditions are over NE Algeria. A small upper cold pool over central France is causing dynamic lift as it moves slowly southward, with enhanced upper winds and deep layer shear. Over N Africa a jetstream of 60 kts overlaps an unstable airmass.
...NE Algeria, Tunisia...
Strong deep layer shear over 20 m/s (0-6 km) and moderate SREH of 200 m2/s2 will help supercell formation in MLCAPE environment of 1000-1500 J/kg. These storms should produce large hail and severe wind gusts.
...NE Spain, SW France...
Moderate DLS of 10-15 m/s 0-6 km and some 500-1000 J/kg MLCAPE can produce potent multicell and some supercell storms which can produce mainly large hail.
...S Russia, Georgia...
Under a southwesterly jet, over 20 m/s 0-6 km shear and 300 m2/s2 SREH form with 500-1000 J/kg MLCAPE. The models indicate convective initiation in the thermal gradient southeast of Ukraine, and appear to simulate an MCS development moving northeastward. Especially the initial storms can produce large hail and perhaps a tornado (0-1 km shear locally over 10 m/s) and an MCS could produce severe wind gusts on a large scale.