Valid: Wed 10 Jul 2019 09:00 to Thu 11 Jul 2019 06:00 UTC
Issued: Wed 10 Jul 2019 08:59
A level 3 was issued across Puglia, Italy, mainly for very large hail, damaging wind gusts, tornadoes and excessive rainfall.
A level 2 was issued across Central - South Italy, Albania, Montenegro, North Macedonia, Northern Greece mainly for large to very large hail, damaging wind gusts, tornadoes and excessive rainfall.
A level 1 surrounds Lvl 2 for areas with lower probablities of severe weather.
Satellite imagery reveals a short-wave trough crossing Corsica and Sardegna at the moment, accompanied by isolated thunderstorm activity over these islands. The short-wave is forecast to rapidly translate E-wards, across Italy towards the S Balkans and NW Turkey. As the short-wave crosses the region with very moist airmass and the cold front sweeps across the Adriatic and Balkans towards the Ionian and the Aegean Sea, widespread thunderstorm activity is forecast from Central Italy to N Greece.
Scattered thunderstorms are also forecast over parts of Ukraine, Belarus and Russia, underneath an extensive cyclonic vortex, in the environment of marginal CAPE and weak vertical wind shear.
... Central Italy to N Greece ...
Ahead of the rapidly moving short-wave, mid-tropospheric wind field is forecast to strengthen considerably. Forecast hodographs reveal unseasonably strong bulk vertical wind shear, with 0-6 km values reaching 25 - 35 m/s and 0-3 km values 20 - 30 m/s. While hodographs will stay rather straight, enhanced SRH values are forecast particularly over the coastlines of Puglia with 0-3 km SRH reaching up to 400 m2/s2. Combined with 1000 to 2500 J/kg of MLCAPE in very moist airmass, any developing storm may either become a long-lived intense supercell or a bow-echo, capable of extremely severe weather. Convective mode, isolated cells or a large system, will likely impact the dominant type of severe weather.
As of 9 UTC, a long-lived, right-moving cell is moving along the western Adriatic Sea coastline and several elevated cells are ongoing across S Italy and parts of Balkans. Towards the early afternoon, convective coverage is forecast to rapidly increase over Italy and subsequently also over Balkans, in conjunction with the passage of the short-wave and the front. Storms will spread S and SE during the forecast period and are forecast to reach NW Turkey by Thursday morning.
Storms will be capable of all kinds of severe weather, including tornadoes and excessive precipitation, but the primary threats will be very large hail and damaging wind gusts. A level 3 is introduced for the area where NWP simulates widespread storms in high CAPE, strong shear and high SRH environment as the low level wind field backs to E-ly direction. However, it is possible that the cores of some of the storms will remain over the sea and in such case, severe weather would impact only the offshore areas.