Storm Forecast
Valid: Thu 26 May 2022 06:00 to Fri 27 May 2022 06:00 UTC
Issued: Wed 25 May 2022 23:36
Forecaster: GATZEN

A level 2 was issued across northeastern Algeria and northwestern Tunisia mainly for large hail and severe wind gusts.

A level 1 was issued across northern and central Italy for large hail and heavy rain.

A level 1 was issued across parts of the western and southern Balkans for large hail and heavy rain.

A level 1 was issued across southern Romania and Bulgaria for large hail and severe wind gusts.

A level 1 was issued across southern Sweden and southern Baltic States for severe wind gusts and tornadoes.

SYNOPSIS

A zonal mid-level flow has established across northern and central Europe, with a short-wave trough moving eastward across southern Scandinavia. At low levels, a frontal boundary is pushed towards the Mediterranean and will be affected by weak QG forcing except for the Balkans, where a weak short-wave trough progresses during the day. A moist and unstable air mass is present farther south. The south-west Mediterranean is affected by a cut-off trough.

DISCUSSION

Northern Algeria and Tunisia

a well-developed vort-max curves around the cut-off trough and provides some large scale lift. Together with diurnal heating, initially high CIN will become weak across the Atlas mountains, and models indicate some storms to develop. With MLCAPE in the order of 1000 J/kg and strong deep layer vertical wind shear of about 25 m/s, supercells are forecast, capable of large or very large hail. Additionally, severe winds are expected due to the well-mixed and deep boundary layer. Storms are forecast to move north-east while the activity can expand northward together with the vort-max. A cluster of elevated storms can be expected late in the period across the south Mediterranean.

Italy and western Balkans

In a moist and unstable air mass, storms are expected along the mountains during the day. Vertical wind shear is limited, and slow-moving storms can cause heavy precipitation along with large hail.

Bulgaria and southern Romania

With some synoptic-scale lift, frontogenesis is forcast along the frontal boundary that spreads south-east. In an unstable air mass, storms are forecast to re-develop along and ahead of the cold front. Strong 0-3 km vertical wind shear points to the potential of bowing elements with the clustering convection, and severe wind gusts are forecast. Additionally, multicells are also capable of some large hail.

Southern Sweden and southern Baltics

A well-developed jet streak moves east on Thursday, and stretching results in steep low-level lapse rates overlapping with some moisture. In a high-shear, low-CAPE environment, some bowing segments and low-topped meesocyclones are forecast, capable of producing severe wind gusts and a few tornadoes.