Storm Forecast
Valid: Thu 14 May 2020 06:00 to Fri 15 May 2020 06:00 UTC
Issued: Thu 14 May 2020 06:59
Forecaster: GATZEN

A level 1 was issued across northern Romania, northern Moldova, and southern central Ukraine for severe wind gusts and to a lesser extent large hail.

A level 1 was issued across south-eastern France and north-western Italy for extreme rainfall and large hail.

SYNOPSIS

An arctic trough is located across Scandinavia. Cold and dry air across northern Europe limits the potential for convective storms. Rich moisture can be found along a frontal boundary that extends from southern France to the Alps, northern Balkans and central Ukraine. A frontal wave moves east across the Ukraine today, with a cold front progressing across the country. Over Iberia, an amplified cut-off low is present, yielding a deep south-westerly flow across the Mediterranean.

DISCUSSION

Southern Urkaine and surroundings

Ahead of the approaching cold front, a moist and unstable air mass is advected towards the north-east. Model soundings indicate some weak CAPE overlapping with long, straight hodographs. Within the warm sector ahead of the cold front, scattered storms are expected to initiate during the day. Steep low-level lapse rates and strong vertical wind shear is forecast to support MCS formation, and bowing lines are forecast. Main limiting factor is the weak instability that is mostly below 1000 J/kg. Main severe threat is severe wind gusts, although some large hail is also not ruled out.

Northern Romania

In the wake of the frontal wave across the Ukraine, a quasi-stationary frontal zone affects Romania, and some low-level moisture remains across the Carparthian mountains. Diurnal heating is forecast to result in some weak CAPE today, and storms can form over the mountains. These are forecast to produce isolated severe wind gusts and large hail due to long, straight hodographs.

South-eastern France and north-western Italy

Storms are forecast to form today along the frontal boundary that is associated with moist profiles and modest lapse rates, resulting in weak and skinny CAPE. Warm air advection is forecast ahead of the Iberian cut-off trough and clusters of storms are forecast to produce extreme rain over some locations. The highest potential is expected across north-western Italy.

In the eastern paets of the risk area, strong deep-layer vertical wind shear affects the storms. Although most storms are expected to be too shallow to use this shear, some mesocyclones are forecast, capable of producing large hail.

Balkans

Elevated storms are expected to weaken during the day. Until the end of the forecast period, some more storms are forecast, thanks to an impressive EML adveted across the Mediterranean. Vertical wind shear is very strong and some of these storms can produce large hail. Models do not indicate clear signals for convection initiation. No threat level was issued due to the low forecast confidence.