Storm Forecast
Valid: Thu 15 Jun 2023 06:00 to Fri 16 Jun 2023 06:00 UTC
Issued: Wed 14 Jun 2023 23:33
Forecaster: GATZEN

A level 1 was issued across southern Italy, southern Adriatic Sea region, Greece, and southern Balkans for extreme rainfall.

A level 1 was issued across Greece for large hail.

A level 1 was issued across south-eastern France, southern Switzerland, and north-western Italy for large hail.

A level 1 was issued across north-east Poland to Lithuania and western Belarus for large hail.

A level 1 was issued across the Caucasus region for large or very large hail, severe wind gusts, and extreme rain.

A level 1 was issued across south-western Russia for large hail and severe wind gusts.

SYNOPSIS

South of a blocking Scandinavian ridge, a broad mid-level vortex is centered across Czechia. At its southern flank, an intense short-wave trough travels east and will slightly deepen during the period, supporting a far south shifted mid-level jet stream. Downstream, a east moving trough affects parts of Russia and the Near East. Sublte synoptic-scale conditions are forecast across western Europe in the range of a mid-level ridge.

DISCUSSION

Mediterranean

QG forcing affects a convergence zone that slowly moves east during the day. With moist low-levels and modest lapse rates, skinny CAPE profiles with low cloud bases and deep warm cloud area are expected in a weakly-sheared environment. Slow-moving storms are forecast in weak CIN that can produce heavy rain. While a large area is affected by heavy precipitation, contribution due to deep moist convection is limited due to low equilibrium level heights and marginal MUCAPE.

Along the southern portions of the level 1, stronger deep-layer shear and fatter CAPE profiles support an additional large hail threat with isolated storms.

Caucasus area

Together with the progressing trough, steep lapse rates and strong deep-layer shear move out the forecast region during the day. Well-organized storms are possible in the eastern part of the level and will likely be of isolated nature, with supercells possible. Large or very large hail is forecast with these storms. To the west, severe potential decreases with the main hazard being heavy rain due to slow moving storms.

South-western Russia

A warm front wraps arounf the south-east European trough. A hot and well-mixed air mass overlaps with some capped low-level moisture along the front and results in high-based CAPE in a strongly-sheared environment with curved hodographs. Given large CIN, convection is likely limited to the front, with a narrow zone of favourable conditions. Supercells are not ruled out with large hail and severe wind gusts forecast.

Baltic area

Along the northern flank of the central European vortex, a moist easterly flow becomes unstable due to rather steep lapse rates near the trough center and diurnal heating. MLCAPE will be around 500 J/kg overlapping with 10 to 15 m/d deep layer shear. Some large hail can be expected from multicells due to the rather low wet-bulb freezing level.