Storm Forecast
Valid: Wed 03 Jul 2024 06:00 to Thu 04 Jul 2024 06:00 UTC
Issued: Tue 02 Jul 2024 22:12
Forecaster: GATZEN

A level 3 was issued across north-western Russia for tornadoes and wind gusts.

A level 2 was issued across north-western Russia for large hail, tornadoes, and wind gusts.

A level 1 was issued across northern Ukraine and north-western Russia for large hail, severe wind gusts, extreme rainfall, and tornadoes.

A level 1 was issued for southern Russia for severe wind gusts.

A level 1 was issued across the Caucasus region for extreme rainfall.

A level 1 was issued across Italy for extreme rainfall.

DISCUSSION

Ahead of low geopotential across central Europe, a frontal boundary extends from the Aegean towards north-western Russia. Around the periphery of the trough, short-wave troughs travel across Italy, western Black Sea, and the Baltic States. A cut-off trough affects the Caucasus area. Upstream, the delta of a strong Atlantic jet stream affects north-western Europe.

North-western Russia

Ahead of an intense, low-amplitude short-wave trough that rapidly lifts into northern Russia, cyclogensis occurs along the frontal boundary that will result in an intense low pressure system at the end of the forecast period. Along and south of the lifting warm front, a moist boundary layer advects into north-western Russia that overlaps with steep lapse rates, and CAPE around 1000 J/kg is expected in response to diurnal heating. Models still differ with the exact location and amount of instability, with GFS indicating mostly elevated CAPE, whereas ICON-EU and ECMWF allow for SBCAPE. Storms will likely develop along the warm front and ahead of the approaching cold front during the day, with ECMWF showing the most activity within the warm sector.

There is impressive vertical wind shear caused by a strong 700 hPa jet streak that points towards the northern nose of the warm air mass (0-3 km shear 25 m/s). Every storm that forms organizes rapidly, with right-moving supercells travelling along the warm front, where long and curved low-level hodographs overlap with low LCLs. ICON shows up to 200 m2/s2 SRH in the lowest 500 m, and tornadoes are expected including strong tornadoes, a violent tornado is not ruled out. Additionally, storm mergers are forecast to result in bow echoes producing long swaths of severe and extemely severe wind gusts.

South of the frontal wave, additional storms travel along the cold front where strong vertical wind shear can also support supercells and training storms with a potential of large hail and severe wind gusts. A tornado and heavy rainfall is also not ruled out.

Southern Russia

Some isolated storms are epxected in a weakly-sheared environment. Inverted-v profiles support isolated severe gusts.

Caucasus

Within the cut-off trough, moist profiles with weak CIN will allow for diurnally driven storms. Slow moving storms will pose a risk of excessive rain or small hail.

Italy

A short-wave trough approaches from the north-west and causes QG forcing. In a weakly sheared environment, sea-breeze convergence will allow for storms in a moist and slightly unstable environment. Slow moving storms are forecast capable of locally excessive rain or hail.