Storm Forecast
Valid: Wed 29 May 2019 06:00 to Thu 30 May 2019 06:00 UTC
Issued: Tue 28 May 2019 22:15
Forecaster: PUCIK

A level 1 was issued across parts of Balkans, Hungary, western Ukraine and Belarus mainly for excessive rainfall and large hail.

A level 2 was issued across northwestern Russia mainly for severe wind gusts.

A level 1 was issued across northern Turkey mainly for large hail and severe wind gusts.

SYNOPSIS

A deep trough stretching from western Scandinavia towards central Italy is forecast to split during the forecast period with a cut-off developing over Italy and the Adriatic Sea. At the same time a short-wave trough will rapidly eject from Norway towards Finland. The development at mid to upper troposphere will also impact the lower troposphere. A wavy frontal boundary will only slowly move across south-central parts of the Level 1, while a rapidly moving cold front is expected to quickly translate from Scandinavia towards Russia.

DISCUSSION

... Balkans to Belarus ...

Ahead of the cold front, a moderately unstable airmass with skinny CAPE profiles, given the lapse rates of only around 6 K/km, will be present. Scattered to widespread initiation of DMC is forecast along the front and also near the coastlines and orography over the Balkans. From Belarus to Balkans, combination of CAPE ranging from 500 to 1500 J/kg and DLS mostly between 10 and 15 m/s will result in a slight chance of severe convection. Most convective storms will be multicellular in nature, even though a brief supercell is not ruled out, especially over the pre-mountain areas, where shear may be enhanced via mesoscale, orographically driven circulations. Stronger cells may be capable of large hail. Nearly saturated conditions near the cold front will also promote efficient heavy rainfall processes, with attendant threat of flash flooding.

... Northwestern Russia ...

Combination of strong linear forcing, virtually no CIN, weak boundary relative flow and strong shear confined in the bottom 3 km will favour a quick evolution of a quasi linear convective system in this region. Convective system is forecast to evolve before 12 UTC and rapidly move eastwards at around 20 m/s. As bulk vertical wind shear reaches 15 to 20 m/s in the 0-3 km layer, system will likely be well organised and embedded bow-echoes may produce swaths of severe wind gusts. Level 2 was issued due to the expected high coverage of severe weather. Tornadoes may also occur within the line, as well as large hail when the first cells erupt over the region, but these threats will be smaller compared to the wind gusts.

... Northern Turkey ...

Initiation over this area is uncertain given the lack of large-scale forcing and rather dry profiles with potential for updraft dilution. However, sustained storms, forming in the environment of moderate shear, steep lapse rates and high LCLs, will be capable of large hail and severe wind gusts. This warrants a combination of low probability lightning line with a Level 1.