Storm Forecast
Valid: Tue 07 Jul 2020 06:00 to Wed 08 Jul 2020 06:00 UTC
Issued: Mon 06 Jul 2020 22:39
Forecaster: DAFIS

A level 2 was issued for parts of Russia, Belarus, and Ukraine for large hail, severe wind gusts, excessive precipitation and tornadoes.

A level 1 surrounds the level-2 area and Moldova, Romania, Bulgaria, North Macedonia, N Greece, NW Turkey for excessive precipitation, severe wind gusts and large hail.

SYNOPSIS

A deep low-level cyclone over Scandinavia within a trough which is progressively acquiring a negative tilt and the downstream strong poleward advection of unstable air masses will be the main synoptic features during this outlook. The jet stream is cyclonically curved at the south leading edge of the trough with several embedded jet-streaks, but instability is not forecast, except from eastern Europe. The southern flow that has been established due to this synoptic-scale set-up in NE Balkans and Russia is continuously intensifying, bringing warm and moist air masses from the south. Numerous severe DMC events are expected inside the level-2 area.
Moreover, Scandinavia will experience thunderstorm activity, mostly driven by diurnal heating, but also synoptic-scale ascent is expected.


DISCUSSION

.... Russia, Belarus, Ukraine ....

Significant WAA ahead of a PVA in eastern Europe creates a favorable environment for a severe weather outbreak. At the surface, a cold front is currently (22z 06/07) crossing Poland moving east and is expected to intensify as it will meet much warmer and moist air masses ahead of its path in W Russia. A strong low-level flow with veering winds in W Russia will overlap with high CAPE as lapse rates will exceed 7 K/km. All kinds of severe weather are expected within this volatile environment. NWP models do not agree about the exact position of the cold front in the afternoon, where the most intense thunderstorm activity is expected, but also thunderstorms in the warm sector will be able to organize in MCSs and supercells given more than 10-15 m/s DLS and more than 150 m2/s2 0-3km SREH. Large and very large hail is mostly anticipated from isolated supercells, but also MCSs can pose a serious threat by producing straight-line wind gusts, large hail and excessive precipitation. Tornadoes cannot also be ruled out due to the low-level strong flow and helicity, locally exceeding 15 m/s at 850 hPa with 0-1km veering profiles and more than 1500 J/kg SBCAPE. Thunderstorms will continue to propagate NE during the night and in Ukraine and Belarus most of them will become elevated, reducing the severe weather threat.

... rest of the Balkans and NW Turkey ...

The remnants of an old cut-off low are still surrounded by PV maxima and the PBL is very moist with mixing ratios exceeding 12 g/kg. In addition, steep lapse rates will lead to high CAPE with locally more than 2000 J/kg MUCAPE. The main threat will be large hail, but storms may also produce severe wind gusts. Storms should fade late in the evening on Tue 07/07, except N Turkey.