Storm Forecast
Valid: Tue 03 Aug 2021 06:00 to Wed 04 Aug 2021 06:00 UTC
Issued: Mon 02 Aug 2021 21:07
Forecaster: DAFIS

A level 2 was issued for parts of Ukraine and Russia mainly for large or very large hail, severe convective wind gusts and excessive precipitation. Tornadoes are also well possible.

A level 1 area surrounds the Level-2 area and also covers parts of Romania for the same threats with a less coverage extent.

A level 1 was issued for parts of Central Europe mainly for severe convective wind gusts, large hail, and excessive precipitation.

SYNOPSIS

Europe will continue to be divided by extremely hot air masses in the SE and eastern parts and unseasonably cold air masses in the western and central parts. The zonal flow over the Mediterranean results in weak instability, almost all of it strongly capped.

The main synoptic feature during this outlook will be the elongated cold front of a low-pressure system with a center in E Scandinavia. The front extends between Scandinavia and the Black Sea, which will be the main area with DMC events. Another slow-moving low-pressure system will develop over Central Europe as a response to a middle-level shortwave trough. Several storms will develop in Central Europe in a low-CAPE / high-shear environment that creates many questions for CI and the potential severity of the storms.

DISCUSSION

.... Ukraine and Russia ....

While the cold front crosses the eastern parts of Ukraine and West Russia, the influx of very humid low-level air masses from the Black Sea will result in a highly unstable environment. Low-level convergence and upper-level divergence along with the time of maximum diurnal heating, will provide the necessary lift for CI just before noon. Strong DLS in the forecast fields suggests that storms will be able to organize quickly and some of them will become supercells. Large and very large hail will be the main threat by isolated supercells. The convective mode may partially be linear in some sections of the cold front, and severe convective wind gusts will pose a serious threat. Tornadoes are also well possible, even though SREH0-1km does not look impressive. Local patches of high 0-1km shear and low LCLs will increase the probability for some tornadoes in the morning and early afternoon.

... Central Europe ....

A short-wave trough is about to cross Central Europe with a high-vorticity blob. At the surface, rather low mixing ratios suggest that LCLs may be high, above 1000m, but saturated vertical profiles in the NWP models show a potential for flash floods during slow-moving storms. Locally steep lapse rates after the maximum diurnal heating will also increase the threat for large hail, mostly in N Italy, Austria and the Czech Republic. In addition, the belt of a westerly mid-level jet increases the threat for severe convective wind gusts.