Valid: Tue 06 Jul 2021 06:00 to Wed 07 Jul 2021 06:00 UTC
Issued: Mon 05 Jul 2021 21:16
A level 2 was issued for parts of Germany for severe convective wind gusts and tornadoes.
A level 2 was issued for parts of S Germany. E Switzerland and W Austria mainly for large hail and excessive precipitation.
A level 1 was issued for parts of France, Luxembourg, the Netherlands, Switzerland, W Austria, Germany, and Denmark mainly for severe convective wind gusts, tornadoes, and large hail.
A level 1 was issued for W France and S UK mainly for severe convective wind gusts.
A level 1 was issued for parts of Belarus, Ukraine, Moldova and Romania for large hail and excessive convective precipitation.
A strong zonal westerly mid-level flow will progressively become meridional over western/central Europe on Tue 6 July under the influence of a deep trough in the Atlantic and a strong ridge in eastern Europe. At the surface, an unseasonably strong and fast-moving low-pressure system will batter N France, UK and Benelux with severe winds, coming from the Atlantic. The frontal activity of this low will be one of the main convective features of this outlook.
In eastern Europe, an old cut-off low over the Black Sea will destabilize the environment and numerous storms are expected. More to the north, an almost stationary frontal boundary will also feed numerous storms, and some of them may become severe.
.... France, Luxembourg, the Netherlands, Switzerland, W Austria, Germany, and Denmark .....
In the warm sector, ahead of the cold front, a moisture-rich air mass will be the host of numerous storms.
In the northern parts of the large Level-1 and the north Level-2 threat areas, the main threat will be the severe convective wind gusts and tornadoes from isolated storms. Curved low-level forecast hodographs with veering profiles and high shear within an unstable air mass, increase the potential for tornadogenesis. High SREH0-1km values also justify an elevated threat for tornadoes.
More to the south, in SE France, Switzerland, S Germany and W Austria the main threat will be large hail, as steeper lapse rates are found. High mixing ratios and high PWAT also indicate a threat for large amounts of small hail and/or rainfall. The overlap of locally high DLS and CAPE may assist in the organization of storms into an MCS, as suggested by the majority of the available NWP models.
.... Belarus, Ukraine, Moldova and Romania ....
An elongated stationary front that extends from the Baltic States south toward the Black Sea, will be the main lifting mechanism of unstable air masses in eastern Europe. Locally high amounts of CAPE and DLS around 10 m/s increase the threat for hail formation that may reach 2 cm in diameter. In addition, slow storm motions and high PWAT show high potential for storms to produce flash floods. In most areas the storm activity will stop during the night and only elevated storms in the southern parts are expected to continue until the early morning on Wed 07/07.