Storm Forecast

Storm Forecast
Valid: Tue 08 Jun 2021 06:00 to Wed 09 Jun 2021 06:00 UTC
Issued: Mon 07 Jun 2021 22:25
Forecaster: DAFIS

A level 1 has been issued for parts of Germany, France and Switzerland mainly for excessive convective precipitation.

A level 1 has been issued for parts of SE France and Italy for large hail, excessive precipitation and tornadoes (waterspouts).

A level 1 has been issued for parts of Romania, Bulgaria, North Macedonia, Greece and Turkey mainly for large hail and excessive precipitation.

A level 1 has been issued for parts of Ukraine, Russia, Belarus and Latvia, for excessive convective precipitation, large hail and severe wind gusts.


No significant atmospheric feature exists over the European domain, as a strong westerly zonal flow has been established above the Mediterranean and a ridge is gradually developing in western Europe. A wide cut-off low swirls over eastern Europe and provides lift to unstable low-level air masses, even though it does not attain high vorticity values. Several more short-wave troughs can be found in the analysis maps, the most important being the one that is about to cross SW France and Italy. In general, many diurnally-driven storms are expected as is indicated on the map, but there is no significant overlap of CAPE and shear, thus, a highly dangerous storm threat is low.


.... Germany, France, and Switzerland ....

No significant lifting mechanism is expected NW from the Alps, but a weak convergence zone and diurnal heating will be able to provide lift to moist air masses. Saturated vertical profiles in forecast soundings indicate that storms will be able to produce excessive precipitation. Apart from the flash flood threat, large amounts of small hail cannot also be ruled out.

.... SE France and Italy ....

South from the Alps, apart from diurnal heating and the moist low-level air masses, one additional ingredient for DMC will be a mid-level high-vorticity blob that will cross western Italy on Tue 09/06. Effective precipitable water is forecast to reach values up to 25-30 mm, so flash floods will be the main threat. Also, despite the weak DLS, MUCAPE may exceed 1000 J/kg, and hail up to 2 cm cannot be ruled out in a few places. During the night, storms will move over the sea where lightning will continue and some waterspouts may form in the Tyrrhenian Sea, posing a threat to the coasts.

.... Romania, Bulgaria, North Macedonia, Greece and Turkey ....

A more complex weather setup is found in this part of the continent. Storms in this region may get benefit of 10-15 m/s to organize in MCSs able to produce large hail and excessive precipitation. NWP models show 24h accumulated precipitation up to 50 mm that can be realized by slow-moving storms, resulting in flash floods.
Rather steeper mid-level lapse rates and stronger DLS will be found over Turkey, where hail may locally exceed 2 cm in diameter.

.... Ukraine, Russia, Belarus and Latvia ....

Under the core of a middle-level cut-of low, numerous storms will develop, mainly driven by diurnal heating. MUCAPE will range from 500 to 2000 J/kg and large hail cannot be ruled out mainly during isolated storms. Storm organization will be difficult in this weakly sheared environment, but slow-moving storms will be able to produce excessive precipitation. Some wet microbursts may be reported, mostly in the northern parts of the level-1 threat area in Russia where LCLs will attain higher values. Finally, a few waterspouts may also form in convergence zones near the coasts of Russia and Ukraine.

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