Storm Forecast
Valid: Tue 22 Jun 2021 06:00 to Wed 23 Jun 2021 06:00 UTC
Issued: Mon 21 Jun 2021 22:52
Forecaster: DAFIS
A level 2 was issued for Switzerland, S Germany, and parts of Austria and the Czech Republic mainly for large hail and severe convective wind gusts.
A level 2 was issued for Estonia and N Latvia for large hail, severe convective wind gusts, excessive precipitation, and tornadoes.
A level 2 was issued for parts of Ukraine and E Moldova mainly for large hail and severe convective wind gusts.
A level 2 was issued for parts of Serbia, Romania, Bulgaria, North Macedonia, and Greece for large hail and severe convective wind gusts.
A level 1 was issued for parts of Ukraine, Moldova, Romania, Serbia, Bulgaria, North Macedonia, and Greece for large hail, severe convective wind gusts, and excessive precipitation.
A level 1 was issued for parts of N Latvia, Estonia, Finland, and Russia for large hail, severe convective wind gusts, excessive precipitation, and tornadoes.
A level 1 was issued for E France, Switzerland, S Germany, parts of Austria, the Czech Republic, and Poland for large hail, excessive precipitation, and severe convective wind gusts.
SYNOPSIS
The trough in western Europe consists of several PV maxima that create favorable conditions for large-scale lift, but the low-level air masses are characterized by rather low theta-e values. Nevertheless, numerous storms are expected in France and Iberia, but they will mostly remain non-severe. A few of them may produce excessive amounts of small hail.
More to the east, over Central Mediterranean, a strong ridge is developing and a WAA takes place toward Italy and the Balkans. Further east, an old cut-off low will keep destabilizing the environment of the Balkans and Asia Minor, as well as the northern parts of the Black Sea.
In northern Europe, the WAA in the Baltic States and E Scandinavia has been completed and very moist air masses will keep moving north under the influence of a high-pressure system in the east (Russia) and a low-pressure system in the west, over Sweden.
DISCUSSION
.... Central Europe ....
Both synoptic lift and diurnal heating will give rise to warm and moist air masses, leading to numerous storms. An overlap of high CAPE and 15-20 m/s DLS suggest that storms will be able to quickly organize and produce large hail and severe wind gusts. SREH will exceed 150-200 m2/s2 only in the eastern parts of the level-2 area, where a few isolated supercells may form. Thunderstorm activity will not totally stop during the night but will become mostly elevated.
.... Balkans ....
Another day with a strong CAPE - DLS overlap in this area. Very steep lapse rates and moist low-level air masses will feed storms after the maximum diurnal heating which will be the main lifting mechanism. A few isolated supercells are expected, starting from the northern parts of the level-2 area that will propagate fast south, producing large to very large hail and severe wind gusts.
.... Ukraine and Moldova ....
NWP models show the development of a shallow cyclone over the Black Sea, bringing very moist air masses onshore, with mixing ratios >15 g/kg. Placed at the northern parts of the cut-off low, there is no significant synoptic lift, so only local convergence zones and diurnal heating will provide lift to these highly unstable air masses. Almost all the available NWP models agree that MLCAPE will exceed 2000 J/kg, overlapping with 10-15 m/s DLS. Both organized and isolated storms are expected, producing severe weather events.
.... Baltic States and Finland ....
A very warm and moist PBL, a convergence zone extending between Latvia and Finland, and very steep mid-level lapse rates will be the main weather features in this part of the continent. NWP models simulate the production of more than 2000 J/Kg MUCAPE, overlapping with 10-15 m/s 0-3km shear and comparable 0-1km shear. Some curved forecast hodographs increase the probability of tornadogenesis in isolated storm cells. Also, large hail and severe wind gusts cannot be ruled out. Many elevated storms will remain active during the night and early morning on Wed 23/06.
