Storm Forecast
Valid: Tue 02 Jun 2026 06:00 to Wed 03 Jun 2026 06:00 UTC
Issued: Mon 01 Jun 2026 23:19
Forecaster: PUCIK
A level 1 was issued across N Catalonia mainly for large hail and severe wind gusts.
A level 1 was issued across E France and Switzerland mainly for severe wind gusts, large hail and to the lesser degree heavy rainfall.
A level 1 was issued across NE France, BENELUX and W Germany mainly for heavy rainfall and to the lesser degree marginally large hail and severe wind gusts.
A level 2 was issued for N Italy mainly for large to very large hail, severe wind gusts, heavy rainfall and tornadoes.
A level 2 was issued across SW Slovenia and Istria mainly for heavy rainfall and to the lesser degree for tornadoes.
A level 2 was issued across S Bulgaria and NW Turkey mainly for large to very large hail and severe wind gusts.
A level 1 was issued for S Romania mainly for heavy rainfall and to the lesser degree for tornadoes (SE Romania part).
A level 1 was issued for Finland mainly for heavy rainfall.
DISCUSSION
... N Catalonia ...
One or two fast-moving and intense storms may form over the Pyrenees in the early afternoon hours in very strongly sheared environment and MLCAPE between 500 and 1000 J/kg. Sustained storms will produce swaths of large hail and severe wind gusts.
... N Italy ...
In the morning hours, storms are forecast to be ongoing across the southern flanks of the Alps and perhaps Liguria with an isolated threat of marginally large hail and heavy rainfall. Global models in generally suggest higher coverage of the morning hours compared to the ICON-D2 EPS. Southern extent of the early convection may influence the degree of surface heating and the build up of CAPE. Synoptic-scale lift will overspread the area with an approach of the short-wave trough. Near the surface, an easterly flow will establish across much of the N Italy lowlands with a dry line setting up near the Apennines. Specific humidity of around 12 g/kg combined with modest lapse rates of 6 to 6.5 K/km will yield tall, but rather skinny CAPE profiles across much of the domain. Locally fatter CAPE with values reaching 2000 J/kg are suggested in S Piemonte and near the Apennine dryline. Vertical wind shear will reach 15 to 20 m/s in a deep layer with local amplifications of low-level shear and SRH near the dryline and mesoscale boundary over Piemonte.
Piemonte and the Apennine dryline will become the main foci for the most intense storms of the day. Initiation will start after 12 UTC and ICON D2 EPS suggests high likelihood of supercells over both areas in between of 14 and 18 UTC. Some of the updraft helicity swaths are suggestive of intense supercells forming in locally enhanced SRH near the mesoscale boundaries exceeding 250 m2/s2 in 0-3 km and 100 m2/s2 in 0-1 km layer. Over Piemonte, there's a possibility of storms growing upscale into short linear segment advancing rapidly eastwards. All threats are possible with the strongest storms. Convective mode and surface heating will dictate the most likely threat. Should abundant surface heating occur, higher LCLs and MLCAPE will result in more pronounced very large hail and damaging wind gust risks. Should LCLs stay lower and profiles moister, tornado threat will be augmented. Currently, models suggest moist profiles with very low LCLs, reducing the very large hail/wind gust potential to some degree, while pointing at an increased tornado and heavy rainfall risk. Towards the Alps, repetitive formation of storms may lead to very heavy rainfall threat. Storms will shift east during the day reaching FVG in the late afternoon to evening hours.
... Slovenia, Istria, NW Croatia ...
Towards the late evening and night hours, models simulate saturated profiles with low LCLs, deep warm cloud layer and prevailing southerly flow in low troposphere. Storms will bear predominantly risk of heavy rainfall and ICON-D2 EPS points to the possibility of cell training throughout the night and early morning hours. Should this happen, local precipitation amounts may exceed 200 mm, leading to significant flooding problems.
... E France to Switzerland ...
Skinny CAPE profiles are simulate ahead of a cold front that will impinge on the Alpine chain. Isolated to scattered storms are forecast by the models, forming in an environment of 15 to 25 m/s of 0-6 km bulk shear. Stronger updrafts will be able to become supercells, which is also hinted on by the output of ICON D2 EPS. Given presence of well mixed boundary layer, severe wind gusts seem to be the main threat, although marginally large hail can occur as well. Heavy rainfall may occur in case that some cells repeatedly pass over the same areas in the mountains.
... NE France to BENELUX and W Germany ...
Combination of parallel boundary-relative flow and very moist profiles will yield widespread storms across the area. Expect heavy rainfall to be the main threat initially. Severe wind gust threat will increase towards Germany, where deeper boundary layer is forecast.
... Bulgaria, NW Turkey ...
Scattered to widespread storms will initiate on the local orography and on the stalling weak frontal boundary. Forecast profiles reveal lapse rates increasing towards south with the highest CAPE values on the border of Bulgaria and NW Turkey. Vertical wind shear will increase from morning to late afternoon, eventually reaching 15 to 20 m/s in 0-3 and 0-6 km layers. Expect a combination of well-organised multi and supercells with threats of large hail and severe wind gusts. A risk of very large hail will exist especially over southern Turkey and NW Turkey with fat CAPE profiles.
... S Romania ...
Given moist profiles and slow storm motion, a risk of heavy rainfall will develop across the S Carpathians. Towards SE Romania, a convergence zone is simulated with locally enhanced low-level shear. A conditional tornado risk will be present with storms that latch on this boundary and propagate south along it.
... central Finland ...
Skinny CAPE profiles with very low LCLs and very weak mean wind point to an enhanced risk of heavy rainfall with storms.
